Genetic studies play a significant role in understanding the underlying risk factors of breast cancer. Polymorphism in the tumor suppressor gene TP 53, CDH1 and ATM genes are found to increase susceptibility for breast cancer globally.This study aimed to identify/analyze the contribution of genetic polymorphisms in the breast cancer candidate genes ATM, TP53 and CDH1 that may be associated with familial breast cancer risk in the Khyber Pakhtunkhwa population.In the present case-control study, Whole Exome Sequencing (WES) of the 100 breast cancer patients and 100 ethnic controls were performed for the selected genes in the target population.Of the studied variants rs3743674 of the CDH1 gene (crude P=0.014 and adjusted p=0.000) evident significant association with breast cancer in Pakistani Pashtun population. Whereas TP53rs1042522 (crude P=0.251 and adjusted P=0.851) and ATM rs659243 (crude p=0.256 and adjusted p=0.975) showed no or negative association with breast cancer in study population.The present study demonstrates that CDH1rs3743674 polymorphism is associated with elevated breast cancer risk in the Pashtun ethic population of Khyber Pakhtunkhwa. Breast Cancer (BC) is the most frequent type of all cancers reported worldwide. In males it accounts for less than 1% of the total cases reported Maximum cases arise infrequently in individuals with slight or no family antiquity of the disease Emerging evidences suggest that BC can arise due to changes in human cadherin-1 (E-cadherin/ CDH1) gene and tumor suppressor gene (TP53) CDH1 rs3743674, ATM rs659243 and TP53 rs1042522 polymorphisms of breast cancer risk in females of Khyber Pakhtoon Khawa, Pakistan. A large number of studies have been conducted on breast cancer patients globally, but no study on the subject has still been performed in this population. So we suppose to get a good perceptive of risk linked with such polymorphisms in the females of KP, Pakistan.In this study, the correlation was determined between th October, 2018.A Case-Control study was designed consisting of 100 Familial Breast Cancer patients and 100 gender- and age-matched healthy volunteers, recruited from various Tertiary care hospitals including Institute of Radiotherapy & Nuclear Medicine (IRNUM) hospital, Peshawar, Khyber Teaching Hospital (KTH), Peshawar, and Hayatabad Medical Complex (HMC), Peshawar. Patients were histopathlologically confirmed with breast cancer. Case as well as control samples of whole blood were collected after through physical examination, informed written consent from patients or guardians authorizing the use of blood samples and their clinical data, in a properly labeled EDTA tubes. A detailed and carefully designed patient history proforma having information regarding breastfeeding duration, menarche and the menstrual cycle, use of oral contraceptives, age and demographic characteristics with lifestyle factor data were noted from the medical reports accompanied by a personal interviewer-administered questionnaire that was conducted by nurses in the presence of physicians Inclusion and exclusion criteria of the patients and healthy individuals were as follow: (i) patients who have histopathologically confirmed BC with at least one first and/or second-degree relatives and (ii) aged between 25 to 65 years were included, while (i) patients who have no family history of BC or (ii) aged below 25 and above 65 years were excluded from the study.Criteria for control subject's selection: (i) Normal healthy age-matched subjects of similar ethnicity and (ii) aged between 25 & 65 years and free from breast cancer.The genomic study was conducted at the Genomic Center of Rehman Medical Institute, Hayatabad Peshawar, Pakistan, using Next Generation Sequencing (NGS).DNA was extracted using standard DNA extraction Kit , as per manufacturer's instructions. Quality of DNA was confirmed by running on 1% agarose gel and the quantity was checked by Qubit® fluorometer with the aid of dsDNA high sensitivity kit . After quantification of DNA, each sample was properly labeled, recorded according to the DNA concentration present and stored at –20°C for further analysis Prior to Library Preparation, quantification of DNA was done using Qubit Fluorometer with the help of dsDNA high sensitivity kit  and the concentration was adjusted to 10 ng/µL.DNA fractions extracted from of all samples (included in the study) were pooled according to the previously described protocols Illumina Nextera XT DNA library kit (Cat. No. FC-142-1123) was used to generate paired-end libraries (2101 bp) by properly following the manufacturer guidelines Paramagnetic beads were used to eliminate fragments of less than 150–200 bp (unamplified) after the PCR amplification was completed. The exome amplified pieces of DNA (pre-selected genomic regions of interest) were then maintained, while non-specified DNA fragments were removed using biotinylated probes, as per the capture method plan. Using an Agilent 2100 Bioanalyzer (Agilent 228 Technologies), libraries were measured to confirm final DNA concentration.Finally, the sequencing of the generated libraries was completed using the Illumina MiSeq NGS Machine. The sequence data generated by the Illumina MiSeq NGS Machine was saved in FASTQ format.The study was conducted in the Center for Genomics, Rehman Medical Institute Hayatabad, Peshawar Pakistan.The FAST Q files obtained were subjected to different downstream analysis. These files were filtered on the basis of quality score using ‘Trimmomatic’ software to eliminate the Q30 & Q20 files and analyze Q40 & Q30 files only. For the data analysis and alignment, the newly identified sequence reads were aligned to a reference genome with the help of bioinformatics Burrows-Wheeler Aligner (BWA) software and BAM files were visualized on Integrated Genome Viewer (IGV). After alignment, differences between the reference genome, variant calling (vcf), and the newly sequenced DNA reads, were identified and analyzed.A chi-square test (χ2) was performed to know the relationship of genotypes of patients and healthy controls with breast cancer risk. Assessment of odd ratio (OR) and 95 % confidence intervals (CIs) was estimated through binary logistic regression. The P<0.05 was considered statistically significant. ORs were also calculated for various clinicopathological characteristics for both the mutation carriers and non-carriers. All of the statistical analysis was determined by applying the SPSS software, version 21.00.Demographic as well as other characteristics such as use of oral contraceptives, duration of breast feeding, area of residence, education and history of breast cancer in the first and/or second degree relatives, were studied as given in the Age groups and marital status showed no significant deviation (P>0.05) between patients and controls, whereas significant deviation (P>0.05) was found between users and non-user of drugs/contraceptives (P=0.003) and as well as in socioeconomic status groups.According to different age group, majority of the patients 37 (21%) belongs to age group 46–60 years followed by 31(17.6%) [31–45years], 14(8%) [15–30years] .All of the subjects were females and no male patient throughout the study was observed. Regarding regional distribution of the patients shown in Different clinicopathological parameters like menarche, age at clinical stages , no. of children, duration of breast feeding, enlargement of breast and ulceration, mobility, tenderness of breast, nipple discharge, Peaudorange, cyclical pains, Lymphedema, weight loss and liver changes were also studied . SignifiWhole Exome Sequencing (WES) results are shown in TP53rs1042522, CDH1rs3743674 and ATM rs659243 polymorphism of both controls and cases are given in CDH1rs3743674 polymorphism (crude P=0.014 and adjusted P =0.000) was evident as risk variant and increases risk for breast cancer in the Pashtun ethnic population of Pakistan. TP53rs1042522 and ATM rs659243 polymorphism showed No/negative association with breast cancer in the present studied population.The allelic and genotypic frequencies of TP 53 and cell-cell adhesion CDH1 genes is found to increase susceptibility for breast cancer TP53rs1042522, CDH1rs3743674 and ATM rs659243) were screened for its association with BC in Pashtun ethnic population. Association of TP53 rs1042522 with breast cancer was reported CDH1 and TP 53 and ATM genes mutations in patients, by comparison, to ethnically matched controls.Genetic modification due to single nucleotide polymorphism in the genomic DNA has an involvement in cancer development TP53 emerges as an essential regulatory protein that acts as a multifunctional transcription factor to control the cell-cycle progression, restore DNA damage to keep the integrity of genome and induces apoptosis where stressors create abnormal and irreversible injury to eliminate the smashed cells In the current study, we found an alliance among the rs3743674 mutant and breast tumor (crude P= 0.014 and adjusted P=0.000). A high risk of breast cancer for Pro/Pro homozygosity  was also found in AustrianAll these results are in line with our findings. Moreover our findings are not in line with those studies which establish a high frequency of homozygosity of Arg in breast cancer patients as reported in Turkish Reports have shown that TP 53 Arg 72 variant is more efficient in the initiation of apoptosis E-cadherin has an important role in cellular differentiation, inter-cellular adhesion and cell signaling. Studies have shown the association of different types of cancers with CDH1 rs3743674 polymorphism, however some other reports have shown no significant relation. The non-significant relation may be due to genetic and ethnic variability of the patients and controls that might be responsible for this inequality among these information. Our findings are in line with the majority of the studies conducted in different populations. The genetic changes in CDH1 gene along with cellular polarity and cell-to-cell adhesion, is finally accountable for the metastasis and tumor progression CDH1rs3743674 and TP53rs1042522 polymorphisms with the risk and breast cancer progression CDH1 rs3743674 and ATM rs659243 genes in breast cancer for the first time in patients of Khyber Pakhtunkhwa population to evident the association of the aforementioned gene varints with BC in study population.A previous study relates Our results show a significant association of CDH1 rs3743674 polymorphism with increasing risk of breast cancer in the Pashtun population of Pakistan. This study will help to provide a plate form for future diagnosis and treatment of breast cancer patients. Similar projects should be designed by national governmental agencies to screen and pinpoint genetically susceptible individuals and awareness campaigns are needed regarding genetic susceptibility and environmental risk factors be initiated in general public.


