Isoflavones are secondary plant constituents of certain foods and feeds such as soy, linseeds, and red clover. Furthermore, isoflavone-containing preparations are marketed as food supplements and so-called dietary food for special medical purposes to alleviate health complaints of peri- and postmenopausal women. Based on the bioactivity of isoflavones, especially their hormonal properties, there is an ongoing discussion regarding their potential adverse effects on human health. This review evaluates and summarises the evidence from interventional and observational studies addressing potential unintended effects of isoflavones on the female breast in healthy women as well as in breast cancer patients and on the thyroid hormone system. In addition, evidence from animal and in vitro studies considered relevant in this context was taken into account along with their strengths and limitations. Key factors influencing the biological effects of isoflavones, e.g., bioavailability, plasma and tissue concentrations, metabolism, temporality , and duration of isoflavone exposure, were also addressed. Final conclusions on the safety of isoflavones are guided by the aim of precautionary consumer protection.The online version of this article (10.1007/s00204-018-2279-8) contains supplementary material, which is available to authorized users. Isoflavones are secondary plant constituents mainly occurring in soy and red clover. Soy bean, soy germ, and red clover extracts or other isoflavone-containing preparations are marketed, e.g., as food supplements as well as ‘dietary foods for special medical purposes’ and other commodities and are available over the counter in pharmacies, health food shops, supermarkets, and on the internet. According to the European Food Safety Authority (EFSA) EFSA  and the The Permanent Senate Commission on Food Safety of the German Research Foundation (SKLM) evaluated the safety of isoflavones in food supplements and in supplemental balanced diets in 2006 and 2009 thymidine. Specimens for further investigation of these markers can be obtained by conducting a random fine needle aspiration (rFNA). However, it has to be carefully controlled that relevant and representative specimens are sampled from the entire tissue.3H]thymidine or Ki-67 LI  or a normal diet (n = 29), an increase in the breast epithelial cell proliferation rate ([3H]thymidine and Ki-67 labelling) was initially observed   in 48 premenopausal women, either ingesting 45 mg of isoflavones per day (n = 26) or a placebo (n = 25) for 3 months  or placebo (n = 49) per day for 6 months  but not in untreated premenopausal women . However, the authors did not report any statistically significant differences when comparing the median change in Ki-67 LI between treated and control premenopausal women . Mid-luteal phase timing of the menstrual cycle was confirmed by rFNA in 81% of the participants. Menstrual phase remained unclear for the rest .In a randomised, double blind, placebo-controlled intervention study, healthy pre- and postmenopausal women ingested 235 mg isoflavones  volume or endpoints that may provide further information on cellular processes being modulated by isoflavones, such as the influence on the DNA methylation pattern, estrogen metabolism, changes in genetic markers of breast cancer risk, growth factors and cell signalling, markers of oxidative stress and markers of inflammation/immune response. The relevance of these parameters regarding breast cancer development and progression is unclear. Nevertheless, the results of intervention studies dealing with endpoints other than mammographic density or Ki-67 and thymidine labelling index in healthy women were also considered (summarised in Online Annex: chapter II). The available studies reported conflicting results, which at present do not allow drawing firm conclusions on whether isoflavones are indeed able to influence the aforementioned parameters.p = 0.087) and placebo group (p = 0.71) were reported. Moreover, a comparison of the changes between the placebo vs. soy group did not find any statistically significant differences in Ki-67 labelling (p = 0.21). There were no statistically significant differences between the treatment groups with regard to patient or tumour characteristics, including ER status of the tumours. However, a paired analysis of breast cancer-related gene expression levels was performed in pre- and post-treatment samples of small subgroups . Two genes were reported to be up-regulated in the soy group (p < 0.05), thus suggesting a treatment-related effect: FANCC, encoding a DNA repair protein, and UGT2A1, encoding a phase II metabolising enzyme involved in E2 metabolism as well as in the detoxification of xenobiotics, e.g., polycyclic aromatic hydrocarbons. It has been suggested that both genes may have a potential impact on breast cancer biology; however, the consequences of their increased expression with regard to human breast cancer remain unclear. Furthermore, differential gene expression was examined as a function of plasma genistein concentrations (high genistein: > 16 ng/mL vs. low genistein: < 6.8 ng/mL) by microarray analysis of tumour samples . High genistein plasma concentrations were associated with a change in a signature consisting of 126 differentially expressed genes, which was characterized by the overexpression of genes driving cell cycle and proliferation pathways   and women with a high risk of developing breast cancern = 29) daily ingested a soy tablet containing 50 mg isoflavones for 12 months (n = 46) or placebo (n = 49)  to evaluate the association of isoflavone intake with breast cancer risk. They allow investigating breast cancer as a primary endpoint instead of surrogate markers or intermittent endpoints used in RCTs. They also usually include a higher number of participants than a RCT and, therefore, have the power to detect weaker associations, which refer to the entire population. Furthermore, if compared to RCTs, data from a prolonged period of exposure can be considered in observational studies. However, in contrast to RCTs, observational studies cannot unequivocally prove causality; they merely report associations between an exposure and the respective endpoint. In addition, observational studies are prone to the possibility of confounding. Therefore, appropriate exposure assessment and statistical analyses to control for these biases are crucial. Specifically, an association of other risk factors for breast cancer such as age, BMI (body mass index), smoking status and alcohol consumption with soy consumption has to be taken into account if present.To identify associations between nutritional exposure and cancer risk, different designs of observational studies have been used: (i) prospective cohort studies; (ii) retrospective case-control studies, and (iii) nested case-control studies, in which incident cases in a prospective cohort are compared with selected controls of the cohort. The results of these studies can be influenced by biases, which might be restricted to or be more pronounced in a specific study type. For example, the selection bias might exert an influence especially on retrospective case-control studies. One possible source of this bias is that the control group might differ from the case group regarding characteristics that are beyond exposure but also influence the breast cancer risk, e.g., a greater proportion of health conscious and consequently healthier participants in the control group. A specific limitation, also a type of selection bias, might occur in cohort studies if study participants are not available for a follow up. The ‘loss’ of study participants could distort the results, in particular if the participants and non-participants differ regarding specific study-relevant characteristics.In retrospective case-control studies, exposure assessment is based on a subjective recollection that might be biased by the disease  and thus can differ between healthy controls and cancer patients. In addition, misclassification can occur in both retro- and prospective studies, for example if the mean daily intake of soy, soy proteins or isoflavones is derived from dietary assessment methods, like food frequency questionnaires (FFQ), which is the case in most of the discussed studies. This may be stated as non-differential misclassification, i.e., this will dilute the real exposure-outcome relationship. Overall, based on the described limitations, the Centre for Evidence Based Medicine  considers the strength of evidence provided by prospective cohorts to be higher than that of retrospective case-control studies. However, the final weight of a study not only depends on the study type, but also on an adequate control of biases.Notably, many meta-analyses published up to now do not take into account the differing study designs of the individual studies when drawing overall conclusions. It is, therefore, important to examine in a meta-analysis whether the concluding results are different in prospective and retrospective case-control studies. If the observations from retrospective case-control studies cannot be confirmed by prospective studies in a comparable study population, the overall results of the meta-analysis should be interpreted with caution.In addition, the meta-analyses are potentially biased when they combine results from Asian and Western study populations, because these populations markedly differ regarding their daily soy food consumption and the duration of exposure as well as other risk factor patterns. Chinese and Japanese populations show the highest isoflavone intakes worldwide. Their daily intake ranges from 16 to 70 mg/day see “”. In conIt is just as important that observational studies are properly designed, i.e., (i) the scientific question (based on comprehensible hypotheses), observed endpoints, target population and needed participant number must be defined a priori; (ii) correct and harmonised investigational instruments  must be used, and (iii) adequate statistical analyses must be conducted.Isoflavone