Evidence on a possible association between newer hormonal contraceptives (HC) and risk of breast cancer remains inconclusive, especially as concerns progestogen-only methods.st 2005, or who turned 15 years during the study period, were followed until December 31st 2017. Using information from seven National Registers, we assessed the risk ratio of developing breast cancer and breast cancer in situ in relation to different HC using Poisson regression. We adjusted the analyses for several known confounders of breast cancer.In this nationwide prospective cohort study, all Swedish women aged 15–34 at study start on January 1This cohort included 1.5 million women providing more than 14 million person-years. During the study period, 3842 women were diagnosed with breast cancer. Compared with never users of any HC, we found no increased risk of developing breast cancer among current users of any combined HC, IRR 1.03 (0.91–1.16), whereas current users of progestogen-only methods had an increased risk of developing breast cancer, IRR 1.32 (1.20–1.45). Across all types of HC, the risk of developing breast cancer appeared to be highest the first five years of use (combined HC IRR 1.39 (1.14–1.69); progestogen-only methods IRR 1.74 (1.44–2.10). The risk disappeared ten years after the women stopped using HC. The absolute risk of breast cancer per 100,000 women-years was 22.4 for never users, 10.9 for current users of combined HC, and 29.8 for current users of progestogen-only methods.Current use of progestogen-only methods is associated with a small increased risk of developing breast cancer, whereas we could only detect an increased risk among users of combined HC during the first five years of use. This may partly be explained by a selective prescription of progestogen-only methods to women with risk factors for breast cancer, like smoking or obesity. As the absolute risk of breast cancer was small, the many health benefits associated with HC must also be taken into account in contraceptive counselling.This study was funded by the Swedish Cancer Society and by the Uppsala County Council, the Faculty of Medicine at Uppsala University. On October 6, 2021 we searched PubMed for articles published between 1985 and 2021 without any language restrictions using the search terms (“breast cancer”) AND .Current use of HC has been associated with a small increased relative risk of breast cancer in several studies. This risk appears to disappear gradually within five to ten years after cessation. However, evidence on progestogen-only methods is lacking, and many studies include methods that are no longer used. New methods have arrived on the market, including lower-dose combined oral contraceptives and efficacious progestogen-only preparations.st 2005, or who turned 15 years during the study period, were followed until December 31st 2017, providing data on more than 14 million person-years. Combined with a high user-rate of progestogen-only contraception, this population-based study provides excellent generalisability and allows investigation of different subtypes of HC.In this nationwide prospective cohort study, all Swedish women aged 15–34 at study start on January 1Compared with never users, we found no overall increased risk of developing breast cancer among current users of any combined HC, IRR 1.03 (0.91–1.16), whereas current users of progestogen-only methods had an increased risk of developing breast cancer, IRR 1.32 (1.20–1.45). Across all types of HC, the risk of developing breast cancer appeared to be highest the first five years of use (combined HC IRR 1.39 (1.14–1.69); progestogen-only methods IRR 1.74 (1.44–2.10)) and to disappear ten years after the women stopped using HC.Our data support an association between the use of progestogen-only methods and breast cancer development, but we only found a modest association for combined HC during the first five years of use. This may be explained by a more liberal prescription of progestogen-only methods to women with risk factors for breast cancer, such as smoking and obesity. Small risk estimates close to one are also likely to contribute to the inconsistent evidence on HC and breast cancer risk, and it remains unclear if the associations observed are casual.As the risk of breast cancer is greatest among current users of HC whose prevalence of the disease is very low, the absolute risk of breast cancer among users of HC is minimal. However, given the extensive use of HC globally, more research is needed especially on progestogen-only methods, to optimize contraceptive guidelines and enable tailored contraceptive counselling to individual patients.Alt-text: Unlabelled boxHundreds of million women use hormonal contraception (HC) globally, and to many of these, the risk of developing breast cancer is a concern. The role of HC in breast cancer development has been debated for decades. Many studies have shown a small increased relative risk of breast cancer among current and recent users of combined oral contraception that disappears progressively within five to ten years after HC use is stopped.,,,,,,,,,Most prior studies are case-control studies, assessing the lifetime exposure to combined HC instead of current use, which is more relevant to women considering HC. In addition, many of the older studies are based on pills with higher ethinyl estradiol doses (≥50 mcg),,,,,,,In recent years, stemming from evidence on menopausal hormone therapy, an increased risk of breast cancer associated with methods containing progestogen has been detected.Our aim was to study the risk of developing breast cancer among current users of HC, with a particular focus on progestogen-only methods.The regional ethical review board in Uppsala approved the study, DNR 2017/546.st 2005, or who turned 15 years during the study period, were followed until December 31st 2017. The oldest women in the cohort were followed up to the age of 45. As the Swedish Prescribed Drug Register  started relatively recently, we only included women up to age 34 to avoid misclassification of older women as never-users. All Swedish residents have a unique identification number, which enables linking of information across several registers. We retrieved information from seven national registers: (1) The SPDR, (2) The National Patient Register with information on diagnoses classified according to the International Classification of Diseases and Related Health Problems version 10 (ICD-10), (3) The Swedish Medical Birth Register with information on virtually all deliveries and pregnancies from gestational week 22, (4) The Cause of Death Register with information on all dates and causes of all registered deaths, (5) The Total Population Register covering information on all Swedish residents registered as living in Sweden at any point since 1961, (6) The Multi-Generation Register containing information on individuals’ relation to biological or adoptive parents, and finally, (7) the Education Register.All Swedish women aged 15–34 at the study start on January 1Women were excluded if their mother had died from breast cancer or if they themselves had been diagnosed with breast cancer , gynaecological cancer (ICD-10 codes C51–C58), venous thromboembolism (VTE), stroke or cardiovascular disease , or if they had emigrated. During the study, women were permanently censored if they died, emigrated or developed contraindications for combined HC use like gynaecological cancer, venous thromboembolism, coagulation defect, stroke, cardiovascular disease, systemic lupus erythematosus (ICD-10 code M32), or migraine with aura (ICD-10 code G43.1), whichever occurred first. Women were temporarily censored 12 months before giving birth and 6 months postpartum. Finally, we excluded the person-years for women aged 45 years or more as there were too few in this age group to make any viable analysis.2 and smoking among women ≥35 years). Women with risk factors are either prescribed progestogen-only methods or are referred to a physician.Information on redeemed prescriptions of HC between July 1st 2005 and December 31st 2017 was retrieved from the SPDR. The Anatomical Therapeutic Chemical (ATC) classification codes enabled drug identification. The SPDR covers all HC used by women in Sweden, as HC can only be prescribed by nurse-midwives or physicians. Prescription of HC for healthy women in Sweden is almost exclusively performed by nurse-midwives, and is free-of-charge up to age 20 or 25, depending on geographic area. Nurse-midwives must comply with the National Guidelines, which in turn are based on the Medical eligibility criteria for contraceptive use by the World Health Organization.The defined daily dose (DDD) was used to estimate exposure time. Contraceptive patches and vaginal rings can be prescribed for three, six or twelve months. As the DDD is lacking in the SPDR for these methods, we assumed they were used for six months. Further, we assumed that the levonorgestrel-releasing intrauterine system (LNG-IUS) was used for four years, unless the woman was censored for pregnancy or because she started another HC method before the 4-year time period had ended. The LNG-IUS was analysed separately from the other progestogen-only methods.Women were categorised as current users when they redeemed a prescription of HC during the study period. The current exposure time of dispensed prescriptions, except the LNG-IUS, were extended with 180 days as biological transformations may not be apparent until some months after starting use. Thus, the category ‘current users’ also include recent users. Women were categorised as previous users when the extension phase (i.e. DDD + 180 days) ended. We also performed additional analyses where ‘current users’ included DDD + 365 days to ensure sufficient time for biological transformation and detection of HC-induced cancers. Women who had not yet or who never redeemed a prescription of any HC during the study period were categorised as ‘never users’.In the rare case where a woman retrieved two different oral HC the same day, both methods were censored until a new prescription was retrieved. If she retrieved an implant or LNG-IUS together with any type of oral contraception on the same day, she was presumed to have used the implant or the LNG-IUS. HC were categorised as shown in in situ or invasive) or death from breast cancer. These were defined as either the ICD-10 codes D05  or C50, retrieved from the Patient Register, or the ICD-10 code C50 from the Swedish Cause of Death Register. Additional analyses were performed with invasive breast cancer-only as outcome.The outcomes were any type of breast cancer . Women with no information in the Swedish Medical Birth Register were assumed to be nulliparous. Information on smoking was collected when registering for antenatal care for the first pregnancy, and information on BMI was collected from the most recent pregnancy. Finally, the National Patient Register provided information on any infertility diagnosis (ICD-10 N97), polycystic ovarian syndrome (ICD-10 E282 and L680) and endometriosis (ICD-10 N80), and the SPDR provided information on ovulation stimulating treatment (ATC G03G).in situ as event. Age was used as a time-varying variable, with 5-year age bands. The reference group was women who had never used HC. The individual woman could contribute both as never, current and previous user of HC. A two-sided p-value of less than 0.05 was considered significant in all analyses and IRR are presented with 95% confidence intervals (CI).We calculated the crude and adjusted incidence rate ratios (IRR) of breast cancer among different user groups of HC using Poisson regression models with incidence of breast cancer or breast cancer We performed the adjustments for covariates in two models. In Model 1, we adjusted for age, level of education , place of birth , age at first birth , number of children  and any diagnosis that suggested HC was used for medical purposes  or ovulation stimulating treatment. In Model 2, we added information on BMI and smoking; these data were assessed as complete-cases in the analyses and included parous women only. All variables were treated as categorical except BMI and age that were entered as continuous variables.We investigated the effect of duration of use and time since last use by presenting the age-adjusted IRR using Poisson