intake and breast cancer incidenceEvaluation of meta-analyses Since 2006, seven meta-analyses and one systematic review examined the association between the dietary intake of isoflavones or soy proteins and the incidence of breast cancer in humans. They often included data of study populations differing in various characteristics, such as geographic area or menopausal status. In many cases, the statistical analyses were conducted on a subgroup of the included studies to answer specific questions. Because of this, the conclusions drawn by the meta-analyses were probably based on a subgroup of the total number of study participants, and declaring the total number of participants is only reasonable if the size of the respective subgroup is also specified.As previously discussed, meta-analyses and systematic reviews that combine all study types and/or combine both Western and Asian populations should be interpreted with caution. The meta-analyses conducted with studies on Western populations did not demonstrate a statistically significant (neither positive nor negative) association with isoflavone intake, except for the beneficial effect described in the study by Chen et al. ; Table 4p = 0.31). In contrast, a significant difference  was reported in postmenopausal Asian women. Thirteen case-control studies showed a strong inverse association  and five cohort studies did not   when compared to retrospective case-control studies (ranging from 0.50 to 0.83). However, adverse effects were never described. Since most of the meta-analyses did not stratify regarding the study population (Western/Asian) and study type (prospective/retrospective), these results should be interpreted with caution for a final evaluation of the risk.Evaluation of the prospective cohort studies To convincingly exclude the occurrence of adverse effects due to isoflavone intake on breast cancer incidence in observational studies, the data of the prospective studies in the discussed meta-analyses  and 3,3′,5-triiodo-l-thyronine (T3). T4 is converted to T3 by type 1 and type 2 iodothyronine deiodinases  of the selenoenzyme family . TSH induces an increase of the thyroid hormone concentration in blood by, e.g., mediating the uptake of iodide into follicular cells of the thyroid gland via the sodium/iodide symporter (NIS) Fig. , no. 1 . The funily Fig. . Some prily Fig. . Althougily Fig. . Thyroidily Fig. , T3 was ily Fig. . Besides50) of TPO of porcine origin is already reached at a genistein and daidzein concentration of approx. 1–10 µM  in serum and CSF  and TSH levels in humans see “”.r = 0.33, p = 0.03) and between T3 and total serum isoflavones ]. This increase in T3 was also associated with an increase in the progesterone levels (p < 0.01). In a second phase, half of the animals of each group were ovariectomised and continued to consume their pre-ovariectomy feed for another 34 months. The blood samples taken 9 months after ovariectomy revealed that soy in contrast to the casein-lactalbumin treatment in the first phase before ovariectomy prevented the decline in T4 after surgical menopause  factors. To evaluate the functioning of the thyroid hormone system in the clinic, biomarkers are used, whereby their physiological relevance is not yet entirely clear. Normally, the initial screening consists of measuring the TSH level in blood. If this parameter is elevated, free T4 concentrations are analysed to confirm the diagnosis of hypothyroidism  reports on soy-induced goitre in babies and infants given soy milk instead of cow milk contributed to the mandatory iodination of baby and infant formulas Hydovitz . The impImportantly, human observational and interventional studies indicate that consumption of soy-based foods is unlikely to have an adverse effect on the thyroid gland system in healthy humans, if the iodine intake is adequate  such as perchlorate  and fT4 levels decreased by 25% . The urinary iodine excretion did not differ significantly between patients that developed overt hypothyroidism and the rest of the study population . Forty-eight participants completed the study. Within this subcohort, a difference concerning the mean TSH, fT4 and fT3 concentrations between the two intervention groups was not observed . An improvement of the high blood pressure, insulin resistance and the C-reactive protein level (an inflammation and arteriosclerosis marker) was reported.A randomised, double-blind, crossover study in patients with subclinical hypothyroidism and adequate iodine intake investigated the effect of isoflavone supplements on the thyroid status by measuring urinary iodine excretion  hypothyroidism. In a case-report of a woman with hypothyroidism after a near-total thyroidectomy, the need for higher oral doses of levothyroxine to reach therapeutic serum thyroid hormone concentrations was observed. It was reported that this was caused by the administration of levothyroxine concomitantly with a dietary supplement on soy protein basis that resulted in a decreased absorption of levothyroxine  or with non-soy formula (n = 70). Because of the study design, differences in treatment regimens and timing of sampling between the groups hampered the comparison of some values between the groups. The authors observed that patients of the soy diet group had a prolonged increase of the TSH levels when compared to the non-soy diet group. The median to achieve normal TSH concentrations of < 10 mU/L was 150 days (54–229 days) when compared to 40 days   were published  the study participants consumed approx. 120 g (2 g/kg bw) of unprocessed boiled natural soybeans (Alfa Bio Slovakia) containing 1.2–4.2 mg of isoflavones per g  from the Czech Republic, Milerova et al.  analysedZung et al.  describeA randomised, double-blind study performed in the UK investigated the effects of soy in men with type 2 diabetes mellitus and subclinical hypogonadism  level, which shows a similar mode of action as TSH, strongly increases in the first trimester. (Temporary) subclinical hypothyroidism is a relevant issue during pregnancy. A screening revealed that 3–10% of pregnant women suffered from subclinical hypothyroidism  as yet did not indicate adverse effects of isoflavone intake on thyroid parameters. Only one study  reported an effect of the isoflavone intake on clinical parameters. Whether this effect is physiologically relevant needs to be clarified.Whether isoflavone intake influences the development or progression of thyroid cancer is still under discussion. In this context, only a small number of studies investigating a potential carcinogenic mode of action of isoflavones has been published so far. Yin et al.  showed t2O2/free radicals or indirectly by increasing the number of cell divisions  is generally agreed. However, findings in experimental animals due to isoflavone exposure cannot a priori be extrapolated to the situation in humans. The assessment of the results from animal studies should consider existing limitations of each animal model see “” especiaRCTs in general are the most suitable study type in evidence-based research, because they are able to show causal relationships. However, the available RCTs investigating the influence of isoflavones on breast cancer risk exhibit some limitations. The data from various studies are difficult to compare due to large differences regarding the study design and a rather low overall number of study participants see “”. FurtheObservational studies are a valuable tool to evaluate the influence of isoflavone intake on breast cancer risk, since breast cancer can be investigated as a primary endpoint in comparatively large study populations. However, they merely report associations and not causal relationships. In addition, they might enclose biases in various directions and other distortive effects, which might increase the general uncertainties of the results. Furthermore, the available meta-analyses on observational studies have considerable limitations see “”. TherefThe influence of isoflavones on an existing breast tumour might differ considerably from that on breast tissue in healthy women. Breast cancer patients and women with undetected breast cancer are considered as particular risk groups, and data from these groups are regarded to be of special relevance for risk assessment. However, the available data are rather limited and further studies are needed see “”.In Asian countries it is assumed that the isoflavone intake mainly results from a lifelong consumption of soy food already starting early in life. It has been suggested that isoflavones may exert their potentially protective effects early in life by stimulating breast cell differentiation. Several animal studies appear to support this hypothesis see “”, but thSome studies indicate that the time of exposure to isoflavones may play a pivotal role when assessing effects of estrogenic compounds on the female breast see “”. It hasPotential anti-thyroid effects of isoflavones are considered to depend on the iodine status of the study participants. In this context, it should be mentioned that iodine deficiency is still a worldwide problem including Western populations see “”. TakingOnly a limited number of studies are available. Many of the studies show a deficient study design . Some studies lack information on whether participants suffered from any thyroid dysfunction  at the beginning of the trial, which could have influenced the outcome of the studies see “”.Blood TSH or free T4 levels are used in the clinic to evaluate thyroid gland function see “”. These An effect of isoflavones on the thyroid hormone system most likely could be expected in certain risk groups, which include persons with an iodine deficiency, a  and congenital hypothyroidism as well as pregnant women due to the enhanced metabolic requirements of the thyroid system during pregnancy and the high sensitivity of the foetus to an impaired thyroid function. Postmenopausal as well as ovariectomised women are also regarded as potential risk groups, especially if their iodine supply is not adequate, since the incidence