regression. We studied the (1) duration of current episode of use (2) the cumulative duration of use, and (3) time since last use, all compared with all never users. Women were grouped into use of <5 years, 5<10 years and ≥10 years. Women were allowed to contribute in all three groups.All analyses were performed using R Statistics version 4.1.0 except the descriptive statistics that were performed in IBM SPSS version 28.0. All IRR in the results section are adjusted according to Model 1 if not otherwise specified.The funding sources were not involved in the conduct of the study.in situ and 3346 were breast cancers. Of the 495 cases with breast cancer in situ, 261 later developed breast cancer. One death from breast cancer, not previously diagnosed, was recorded. This generated a breast cancer incidence of 26.8 per 100,000 women-years in this population. Overall, 3.2% of the breast cancers occurred among women aged 15–25, 27.3% among women aged 25–35 and 69.5% among women aged ≥35 years, This cohort included 1,652,364 women followed from 2005 to 2017 with a mean follow-up time of 8.7±3.9 years and a total of 14,330,806 person-years. During this time period, 3842 events of breast cancer were recorded, of which 495 cases were breast cancers Women were between 15.0 to 45.0 years of age and the mean age was 25.7±7.4 years. The distribution of person-years in the age groups < 20, 20–29.9, 30–39.9 and > 40 were 23.4 %, 43.9 % 27.5 % and 5.2%, respectively. Almost half of all women had used combined HC (47.8%) and these women were generally younger, had a lower BMI, and were more often nulliparous compared with the remaining women. Around 36.6% of all women had used progestogen-only methods. These women were more often parous, had a higher BMI, and were more often smokers compared with the remaining women. The study population is described in in situ (IRR 1.03 (0.91–1.16) (Current users of any combined HC method had no increased risk of developing breast cancer or breast cancer 91–1.16) , model 191–1.16) . AnalyseHowever, a modest risk of breast cancer with combined HC was noted the first five years of use (IRR 1.39 (1.14–1.69)), which disappeared after five years of use . The risin situ in comparison with never users of any HC, IRR 1.32 (1.20–1.45) (Current users of progestogen-only methods had an increased risk of developing breast cancer or breast cancer 20–1.45) , model 120–1.45) , model 2Analyses in women with invasive breast cancer only, and analyses where we increased the time-lag for current use to 12 months yielded similar findings (Supplementary Tables 1 and 2).The risk of breast cancer with progestogen-only methods was highest the first ten years of use  and 5–10 years; IRR 1.26 (1.06–1.49)) and diminished after ten years of use . This inTo rule out the possibility that the elevated risk of developing breast cancer among users of progestogen-only contraception was due to recent prior use of combined HC, we compared women who had exclusively used progestogen-only methods with never users. The risk of developing breast cancer in exclusive progestogen-only contraceptive users remained elevated in this analysis, IRR 1.29 (1.07–1.56).We also evaluated risk of breast cancer in foreign-born women, nulliparous women and women under the age of 20. Due to few cases, we performed the analyses with any hormonal contraception as exposure. We found an increased risk among women under the age of 20 years, IRR 4.03 (1.33–12.21), but the absolute risk in these women was only 0.8/1,00,000 person-years (Supplementary Table 3).in situ compared with women who have never used HC. We could not detect any overall increased risk among users of combined HC, except a slightly increased risk during the first five years of use. The risk of breast cancer appeared to be highest during the first ten years of progestogen-only methods use. Across all HC, the risk of developing breast cancer disappeared within ten years after stopped use. Although we demonstrate an increased relative risk of developing breast cancer, the absolute risk of acquiring breast cancer from combined HC or progestogen-only method use was small in this population of women 15–34 years of age at study start.Swedish women who use progestogen-only methods have a marginally increased relative risk of developing breast cancer or breast cancer We could not identify any overall increased risk of developing breast cancer among current users of combined HC or in any of the different combined HC formulations. This contrasts to the findings by the Collaborative Group,We identified an increased risk of developing breast cancer among current users of progestogen-only methods as well as among exclusive users of progestogen-only methods. The increased risk was consistent across all formulations for which we had adequate statistical power. We could not detect any major differences between the different formulations, except for the depot medroxyprogesterone acetate (DMPA) injectable.As progestogen-only methods have previously not been widely used globally, there are only a few studies to compare with. In the Norwegian Women and Cancer (NOWAC) Cohort Study, users of progestogen-only methods had similar relative risk of developing breast cancer as found in our study.,,Current users of DMPA had a decreased risk of developing breast cancer compared with never users of HC. Evidence from former studies also points towards no increased risk for breast cancer in this group, although findings are not entirely convincing.,Current use of the LNG-IUS was associated with a small increased risk of developing breast cancer compared with never users. This association was also prevalent in a Danish study as well as in a meta-analysis, in which the odds ratio was 1.12 for premenopausal women.On the one hand it is not surprising that progestogen-only methods increase the risk of developing breast cancer, as women using oral progestogen and implants maintain their endogenous production of oestrogen  and as progestogen stimulate cell proliferation. On the other hand, users of progestogen-only methods in our cohort constitute a selected group, as discussed above. The latter is further noted when we adjust for BMI and smoking, by which risk estimates for breast cancer became somewhat attenuated. As BMI was only available in 37% of the study population, we cannot rule out that this finding is affected by residual confounding, including not only BMI, but also health literacy, physical activity, dietary patterns, alcohol consumption, age at menarche, and breastfeeding.The effect by which hormonal contraceptives are thought to influence breast cancer risk could be due to direct stimulatory action on breast tissue, for instance, via cross regulatory signalling networks between the estrogen receptor (ER) α and BRCA1,,,,We found a marginally increased risk of developing breast cancer in the first five years of combined HC use, and during the first ten years of POP use, which in both contraceptive groups diminished with longer duration of use. Studies on a time- and dose-dependent effect of combined HC on breast cancer development have given inconsistent results; some have found a moderate effect that appears at various time points,,,,,,In line with former studies,This large, nationwide prospective cohort study included almost 1.7 million women who were followed for thirteen years, which provided us data on more than fourteen million person-years. More than 2.6 million person-years on progestogen-only methods were included, which is more than in any prior study. The use of national registers is a strength as they cover all Swedish women, all cases of diagnosed breast cancer and all redeemed prescriptions of HC in Sweden. In comparison to our study, most former evidence on the association between HC and breast cancer comes from case-control studies, which are susceptible to recall bias and have limited generalisability.We included reliable information from the national registers on several potential confounders, including variables that are strongly associated with breast cancer risk.in situ versus invasive cases (12.8% vs 12.8%).The incidence of breast cancer was assessed using The National Patient Register. This register only covers diagnoses reported by a clinician and not from the pathology laboratory. The major advantage of the Cancer Register is the quality check with the pathology register, which means it only includes incident cases. With our young study population, however, most breast cancer are bound to be incident, i.e. we find it unlikely that the diagnoses merely reflect history of breast cancer. Comparing our data with data from the National Cancer Register with 99% coverage of breast cancer diagnoses,in situ compared with women who have never used hormonal contraceptives. In contrast, we could not detect any overall increased risk among current users of combined HC. However, the risk with combined HC and progestogen-only methods appears to be greatest during the first five and ten years of use, respectively. Across all HC, the risk of breast cancer persisted up to ten years after stopped use. As the risk of breast cancer is greatest among current users of HC whose prevalence of the disease is very low, the absolute risk of breast cancer among users of HC is minimal. However, given the extensive use of HC globally, more research is needed especially on progestogen-only methods, to optimize contraceptive guidelines and enable tailored contraceptive counselling to individual patients. At the same time, the many health benefits associated with HC must also be taken into account in contraceptive counselling.Swedish women in our cohort of women, 15–34 years of age, who currently use progestogen-only methods have a small increased relative risk of developing breast cancer or breast cancer Jenny Niemeyer Hultstrand was involved in the following study activities: conceptualisation, data curation, formal analysis, investigation, interpretation of results, methodology, project administration, software, validation, interpretation, visualization, writing manuscript.Kristina Gemzell-Danielsson was involved in the following study activities: conceptualisation, validation, interpretation of results and writing (review and editing).Helena Kopp Kallner was involved in the following study activities: conceptualisation, validation, interpretation of results and writing (review and editing).Henrik Lindman was involved in the following study activities: conceptualisation, validation, interpretation of results and writing (review and editing).Per Wikman was involved in the following study activities: data curation, formal analysis, investigation, software, validation and visualization.Inger Sundström Poromaa was involved in the following study activities: conceptualisation, data curation, formal analysis, funding acquisition, investigation, methodology, project administration, resources, supervision, validation, interpretation of results and writing (review and editing).No individual participant data can be made available or shared. Study protocol and data dictionaries are available upon contact with the corresponding author.Jenny Niemeyer Hultstrand has received funding from the Family Planning Fund, Uppsala University, and travel grants from the Swedish Society of Medicine.Kristina Gemzell-Danielsson has acted as consultant for Bayer, Gedeon Richter, Exeltis, Natural Cycles, Daisy, Medincell, Cirqle, ObsEva, Mithra, Vifor. She has received lecture fees from Bayer, Gedeon Richter, Exeltis, Nordic Pharma, Natural Cycles, Mithra, and Organon.Helena Kopp Kallner has received lecture fees from: Actavis, Bayer, Gedeon Richter Exeltis, Nordic Pharma, Natural Cycles, Mithra, Teva, Merck, Ferring, Consilient Health, and acted as consultant for Bayer, Evolan, Gedeon Richter, Exeltis, Merck, Teva, TV4, Natural Cycles, Pharmiva, Dynamic Code, Ellen, Estercare, Leia and Essity.Henrik Lindman has received lecture fees from Lilly, AstraZeneca, Novartis, and Daiichi Sankyo.Per Wikman reports no conflicts of interest.Inger Sundström Poromaa has served occasionally on advisory boards or acted as invited speaker at scientific meetings for Bayer Health Care, Gedeon Richter, Peptonics, Shire/Takeda, and Sandoz. ISP is supported by grants from the Swedish Research Council 2020-01801 and the Swedish Cancer Society.