of  hypothyroidism increases with age. It has to be noted that there might be additional risk groups, e.g., men with type 2 diabetes mellitus and subclinical hypogonadism see “”.in vitro and animal studies are outlined below.Conclusions arising from the re-evaluation of health effects of isoflavones in humans based on an analysis of interventional and observational human studies as well as experimental Data from in vitro studies and animal experiments suggest that the estrogenic as well as the anti-estrogenic effects mediated by isoflavones are mechanistically plausible. Animal studies on the potential influence of isoflavones on tumour induction did not show significant differences in the incidence of adverse effects. Some studies found indications for preventive effects, especially in the case of a prepubertal exposure to isoflavones. In several studies addressing a potential promoting activity on the growth of already existing ER-positive mammary tumours, tumour cell growth was stimulated. However, in other studies, no such adverse effects were observed. The outcome strongly depends on the isoflavone tested, the study design as well as the animal models used. The relevance of the used animal models to understand the situation in humans remains unclear at the present time due to limitations of these models and species differences.Isoflavones  did not affect the breast density and the expression of proliferation markers in breast tissue samples of healthy postmenopausal women, while marginal adverse effects on these parameters were reported for healthy premenopausal women. Again, the relevance of these markers remains uncertain at the present time.In one pilot study the effect of isoflavone exposure on different parameters in pre- and early postmenopausal women with invasive breast cancer scheduled for resection were analysed. The expression of Ki-67 and the apoptosis marker caspase-3 was not affected by isoflavones , whereas the expression of a number of breast cancer-related genes was altered when compared to the placebo group. Further studies are needed to verify these pilot results and to determine whether these effects are time- and dose-dependent.Further intervention studies analysed various other endpoints, e.g., the volume of the nipple aspirate fluid (NAF), the expression level of growth factors or markers of oxidative stress and inflammation/immune response. Some of these endpoints have been suggested to be related to breast cancer risk, although their relevance is not yet clear. The evidence from these studies is, therefore, considered inconclusive.The data, albeit not consistent regarding a potential risk reduction, appear to exclude an adverse effect of the exposure to dietary isoflavones on breast cancer incidence at the investigated intake levels (up to approximately 70 mg). In a few Asian study populations exposed to higher levels of dietary isoflavones than Western populations, in which soy intake is usually low, a significant breast cancer risk reduction was reported, predominantly in postmenopausal women. In most of the meta-analyses, this protective effect was mainly observed in retrospective case-control studies and was not confirmed by the available prospective studies. Thus, these effects may reflect a selection and information bias introduced by the retrospective case-control study design.The very few data investigating the impact of isoflavone intake on breast cancer recurrence reported a protective effect in Asian as well as in Western populations. Only a few observational studies addressed the association between isoflavone intake via dietary supplements and breast cancer risk and no evidence of an association was found. Studies examining the influence of the equol producer status on breast cancer incidence are limited in number and inconclusive up to now.Various in vitro and animal studies reported that isoflavones are able to interfere with different checkpoints of the hypothalamic/pituitary/thyroid system. An influence on clinical markers for thyroid function such as TSH, fT4 and fT3 was also reported in several studies. Whether these effects might be relevant under realistic exposure conditions in humans is still unclear.The non-risk groups include healthy, non-pregnant, premenopausal women with an adequate iodine status. Isoflavones did not lead to functional alterations in the thyroid hormone system of this population group. A study on hypercholesterolemic children did not reveal alterations of thyroid hormone blood parameters/biomarkers  due to isoflavone intake.The population groups in which isoflavones might influence the thyroid hormone system include individuals suffering from iodine deficiency and  hypothyroidism, which is especially relevant for the group of postmenopausal and ovariectomised women. The few available (and limited) studies in patients with an impaired function of the thyroid gland, i.e., with  hypothyroidism, indicate that isoflavones might exert a negative effect on the thyroid hormone system. In some studies with postmenopausal or ovariectomised women, slight alterations of the thyroid hormone blood parameters  following isoflavone intake were observed. These effects need further research to clarify their reversibility and physiological relevance. It has to be pointed out that the studies on postmenopausal or ovariectomised women showed limitations in their study design . In addition, pregnant women must be considered as a risk group. In the only study with pregnant women, no adverse effects due to the consumption of soy foods were reported. Studies in further potential risk groups are scarce. An RCT with men suffering from type 2 diabetes mellitus and subclinical hypogonadism reported an association between the intake of an isoflavone-containing snack and a significant increase of the TSH concentration in blood, whereas fT3 was not affected.The influence of isoflavone intake on thyroid cancer risk has not yet been adequately analysed in observational studies and the evidence is inconclusive.The available human studies do not indicate that an isoflavone exposure as reported in the thoroughly studied Asian population or as investigated in clinical studies  negatively influences breast cancer risk or the thyroid hormone system in healthy women. However, the SKLM points out that particular attention should be given to the susceptible risk groups. These include people with an iodine deficiencyAs a measure of precaution, the SKLM recommends such risk groups to abstain from the intake of isoflavone-containing supplements. As a pragmatic guidance for these groups, the SKLM also recommends the dietary intake of isoflavones through consumption of soy foods not to exceed the median intake in Asian countries of around 50 mg/day considered as safe.There is a need for further scientific research to be able to perform a conclusive risk assessment on the impact of isoflavones on breast tissue and the thyroid hormone system. In particular, the following topics should be addressed:uptake of isoflavones and metabolites as well as isoflavone and metabolite profile in target tissues, also addressing species-specific differenceseffects of isoflavone aglycones and conjugated forms on the membrane estrogen receptor GPEReffects of isoflavone metabolites  in target tissuesimpact of the microbiota on the bioavailability of isoflavonesdevelopment of adequate biomarkers for increased breast cancer riskphysiologically based biokinetic (PBBK) models to predict in vivo dose–response curves for estrogenic activity in target tissues or modulation of the hypothalamic/pituitary thyroid system in humansimpact of isoflavones on the female breast tissue in pre- and postmenopausal women investigated in RCTs with a standardised and validated study design/protocolimpact of isoflavones on breast cancer recurrencesystematic identification of GPER in breast cancer diagnosisassociation between isoflavone intake via supplements and breast cancer riskinfluence of isoflavones in mediating goitrogenic effects, particularly in risk groups  and analysis of the underlying mechanismsintegration/application of -omics technologies, especially metabolomics in further studiesBelow is the link to the electronic supplementary material.Supplementary material 1 (DOCX 370 KB)


Some studies have investigated the effects of iron on breast carcinogenesis and reported different findings about the association between Fe and breast cancer risk. This study was conducted to estimate this effect using meta-analysis method.A total of 20 articles published between 1984 and 2017 worldwide were selected through searching PubMed, Scopus, Embase, Web of Science, and Cochrane Library. Keywords such Breast Cancer, Neoplasm, Trace elements, Iron, Breast tissue concentration, Plasma concentration, Scalp hair concentration, toenail concentration and their combination were used in the search.The total number of participants was 4,110 individuals comprising 1,624 patients with breast cancer and 2,486 healthy subjects. Fe concentration was measured in the various subgroups in both case and control groups. There were significant correlations between Fe concentration and breast cancer in breast tissue subgroup . Whereas, there was no meaningful difference in Fe status between women with and without breast cancer related to scalp hair and plasma subgroups; (SMD: -3.74  and (SMD:-1.14, respectively.The present meta-analysis indicated a positive and straight association between iron concentrations and risk of breast cancer but because of high heterogeneity we recommend more accurate future studies. Breast cancer has the most cancer incidence in women and also the second most common global cancer , 2. It rThese elements can be essential and benefit in small concentrations or toxic and carcinogenic, when taken in excess . ResearcOne of them is Fe- in carcinogenesis of breast cancer. Iron works as a structural and functional cofactor for various proteins and enzymes, a prosthetic group in many enzymes and an important constituent of succinate dehydrogenase