This study aimed to investigate breast cancer screening practices and associated factors among Chinese‐Australian women. A cross‐sectional quantitative survey method including convenience and snowball sampling was used to recruit 115 Chinese‐Australian women living in Sydney, using a self‐administered survey. In all, 69.8% of participants reported recent clinical breast examinations and 73.3% had mammograms. Age, religion, employment status, and length of residence were associated with having a clinical breast examination. Income was related to having a mammogram. Associations between knowledge of breast cancer, cancer‐related beliefs, and screening participation were found. Length of residence in Australia was the strongest predictor of having a clinical breast examination and mammogram. The most common barrier to mammography was if women felt that doctors did not recommend it to them. Chinese‐Australian women need to be educated about awareness of their usual breast health to be aware of any changes, especially if women are not eligible for mammography or have difficulty in accessing health services. Tailored programs, improving screening experiences, and minimizing perceived barriers are needed to promote early detection of breast cancer among Chinese–Australian women. Early detection of breast cancer through screening is an important strategy to improve breast cancer outcomes.Little is known about the current breast cancer screening practices of Chinese‐Australian women who are at increased risk of breast cancer upon migration to Australia.Chinese‐Australian women are under‐represented in breast cancer screening and there are barriers to participation in screening.1In Australia, early detection plays a leading role in reducing mortality from breast cancer; however, little is known about how Chinese‐Australian women engage in breast cancer screening. Breast cancer is the most common invasive cancer and the second leading cause of death from cancer among women in Australia  investigate the practices of Chinese‐Australian women living in Sydney in relation to the main breast cancer screening tests (CBE and mammography); and (ii) identify any factors associated with their breast cancer screening behaviors.2This cross‐sectional quantitative study used self‐administered surveys for data collection from July to November 2016. The study was approved by the University of Sydney Human Research Ethics Committee . There was a potential for the survey questions to be sensitive, so participants were approached in person and the first author also provided an oral explanation in Mandarin  before participants completed the survey. During the initial contact, potential participants were given a Participant Information Statement (PIS), a consent form, and a copy of the study survey in English or Simplified Chinese (written Chinese). All participants were asked to sign the consent form before completing the survey. Participants were able to choose to return the signed consent form and the study survey immediately or to send them to the chief investigator's office using stamped addressed envelopes.The target population for the study were Chinese‐Australian women living in Sydney. For this study, the term Chinese‐Australian women refers to any Chinese woman who migrated to Australia from mainland China or Hong Kong. The eligibility criteria included Chinese‐Australian women who were (i) aged 35 years and over, as breast cancer prevalence starts to increase at this age . Section n = 113), 0.78 for the breast cancer treatment scale , and 0.72 for the breast cancer detection scale .Participants' knowledge of breast cancer was assessed on symptoms of breast cancer (8 items), treatment options for breast cancer (5 items), and detection of breast cancer (5 items). Responses to all items were “yes” or “no.” To assess the degree of knowledge regarding breast cancer, knowledge scales were constructed in SPSS 22.0 on the basis of two items: knowledge of breast cancer symptoms and knowledge of breast cancer treatment options. For symptom knowledge, participants were asked to tick symptoms they knew of which consisted of seven possible responses. If the participant ticked an item indicating that they knew it was a symptom of breast cancer it was coded “1,” and not knowing it was coded “0.” The knowledge scale gave the mean for each group with 0 (not knowing any symptoms) being the lowest possible score and 7  being the highest possible. For treatment options there were five possible answers, therefore 5 was the highest possible score that could be obtained . Each question also included a “not sure” option, which was excluded from the knowledge scale. Reliability statistics were calculated for each scale. The Cronbach's alpha coefficient was 0.78 for the breast cancer symptom scale  version 22.0. All data provided by the participants were entered, regardless of any missing items that were not answered. Descriptive statistics were used to summarize the demographic characteristics and breast cancer screening practices of the participants. Normality was assessed by visual inspection of histograms. The income survey items were recoded into two groups (“$20 000 to $50 000” and “>$50 000”). This was based on the known median family income of new migrants ($27 406) and long‐ term migrants ($53 999)  and dependent variables . Associated variables from this analysis were entered into a binary logistic regression to assess the impact of the predictors on the likelihood of participating in breast cancer screening tests.Educational level items were recoded to “Secondary school or less” and “Tertiary”; length of stay in Australia was re‐coded to “<10 years,” “10 to 20 years,” and “>20 years.” All significance levels were set at t‐tests also were used to explore the relationship between the knowledge scales of breast cancer and breast cancer screening practices. The Mann–Whitney U‐test and independent sample t‐tests were used to analyze the association between cancer‐related beliefs and breast screening participation. Multivariate analysis (the binary logistic regression) was undertaken to predict the dependent variables. Lastly, descriptive statistics were used to summarize the barriers of participating in CBE and mammograms.Chi‐square tests were conducted to examine the relationship between categorical variables (demographic and acculturation variables) and screening practices. Independent sample 3A total of 115 eligible Chinese‐Australian women completed and returned a survey. The characteristics of the participants are shown in Table n = 3 a; sister, n = 2; and aunt, n = 1). One participant reported a death in the family due to breast cancer. In terms of self‐rated health, 17.8% rated their health as excellent, 29.9% as good, 46.7% as satisfactory, 4.6% as poor, and 1% as very poor, which is lower than the Australian mean of 56% for excellent and good ratings combined  reported having had a family member with breast cancer  between the level of annual income and having a mammogram, suggesting that women with a lower income level were more likely to participate in mammographic screening. Neither English proficiency nor length of residence was significantly related to having a mammogram, although a significant association (P < 0.05) was found between length of residence and having a CBE.Table Knowledge of breast cancer  were examined by descriptive statistics. The most common symptom of breast cancer known by participants was a lump (77.0%), followed by nipple discharge (55.8%), swollen underarms (54.0%), changed size or shape of breasts (52.2%), and redness or dimpling of breast (46.0%). For the treatment options of breast cancer, 77.9% of participants identified surgery, and more than half of them identified chemotherapy (53.1%) and radiation therapy (52.2%). Mammography (66.7%) was the first option identified for detecting breast cancer, then CBE and needle biopsy.t‐tests were used to assess the relationship between breast cancer knowledge and breast cancer screening practices  believed that “cancers are caused by an unhealthy lifestyle.” This belief was not significantly associated with a CBE or mammogram, but the population who believed this were more likely to participate in CBE and mammograms , and the women who perceived “people got breast cancer as they did not breastfeed their babies” were less likely to have a mammogram .More than half of participants (61.8%) indicated that “cancer is hereditary” and 36.2% of participants indicated that “people got breast cancer as they did not breastfeed their babies.” Women who perceived “cancer is hereditary” were more likely to have a CBE , followed by Christian religion . This suggested that participants, who stayed in Australia longer and were Christians, were more likely to have a CBE. For having a mammogram, the length of residence also was the strongest predictor , followed by age  and annual income . This indicated that participants, who stayed in Australia longer, were younger, and had lower annual income, were more likely to have a mammogram.Binary logistic regression was used to assess the impact of the predictors on the likelihood of participating in breast cancer screening tests. Associated factors  or mammogram (69%). However, participants reported higher levels of discomfort (56%), irritation (32%), pain (59%), and embarrassment (29%) with mammograms.4This study investigated the breast cancer screening practices of Chinese‐Australian women in Sydney. The participant group members were fairly typical with a low rate of breast cancer reported, as well as the expected levels of chronic disease and personal health reported. Findings provided an insight into practices and behaviors by examining the associated factors and barriers regarding having a CBE and mammogram. Results indicated that most Chinese‐Australian women had engaged in CBE and mammograms at some stage, but the participation rate in the recommended frequency of breast screening was not high (58.3% for a CBE in the last year and 64.2% for a mammogram in the last 2 years). The participation rate of having a CBE highlighted that most participants had a CBE over a year ago  being overestimated or underestimated by participants, and social desirability bias may be present (van de Mortel, 5Whilst most Chinese‐Australian women had engaged in CBE and mammograms, they were having mammograms as recommended rather than having a CBE regularly. GPs are essential for encouraging women to have a CBE, especially those who are not yet invited to mammography screening. Some participants describe negative experiences of mammograms such as pain, discomfort, irritation, and embarrassment, which may discourage participation in screening tests. Prior to undertaking CBE or mammography, Chinese‐Australian women need to be educated about awareness of their usual breast health to be aware of any changes, especially if women are not eligible for mammography or have difficulty in accessing health services.6Findings have shown that breast cancer screening practices need to be continually promoted to Chinese‐Australian women by health professionals, especially for those under the age of the National free mammography program, and newly arrived migrants. These findings also demonstrate that the situation has continued over time. Chinese migrant women who are not connected to community Chinese organizations may also need to be targeted more actively such as by providing culturally appropriate information (Kwok & White, Study design: Lei Wang, Lynette Mackenzie, Zakia Hossain.Data collection: Lei Wang, Lynette Mackenzie, Zakia Hossain .Data analysis: Lei Wang, Lynette Mackenzie, Zakia Hossain .Manuscript writing: Lei Wang, Lynette Mackenzie, Zakia Hossain .Appendix S1. Supporting Information.Click here for additional data file.


Breast cancer is an umbrella term referring to a group of biologically and molecularly heterogeneous diseases originating from the breast. Globally, incidences of breast cancer has been increasing dramatically over the past decades. Analyses of multiple clinical “big data” can aid us in clarifying the means of preventing the disease. In addition, predisposing risk factors will be the most important issues if we can confirm their relevance. This study aims to provide an overview of the predisposing factors that contribute to a higher possibility of developing breast cancer and emphasize the signs that we ought to pay more attention to.This is a matched nested case-control study. The cohort focused on identifying the eligible risk factors in breast cancer development by data screening (2000-2013) from the Taiwan National Health Insurance Research Database (NHIRD) under approved protocol. A total of 486,069 females were enrolled from a nationwide sampled database, and 3281 females was elligible as breast cancer cohort, 478,574 females who had never diagnosed with breast cancer from 2000 to 2013 were eligible as non-breast cancer controls, and matched to breast cancer cases according to age using a 1:6 ratio.We analyzed 3281 breast cancer cases and 19,686 non-breast cancer controls after an age-matched procedure. The significant predisposing factors associated with breast cancer development including obesity, hyperlipidemia, thyroid cancer and liver cancer. As for patients under the age of 55, gastric cancer does seem to have an impact on the development of breast cancer; compared with their counterparts over the age of 55, endometrial cancer appears to exhibit an evocative effect.In this nationwide matched nested case-control study, we identified obesity, hyperlipidemia, previous cancers of the thyroid, stomach and liver as risk factors associated with breast cancer. However, the retrospective nature and limited case numbers of certain cancers still difficult to provide robust evidence. Further prospective studies are necessitated to corroborate this finding in order to nip the disease in the bud.The studies involving human participants were reviewed and approved by the China Medical University Hospital [CMUH104-REC2-115(AR-4)].The online version contains supplementary material available at 10.1186/s12885-022-09913-6. Over 2.1 million female  are diagnosed with breast cancer every year throughout the world . Written informed consent for participation was waived for this study in accordance with the national legislation and the institutional requirements.Since we want to conduct the comparative approach to the risk of breast cancer development in the fully enumerated cohort, we adopted the nested case-control study design to clarify their correlation. In order to verify the risk of pre-cancer, we set a backtracking period of five-years from the time of breast cancer diagnosis, and identified the diseases that were treated and meet the definition of ICD-9 code and identified at least three outpatient visits or one hospitalization. Of the 1 million samples, 486,069 females were enrolled, and 3281 females who was newly diagnosed with breast cancer (ICD-9-CM code 174) within 5 years after first observed date between 1 January 2005 and 31 December 2013, and obtained registry for catastrophic illness was eligible in breast cancer cohort. The first breast cancer diagnosis date was used as the index date for breast cancer cases. 478,574 females who had never diagnosed with breast cancer from 2000 to 2013 were eligible as non-breast cancer controls, and matched to breast cancer cases according to age using a 1:6 ratio. An index dates was set at the fifth year after the initial date of observation for non-breast cancer cohort. Hence, 19,686 matched controls were eligible in later analysis. The study flowchart was summarized in Fig.The baseline characteristics were age, gender, hypertension (ICD-9-CM codes 401-405), hyperlipidemia (ICD-9-CM codes 272.0-272.4), chronic liver disease (ICD-9-CM code 571), chronic kidney disease (ICD-9-CM code 585), diabetes (ICD-9-CM code 250), chronic obstructive pulmonary disease , autoimmune disease , cardiovascular disease (ICD-9-CM codes 410-414), stroke (ICD-9-CM codes 430-438), endometriosis (ICD-9-CM code 617), and obesity (ICD-9-CM code 278). Furthermore, we also obtained data of patients with cancers that may be related, such as colorectal cancer , lung cancer (ICD-9-CM code 162), thyroid cancer (ICD-9-CM code 193), liver cancer (ICD-9-CM code 155), cancer of the corpus uteri (ICD-9-CM code 182), ovary cancer (ICD-9-CM code 183), cervical cancer (ICD-9-CM code 180), skin cancer , and stomach cancer (ICD-9-CM code 151). The ICD-9-CM code for above mentioned disease were summarized in Supplementary Table SP values were two-sided and P < 0.05 was considered statistical significance. All statistics was performed using SPSS version 18.0 .The chi-squared test or Student’s t-test was used to compare the demographic characteristics of breast cancer cases and non-breast cancer controls as appropriate. Conditional logistic regression was used to estimate the risk of breast cancer development in different cancer types, the odds ratio (ORs) and confidence interval (CI) were computed. In addition, since breast cancer is related to hormonal regulation, we added the average age of menopause at 55 years of age as a boundary to further clarify whether the age factor can be found to be related to the development of breast cancer from other cancer survivors. All In this case-control study, 486,069 females were included. Of these, 3281 individuals were afflicted with breast cancer, the rest were those who were not, but still had other chronic diseases or other types of cancer. The risk of developing breast cancer was elevated among the disease of hyperlipidemia and obesity (Table P = 0.030). Obesity is confirmed by the outpatient physician who obtained the ICD-9-CM codes as 278, which is generally a stricter definition. Although the number of breast cancer patients who meet obesity standards is 30, there are still obvious differences in risk compared with non-breast cancer patients. Hyperlipidemia also has a significant influence on the development of breast cancer (P = 0.002).According to the study findings shown in Table P = 0.034). After adjusted by conditional logistic regression, the estimated OR of thyroid cancer was 1.82 (95% CI = 1.02-3.25), still remained significant higher risk in breast cancer development. In addition, liver cancer also showed significant higher risk in the future development of breast cancer, and the estimated OR was 1.78 . As for the age adjusted subgroup analysis (Table P = 0.048). For the opposing group consisting of those aged younger than 55, stomach cancer victims were reported to have a slightly significant higher risk of getting breast cancer with an OR of 7.45 . Of notes, although a great odds of high incidence risk of breast cancer have been estimated for the stomach cancer victims, a conservative used of current results is suggested. To further clarify the potential effects varied by age, the conditional logistic regression subgroup analysis using an age cut-off value of 50 years old were summarized in Supplementary Table SP = 0.003) was significant associated with the increasing risk of breast cancer development, which is consistent with the results found in age ≥ 55 years subgroup. In addition, although cancer of corpus uteri showed an potential increasing risk on breast cancer development, no statistical significance was estimated in age ≥ 55 years subgroup.According to the results of univariate analysis as shown in Table Obesity is a recognized risk factor for the development of breast cancer and its recurrence even when patients are treated appropriately . Excessip-value = 0.002). Nevertheless, further studies and literary reviews are needed to clarify the disparity in the findings in order to confirm the effect of cholesterol and its treatment on the etiology of breast cancer.Hyperlipidemia, high blood cholesterol, is a common comorbidity to obesity . There iCancer survivors can be affected by a number of health problems, but often their greatest concern is facing cancer again. Some cancer survivors may develop a new, unrelated cancer later on in life. We wanted to clarify which distinct cancers have connections to breast cancer, so we used the benefit of big data analyses to find the connection and discussed it further.Thyroid cancer starts when healthy cells in the gland mutate and grow out of control. Breast and thyroid cancers are two malignancies with the highest incidence in female. These cancers often occur metachronously which means the two cancers have a successive relationship and occur more than 6 months later from the first episode based on Moertel’s definitions . The risBased on our analysis, liver cancer survivors and secondary breast cancer had a significant correlation but has seldom been demonstrated before. The traceable reported case is a patient with hepatitis B who developed a tumor mass of the liver and was presented with right breast nodule at the same time . From thAs for primary liver cancer (PLC), there is an unfavorable increasing trend observed in most developed countries, obesity and buildup of fat in the liver due to western dietary habits is the major reason of this tendency . In otheBRCA1/2 gene are five times more likely to develop breast cancer than someone without a mutation [BRCA1/2 mutations have been reported to increase the lifetime risk of developing stomach cancer by as much as 6 folds among first-degree relatives of BRCA1/2 mutation carriers [Stomach cancer is a genetically heterogeneous tumor with multifactorial etiologies, associated with environmental and genetic factors. We believe that if the two cancers share common genetic influence, there may be a positive correlation between the occurrence. BRCA1/2 and CDH1 (E-Cadherin) are genes that are evident in the literature review. First, females with a mutated mutation . Stomachcarriers . Second,carriers . Other rcarriers . If obesCancer of corpus uterine  begins in the layer of cells that from the lining of the uterus. The known risk factors are hormone related, such as early menarche or late menopause, nullipara, irregular menstrual periods and obesity. Exogenous hormones can increase the risk of developing endometrial cancer. A large retrospective meta-analysis in German and Swedish Cancer Registry discovered that elevated risks were present on second ovarian endometrial carcinoma and secondary kidney cancer for 3973 endometrial cancer survivors , nothingThe enrolled samples reviewed in this study have three potential limitations. The first relates to the size of some comparison groups, especially for cancer survivors. Since we set strict conditions for the continued development of cancer, some cancers have only single digits, such as cancer of corpus uteri, ovary cancer, skin cancer and stomach cancer. These samples were too small to precisely detect risk factors with low prevalence number. The second limitation is the background population, they were all restricted to the same race and a single country. It cannot be completely regard as the tendency of most people. The third limitation relates to self-reported data which can introduce a bias. Take obesity for example, its association with hormone related cancers has been accepted, but obesity is not commonly diagnosed as a disease, unless interventional treatment, such as surgery, is required. Therefore, the input of this ICD-9-CM code may be indirectly underestimated. The same incident may easily occur on the input of some chronic diseases. Moreover, the analysis data of current study were only retrospectively abstracted from the outpatient visits, emergency admission, and hospitalization records registered in Taiwan’s NHIRD, the individual information including genetic factors and family history for study cohort, and tumor characteristics for cancer patients are not available. Despite this, this study still provided a nationwide evidence to identify predisposing risk factor associated with breast cancer development, and carefully discussed the potential association between the predisposing factors and breast cancer development according to the our study findings.To sum up, this article has presented a retrospective nationwide matched nested case-control study based on the basic concept of “Big Data” integration, and further revealed several predisposing factors associated with breast cancer incidence risk. Breast cancer prevention requires raising awareness among those possible predisposing risk factors. However, the retrospective nature and limited case numbers of certain cancers still difficult to provide robust evidence. Therefore, further prospective research and investigation need to be carried out in order to achieve greater consensus.Additional file 1: Supplementary Table S1. The ICD-9-CM code for all analyzed diseases.Additional file 2: Supplementary Table S2. Conditional logistic regression subgroup analysis for predisposing risk factors of breast cancer development.


To develop and evaluate the screening performance of a low-cost high-risk screening strategy for breast cancer in low resource areas.Based on the Multi-modality Independent Screening Trial, 6 questionnaire-based risk factors of breast cancer  were used to determine the women with high risk of breast cancer. The screening performance of clinical breast examination (CBE), breast ultrasonography (BUS), and mammography (MAM) were calculated and compared to determine the optimal screening method for these high risk women.P = 0.002]. Compared with MAM, BUS showed significantly higher specificity , but no significant differences in sensitivity [68.75% (33/48) vs. 73.91% (34/46)], positive prediction values [18.54% (33/178) vs. 14.11% (34/241)], and negative prediction values [99.86%  vs. 99.89% ]. Further analyses showed no significant difference in the percentages of early stage breast cancer [53.57% (15/28) vs. 50.00% (15/30)], lymph node involvement [22.73% (5/22) vs. 28.00% (7/25)], and tumor size ≥ 2 cm [37.04% (10/27) vs. 29.03% (9/31)] between BUS and MAM. Subgroup analyses stratified by breast densities or age at enrollment showed similar results.A total of 94 breast cancers were detected among 31,720 asymptomatic Chinese women aged 45–65 years. Due to significantly higher detection rates (DRs) and suitable coverage of the population, high risk women were defined as those with any of 6 risk factors. Among high risk women, the DR for BUS  was similar to that for MAM , while it was significantly higher than that for the CBE [1.73/1,000 , The low-cost high-risk screening strategy based on 6 questionnaire-based risk factors was an easy-to-use method to identify women with high risk of breast cancer. Moreover, BUS and MAM had comparable screening performances among high risk women. It is the most common cancer in women, both in more and less developed regions, with slightly more cases in less developed than in more developed regions3. Moreover, breast cancer mortality rates have been stable or decreasing since around 1990 in North America and high resource European countries, while the mortality rates have shown no obvious decrease, but rather potential increases in low resource countries, such as China, due to unique physiological and reproductive characteristics, dramatic lifestyle changes associated with westernization, and the delayed introduction of effective breast cancer screening programs11.Breast cancer is the most common cancer in the world, with an estimated 2.3 million new cases diagnosed in 2020 13. Due to limited resources and the relatively low incidence of breast cancer14, it is not appropriate to conduct general population-based screening in low resource areas, such as China. On the contrary, high risk population-based screening may be a more suitable choice for China. According to guideline recommendations from the American Cancer Society, the U.S. Preventive Services Task Force, National Comprehensive Cancer Network (NCCN), and the American College of Radiology (ACR)18, women with high risk of breast cancer were usually defined as women with known underlying genetic mutations , extremely dense breasts on MAM, or other complex risk prediction models. For residents in low resource areas, it would be cost-prohibitive to conduct tests of BRCA gene mutations, tumor biomarkers, and other blood markers before screening, while it would be also impractical to determine complex cancer risk predictions before screening. Development of a low cost, easy-to-use, and relatively scientific high risk screening strategy would be the preferred choice for low resource areas, such as China.Several studies suggested that general population-based mammography (MAM) screening could reduce breast cancer mortality10. Due to several objective reasons, such as the inaccessibility of MAM equipment, the lack of insurance coverage, and the lack of professional screening technicians, it is impractical to conduct MAM-based breast cancer screening in low resource areas14. In China, MAM also seems to be less attractive compared to breast ultrasonography (BUS) in low resource areas due to potential radiation risks, over diagnosis, and less sensitivity of suspicious breast cancers in women with small and dense breasts22. More recently, several studies reported that BUS showed comparable screening performances compared to MAM in high risk women22. However, as mentioned above, high risk women were mainly defined by complex models or high cost tests. Few studies have determined whether the screening performances of BUS are also comparable to MAM among high risk women as defined by low cost methods.Until now, there has been no consensus on which breast cancer screening method is more suitable for Asian women, when compared to European or American womenBased on the Multi-modality Independent Screening Trial (MIST) of breast cancer in China, we therefore aimed to develop a low-risk, easy-to-use, and relatively scientific method for identifying women at high risk of breast cancer, and then to determine the optimal screening methods for these women in low resource areas.23. Briefly, a total of 33,234 asymptomatic women who were aged 45~65 years and lived in local communities for more than 3 years were recruited from 5 areas in China  between July 2008 and December 2010. After obtaining informed consent, all participants received a face-to-face questionnaire-based interview conducted by local investigators to collect information on demographic characteristics , family history of cancer, history of benign breast disease, and factors associated with breast cancer risk, including age of the first menarche, menopausal status, age at menopause, abortion, giving births, breast feeding, oral contraceptive use, and hormone replacement therapy. Body weight (kg) and height (m) were measured by trained investigators, and the body mass index was calculated as the weight in kg divided by the square of height in meters (kg/m2). This study was reviewed and approved by the institutional review board of Tianjin Medical University Cancer Institute and Hospital (TMUCIH).MIST aimed to evaluate and compare the screening performances of clinical breast examinations (CBEs), BUS, and MAM among Chinese women aged 45~65 years, and to identify a suitable breast cancer screening strategy for targeted women. Detailed information of MIST has been described in our previously reportsAfter a questionnaire-based interview, all participants received CBE, BUS, and MAM. The physicians performed these 3 examinations blindly and separately. All physicians had at least 5 years of work experience regarding the corresponding examinations. All examinations followed unified technical protocols developed by the expert committees of MIST. Bilateral MAM was conducted with a full-field digital mammography system. Bilateral BUS was performed with color Doppler and high resolution transducers with a maximum frequency of at least 10 MHz.23.The results of these 3 examinations, including breast mass, calcification, breast density, and other imaging characteristics, were recorded in predesigned case report forms. The results of CBE and BUS were assessed categorically as follows: 1) normal; 2) abnormal benign; 3) suspicious malignancy; and 4) highly suggestive of a malignancy. The results of MAM were assessed according to the Breast Imaging Reporting and Data System of the American College of Radiology (ACR): 0) additional imaging needed; 1) negative; 2) benign finding; 3) probably benign finding; 4) suspicious malignancy; and 5) highly suggestive of a malignancy. All assessments of MAM and BUS were double-checked at primary screening sites. Disagreement between 2 MAM physicians was reassessed by another more experienced MAM physician, while disagreement between 2 BUS physicians was also reassessed by another more experienced BUS physician. Moreover, a subsample of MAM images was sent to TMUCIH for concordance analyses. Detailed information of these methods can be found in our previously published papersPatients with suspicious malignancies and highly suggestive of breast cancers from any of the abovementioned 3 examinations were immediately recommended for pathological examination. The diagnosis of breast cancer was based on combinations of pathological examinations, clinical diagnoses, or follow-ups within 1 year after the initial screenings. For all breast cancers confirmed by the reference standards, clinical data on tumor characteristics  were obtained from pathological reports. The tumor stage was defined according to the American Joint Committee on Cancer Tumor Node Metastasis staging system.29. However, as mentioned above, high risk women were mainly defined by complex models, and the utility of these complex breast cancer risk assessment models was very low. Lack of familiarity was the most cited barrier in the use of these complex risk prediction models31. Instead of developing a complex risk prediction model, the number of known risk factors of breast cancer was therefore used to identify potential high risk women in this study.Several risk prediction models have been previously developed to identify the potential high risk population of breast cancers34, a total of 13 factors  were initially selected. After excluding correlated factors, factors with risk frequencies ≥ 20% (to avoid labeling too many women as “high-risk groups”)19, and factors with missing values ≥ 5%, 6 target factors  were finally selected . Among 33,234 participants, after excluding 1,514 (4.6%) women with missing values of the 6 abovementioned target factors, 31,720 women were included in the final analyses.According to our previous studies and other comprehensive studies on the risk factors of breast cancer among Chinese womenvs. MAM among high risk women by age at enrollment or by breast density.Pearson’s chi-squared tests and Fisher’s exact tests were used to determine the differences in breast cancer detection for different high-risk screening strategies with different numbers of breast cancer risk factors. Both the breast cancer detection and population coverage of different high-risk screening strategies were used to determine the optimal strategy for defining high risk populations of breast cancer. Among high risk women, Pearson’s chi-squared tests and Fisher’s exact tests were further used to compare breast cancer detection rates for 3 different screening methods . Pearson’s chi-squared and McNemar’s chi-squared tests with continuity correction were used to compare the screening accuracy  and tumor characteristics  of 3 screening modalities  among high risk women. Subgroup analyses were further conducted to compare the sensitivities of BUS P < 0.05 was considered statistically significant.All the analyses were conducted with R software, version 3.6.2  and SPSS statistical software for Windows, version 24 . Two-sided Supplementary Table S1. As shown in Supplementary Table S2, the detections were 2.23/1,000 , 4.19/1,000 , 4.49/1,000 , and 9.17/1,000 (2/218) for women with 0, 1, 2, and ≥ 3 risk factors, respectively (P = 0.011).A total of 94 breast cancers were detected among 31,720 asymptomatic Chinese women aged 45–65 years. The characteristics of the population and their corresponding detection of breast cancer are shown in P = 0.005). However, the percentage of the included population to the whole population was only 6.31%, while a total of 89.36% (84/94) cancers were missed (Supplementary Table S2). We therefore redefined the high risk women as those with any 1 of the 6 listed risk factors. The detection among high risk women  was still significantly higher than that among low risk women  (P = 0.001) , with 34.89% for the high risk population relative to the entire population . Due to the high detection of breast cancer and relatively suitable coverage of the whole population, the high risk women in this study was finally defined as women who had any of the 6 questionnaire-based risk factors.Among women with ≥ 2 risk factors, the detection  was significantly higher than that among women with < 2 risk factors ] was similar with that for MAM , while it was significantly higher for CBE . Therefore, in order to determine the optimal screening method for high risk Chinese women, the following comparisons of screening performances were conducted between MAM and BUS.As shown in Supplementary Table S3), compared with MAM, BUS showed significantly higher specificities , but no significant differences in sensitivity , PPV , and NPV .Among screening-detected cancers (vs. 50.00% (15/30), P = 0.993], lymph-node involvements , and tumor size ≥ 2 cm  for BUS and MAM, respectively (Supplementary Table S4).Further analyses also showed no significant differences in the characteristics of screening-detected cancers between BUS and MAM, including the percentages of early stage (stage 0 + I) breast cancer: [53.57% (15/28) P = 0.794), 51%–75% (P = 0.979), and > 75% (P = 0.059), respectively. Further analyses showed no significant difference of sensitivities between MAM and BUS across 4 subgroups of breast densities, with the sensitivities being 100% (5/5) vs. 60% (3/5) for women with breast densities of 0 < 25% (P = 0.444), 66.67% (12/18) vs. 77.78% (14/18) for women with breast densities of 25%–50% (P = 0.457), 81.25% (13/16) vs. 68.75% (11/16) for women with breast densities of 51%–75% (P = 0.414), and 66.67% (2/3) vs. 33.33% (1/3) for women with breast densities of > 75% (P = 1.000) (Supplementary Table S5).Among high risk women, there was no significant difference in the detection between women with different breast densities, with detections of 3.58/1,000 , 4.65/1,000 , 4.27/1,000 , and 4.26 (3/704) for women with breast densities of 0 < 25% (using control group), 25%–50% (P = 0.794), 55–59 years (P = 0.979), and ≥ 60 years (P = 0.059), respectively. Further analyses also showed no significant difference of sensitivities between MAM and BUS across 4 subgroups of ages at enrollment, with sensitivities of 73.33% (11/15) vs. 60.00% (9/15) for women aged ≤ 49 years (P = 0.439), 72.73% (8/11) vs. 45.45% (5/11) for women aged 50–54 years (P = 0.193), 87.50% (7/8) vs. 80.00% (8/10) for women aged 55–59 years (P = 1.000), and 66.67% (8/12) vs. 91.67% (11/12) for women aged ≥ 60 years (P = 0.317) (Supplementary Table S5).Among high risk women, there was also no significant difference in detection between women with ages at enrollment, with detection of 3.88/1,000 , 3.50/1,000 , 3.92/1,000 , and 7.93  for women with ages at enrollment ≤ 49 years (Control group), 50–54 years . Moreover, based on the International Agency for Research on Cancer (IARC) Working Group and systematic reviews on the benefits and harms of breast cancer screening50, methods which could detect more invasive but node-negative cancers would be preferred in the future to avoid potential over diagnosis, especially in regions or countries with limited social resources. Based on the results of our study and previous studies, BUS is more preferred than MAM for high risk Chinese women according to the abovementioned prerequisites. However, more studies are needed in the future to support BUS screening.In addition to the easy-to-use high risk definition method, the more important implication of our study was the similar screening performances of BUS and MAM among high risk Chinese women, which were also reported in the ACRIN 6666 and the study by Shen et al.vs. MAM among high risk Chinese women. First, Chinese women tend to have smaller and more dense breasts than Americans in a younger age group10, which has been reported to reduce the sensitivity of MAM51. Second, the peak age at diagnosis of breast cancer among Chinese women was nearly 10–20 years younger than that in American women14, and MAM was also less effective in younger women compared with older women52. Third, BUS had more potential to detect node-negative and invasive breast cancers than MAM in young women or women with dense breasts20. We also observed similar results in the subgroup analyses. However, we did not find significant advantages for BUS vs. MAM among Chinese young women or women with dense breasts. Small sample size was the probable reason. Moreover, we were not the first to report these results. In the ACRIN 6666 study, although BUS was more likely to detect node-negative and invasive cancers than MAM, there was also no significant difference in the screening sensitivities of BUS vs. MAM among young women or women with dense breasts. More studies in the future are therefore needed to confirm the reasons for the similar performances of BUS vs. MAM among high risk women.Several reasons could explain the similar performances of BUS Supplementary Table S2, a total of 46 cancers were reported among 20,654 participants with 0 risk factors. In the future, these individuals should be initially screened by combining traditional cancer risk assessment, genetic risk assessment, tumor markers, or other routine indicators (such as blood lipids) to avoid potential missed diagnoses. In addition, as shown in Supplementary Table S1, significant differences in the detection of breast cancer in different subgroups were only found for AGEMENO and FHBC, but not for the other 4 variables. This limitation was probably caused by too few cases and too many healthy participants in the screening studies, where it is often impossible to confirm all significant associations observed in case-control studies. Second, to develop a feasible high risk screening strategy for breast cancer in low resource areas, it is necessary to conduct health economics evaluations based on the effectiveness and costs of screening. However, this study did not collect necessary cost information required in cost evaluations, such as the time cost for participating in screening, the cost of further diagnostic examinations and treatment for screening-detected cancer patients, and the comparable costs of treatments for patients diagnosed in clinical visits rather than by screening during the same period. The current results were therefore not available for health economics evaluations. More studies are needed in the future to explore the cost-effectiveness ratio of this high risk screening strategy. Third, due to the lack of long-term follow-ups, it was impossible to evaluate the impact of the high risk screening strategy proposed in this study on breast cancer mortality. However, as reported in the latest cancer registry report in China, the crude breast cancer incidence was 45.29 per 100,00053, which was significantly lower than the detection of breast cancer  in our study . The percentage of early stage breast cancer in our study  was also significantly higher than that among clinically-diagnosed breast cancer (20.1%)54. Based on the high detection and the high percentage of early stage breast cancers, we can expect that the high risk screening strategy proposed in this study will lead to a reduced breast cancer mortality in the future.In addition to the aforementioned findings, this study also had certain limitations. First, although we proposed an easy-to-use method with 6 risk factors to identify potential high risk women, missed diagnoses were inevitable, as shown in In summary, we have proposed an easy-to-use high-risk screening strategy for breast cancer. BUS showed similar screening performances with MAM in the cancer detection, accuracy, and tumor characteristics among Chinese high risk women. Although further validation studies are needed to confirm these results, this study suggested that BUS is a potentially preferable method, when compared to MAM for high risk Chinese women, particularly in regions where there is a lack of MAM equipment but with more BUS systems.Click here for additional data file.


Breast cancer is a serious threat to female health, and its incidence varies with education level (EL). In the present study, the association between EL and the risk of developing female breast cancer was investigated.From May 2006 to December 2007, 20,400 observation subjects in Kailuan Cohort received questionnaires and were subjected to clinical examinations for data collection on baseline population characteristics, height, weight, lifestyle and past disease history. Then, these participants were followed up with from the date of recruitment to December 31, 2019. Cox proportional risk regression models were used to analyse the association between EL and the risk of developing female breast cancer.The cumulative follow-up period of 20,129 observation subjects that meet the inclusion criteria of this study was 254,386.72 person-years, and the median follow-up time was 12.96 years. During the follow-up period, 279 cases of breast cancer were diagnosed. In comparison with the low EL group, the risk of developing breast cancer was significantly higher in the medium  = 2.23 (1.12–4.64)] and high [HRs (95% CI) = 2.52 (1.12–5.70)] EL group.An increased risk of breast cancer was associated with a higher EL, and some certain factors, such as alcohol use and hormone therapy, may play a mediating role. Breast cancer poses a serious threat to female health worldwide. Based on GLOBOCAN data, in 2020 alone, the number of new cases of breast cancer reached 2.26 million, and the incidence of breast cancer ranks first among female malignant tumours . AlthougNotably, the incidence of malignant tumours varies with the education level (EL). A negative correlation has been observed between EL and the risk of developing gastric, liver, lung, and oesophageal cancer in humans , 5, the The Kailuan Study, which began in 2006, is an ongoing observational cohort study of a functional community population. The EL information of the Kailuan Study subjects was obtained at baseline (from May 2006 to December 2007). Then, continuous follow-up data, including breast cancer data, were obtained from the establishment of the cohort to the present, allowing us to study the association between EL and breast cancer. More details about the Kailuan Study can be found in the literature , 9. Subj2 (m2).Face-to-face questionnaire interviews and health examinations were performed by well-trained physicians or nurses by using a standardized protocol to gather information at baseline. These baseline data included sociodemographic characteristics , lifestyle characteristics , history of previous diseases  and physical examination data (height and weight). Participants were asked to take off their hats and shoes and wear thin clothes during the measurement. Height and weight were measured, and body mass index (BMI) was calculated as weight (kg)/heightEL was classified into three categories, namely, low EL (illiteracy and primary), medium EL (middle school) and high EL (college and above). Smoking was defined as smoking one or more cigarettes per week in a recent year, and participants were classified into never smokers, former smokers and current smokers. Alcohol drinking was defined as drinking one or more alcoholic drinks per month for no less than six consecutive months, and participants were classified into never drinkers, former drinkers and current drinkers. Physical activity was classified according to the frequency of physical activity (20 min = 1 instance of activity) performed during leisure time. The categories of physical activity include exercise occasionally (< four instances of activity per week) and frequent exercise (≥ four instances of activity per week).The follow-up period was considered from the establishment of Kailuan Cohort (May 2006 – December 2007) to December 31, 2019. The follow-up endpoint was newly diagnosed breast cancer or death in the observed subjects (whichever came first). First, information on the participant medical records was obtained through the Tangshan City health insurance system. Then, the medical histories of subjects were collected by professionally trained investigators. Pathology, imaging  and blood biochemical examination results were verified by clinicians to confirm the diagnosis of breast cancer. Tumour cases were coded according to the International Classification of Diseases-10 (ICD-10), and breast cancer was coded as C50. Information on fatal events was obtained from the Kailuan Group social insurance system.P < 0.05 (two-sided).SAS 9.4 was used to perform statistical analysis of the data. Continuous variables were expressed as mean ± standard deviation, while categorical variables were expressed as the number of cases (percentage). Differences in baseline demographic characteristics among the low, medium and high EL groups were analysed using variance analysis and Chi square test. A multivariable Cox proportional hazards regression model was applied to analyse the associations between EL and the risk of developing breast cancer. Subgroup analysis was performed according to age, BMI, physical activity and hypertension history, and the associations between EL and the risk breast cancer were explored in different subgroups. Sensitivity analysis was conducted to evaluate the consistency of our findings after excluding participants new breast cancer within 2 years of the start of the follow-up period. All statistical tests were considered statistically significant at P values < 0.0001; Table The number of female participants in the 2006 baseline survey was 20,400. A total of 116 individuals with a history of malignancy and 155 participants lacking baseline EL data were excluded, and 20,129 female participants were eventually included in the statistical analysis. The mean age of the observed subjects was 48.75 ± 11.50 years. The low, medium and high EL groups included 1,078, 16,833 and 2,218 subjects, respectively. In comparison to the medium- and high-EL groups, the mean age, BMI and the proportions of subjects with current smoking, heavy salt intake, frequent physical activity, hypertension and diabetes were higher in the low EL group, whereas the proportions of current drinkers were lower  were detected during the follow-up period. Cox proportional risk regression analysis was carried out with the occurrence of breast cancer as the dependent variable and EL difference as the independent variable. In comparison with the low EL group, model 1 was adjusted for age, while model 2 was adjusted for smoking, alcohol consumption, BMI, physical activity, salt intake, hypertension and diabetes mellitus based on model 1. The hazard ratios (HRs) and 95% confidence intervals (95% CI) for breast cancer in the medium and high EL group were 2.23(1.12–4.64) and 2.52(1.12–5.70), respectively. In the sensitivity analysis, after excluding participants who developed breast cancer within 2 years after the start of the follow-up period, the risk of breast cancer was significantly higher in the medium and high EL group . The larger study cohort and longer follow-up time aims to minimise the effect of the above missing factors, and the abovementioned variables will be increased in subsequent studies. Secondly, only baseline data of EL were used for the analysis of the association between EL and breast cancer risk, and time-dependent exposures during follow-up were not considered. Some subjects may have received on-the-job education, so changes in EL may affect the risk of developing breast cancer, which should be explored in depth in subsequent studies.An increased risk of breast cancer was associated with a higher EL. This condition was more prominent in the sensitivity analysis, and certain factors such as alcohol use and hormone therapy may play a mediating role. Breast cancer can be reduced by reducing alcohol intake, maintaining a normal BMI, controlling blood pressure, increasing physical activity and improving screening compliance.


Breast cancer incidence rates have not declined despite an improvement in risk prediction and the identification of modifiable risk factors, suggesting the need to identify novel risk factors and etiological pathways involved in this cancer. Metabolomics has emerged as a promising tool to find circulating metabolites associated with breast cancer risk.Untargeted metabolomic analysis was done on prediagnostic plasma samples from a case–cohort study of 1695 incident breast cancer cases and a 1983 women subcohort drawn from Cancer Prevention Study 3. The associations of 868 named metabolites (per one standard deviation increase) with breast cancer were determined using Prentice-weighted Cox proportional hazards regression modeling.A total of 11 metabolites were associated with breast cancer at false discovery rate (FDR) < 0.05 with the majority having inverse association [ranging from RR = 0.85 (95% CI 0.80–0.92) to RR = 0.88 (95% CI 0.82–0.94)] and one having a positive association [RR = 1.14 (95% CI 1.06–1.23)]. An additional 50 metabolites were associated at FDR < 0.20 with inverse associations ranging from RR = 0.88 (95% CI 0.81–0.94) to RR = 0.91 (95% CI 0.85–0.98) and positive associations ranging from RR = 1.13 (95% CI 1.05–1.22) to RR = 1.11 (95% CI 1.02–1.20). Several of these associations validated the findings of previous metabolomic studies. These included findings that several progestogen and androgen steroids were associated with increased risk of breast cancer in postmenopausal women and four phospholipids, and the amino acids glutamine and asparagine were associated with decreased risk of this cancer in pre- and postmenopausal women. Several novel associations were also identified, including a positive association for syringol sulfate, a biomarker for smoked meat, and 3-methylcatechol sulfate and 3-hydroxypyridine glucuronide, which are metabolites of xenobiotics used for the production of pesticides and other products.Our study validated previous metabolite findings and identified novel metabolites associated with breast cancer risk, demonstrating the utility of large metabolomic studies to provide new leads for understanding breast cancer etiology. Our novel findings suggest that consumption of smoked meats and exposure to catechol and pyridine should be investigated as potential risk factors for breast cancer.The online version contains supplementary material available at 10.1186/s13058-023-01602-x. Breast cancer is the most commonly diagnosed cancer and the second leading cause of cancer death among women in the USA . DespiteMetabolomics provides a comprehensive assessment of the small molecules in a blood sample that integrates the effects of endogenous metabolism, exogenous exposures, and genetic variation. Recently, this technology has been used in prospective cohort studies to identify metabolites associated with breast cancer risk. To date, there have been ten studies from seven prospective cohorts that have applied metabolomics to prediagnostic blood samples from breast cancer cases and controls –13. ThesIn this study, we conducted a large prospective case–cohort analysis among 1695 breast cancer cases and a randomly selected subcohort of 1983 participants drawn from women enrolled in the Cancer Prevention Study-3 (CPS-3). Relative levels of 868 known metabolites were measured using an untargeted, MS-based metabolomics platform to maximize the chance of our findings overlapping with those of other studies and to discover novel metabolites associated with breast cancer risk.The women in this study were from the CPS-3, a prospective study of cancer incidence and mortality among approximately 300,000 adults. CPS-3 participants were cancer-free, between the ages of 30 and 65, and from 35 states, Puerto Rico, and Washington DC at the time of enrollment between 2006 and 2013. Details about enrollment and cohort characteristics are available elsewhere . All parN = 9534), who were not female , had prevalent cancer other than nonmelanoma skin cancer (N = 2248), lived in a state not covered in our cancer registry linkage at the time of this analysis , were missing birth date (N = 64), and whose enrollment was revoked or otherwise compromised (N = 166). From the 205,595 women who remained, 1695 were identified as having been diagnosed with invasive breast cancer between enrollment and December 31, 2015, through linkage to 36 state cancer registries. We also selected a random subcohort of 1983 women from the women eligible for the analysis, of whom 14 developed invasive breast cancer after enrollment. Comparison of the basic characteristics of subcohort with those of all the women in CPS-3  differed significantly (-DC*] difp < 0.05) by time between blood draw and diagnosis, thus limiting any conclusions as to whether any of metabolite levels might be affected by reverse causation.A significant portion of the cases in this study were diagnosed with breast cancer within a few years after the blood collection, while others occurred later in follow-up, allowing us to explore if associations varied by time between blood collection and diagnosis. Only two metabolites had associations that varied significantly (Although all the risk estimates remained similar, adjustment for BMI attenuated the associations of all the metabolites with breast cancer. This could indicate that BMI is a mediator of the associations. If so, then adjustment for BMI may be inappropriate. This possibility should be investigated further in future analyses.A strength of this study is the large study population and the large number of identified metabolites measured. The factors likely contributed to our finding of 11 metabolites associated with breast cancer risk at FDR < 0.05, which is more than previous studies which identified one or two metabolites at most at this significance level , 10. LimThis metabolomic study of breast cancer further replicated positive associations for several steroid metabolites that had been previously replicated and provided new replications for inverse associations for some lipids and amino acids. We also found novel associations for some metabolites which suggest new avenues for investigation into potentially modifiable risk factors for breast cancer. The associations of metabolites of syringol, catechol, and pyridine with increased breast cancer risk suggest future etiologic research should focus on smoked meat consumption and exposure to some chemicals found in our environment. Finally, the growing evidence that larger metabolomic studies are needed to identify robust associations suggests that additional studies and pooled analyses of existing results are needed.Additional file 1: Figure 1. Hierarchical heat map based on Pearson correlation coefficients of metabolites associated with breast cancer at FDR < 0.20 in analyses adjusted for age, race, education, family history of breast cancer, age at menarche, OC use, and parity.