as well as a part of the hem of hemoglobin, myoglobin, and the cytochromes , 17. It There are many studies with different findings concerning the influence of Fe in the incidence of breast cancer; and lack of systematic review and meta-analysis in this area to provide an overall and valid result, conducting a meta-analysis is important; because a meta-analysis study leads to a large sample size and overall resolution. The aim of this study was to investigate the influence of Fe on breast cancer by reviewing the available studies.Study selection: We performed a literature search with citations in the Scopus, PubMed, Web of Science, Embase, and Cochrane Library databases for case-control and cross sectional published between 1984 and 2017. The search strategy was done via keywords: Breast Cancer, Trace elements, Iron, Breast tissue concentration, Plasma concentration, Scalp hair concentration, toenail concentration and their combination. The search scope was developed using the wildcard symbol ‘*’ and an advanced search was performed with the combination of words or phrases using Boolean operators . The titles from searching were scanned to be appropriated for inclusion in the study. Furthermore, the lists of reference from all related reviews and main articles were manually searched for more references. Inclusion and exclusion criteria: All studies that analyzed Fe levels in breast Cancer patients were reviewed. Each screened study for inclusion in final analysis must present the data on the relation between Fe levels and breast cancer risk by measuring this element concentration in any of three types of sample specimens: serum, breast tissue and hair. Study was limited to conduct articles in humans. We excluded studies if they were duplicate publications or that were meta-analyses or systematic considerations; if they perform on non-human creatures ; if they presented insufficient data; and if published in languages other than English. We searched gray literature as far as possible in search engineers, but access to all of the gray literature sours was not possible. Data extraction: The extracted data for all studies  include the first author, year of publication, sample size, sample age, location, iron concentration, mean difference, type of sample specimens, and iron screening method (figure 1-study flowchart). Two of the authors independently extracted information from each article and compared findings. In which cases, the results were discordant, papers were reviewed jointly and discrepancies between researchers were resolved via group discussions. Evaluation of the quality of selected studies: In this study, Newcastle–Ottawa Scale checklist was used to assess the quality of studies  was used for statistical analyses.In initial search process, 71 studies were identified. Of these studies, 9 duplicates were excluded. We excluded other 42 articles . After detailed review of selected articles, 20 published studies between 1984 and 2018 including four cross-sectional  and 17 c2=98.0%; P=0.000]  was measured in analysis. Among the included studies, two of them were excluded from analysis because they did not report the iron concentration in control group , 37. AlsP=0.000] . We condP=0.000] . This study systematically reviewed the effects of iron in breast cancer and quantitatively analyze the association between iron levels and the risk of breast cancer. The current review including 20 studies , showed The present study via meta-analysis method proved a direct relationship between high iron levels and greater risk of breast cancer. Similarly, a systematic review summarized the evidence regarding the relationship between Fe and breast cancer risk and concluded that this trace element can apply a stimulatory function in breast cancer . Accordi2+ + H2O2 Fe3+ + OH + OH –Iron is necessary for physiological cellular functions because it is an inseparable part of many proteins and enzymes . It fundThese reactions produce hydroxyl radicals that lead to lipid peroxidation, DNA damage, inactivate enzymes, and depolymerize polysaccharides and apoptosis -51. In bIron as a nutritious substance participates in the feeding of microbial and neoplastic cells and thereby leading to disease progress . Iron alWe conducted subgroup analysis based on the type of sample specimens to address the observed heterogeneity, and we could not find a meaningful association between iron levels in serum and scalp hair with breast cancer, whereas our analysis revealed a significant relationship between high levels of iron and greater risk of breast cancer in breast tissue and also a relatively mild association in benign breast tissue. One possible reason for this observation is that excessive accumulation of free iron in benign breast tissue due to their catalytic effects can generate mutagenic radicals, and also can repress host defense cells and, thus enhances the risk of breast cancer .One of the other possible reasons is that both benign and cancerous cells may request enhanced concentration of iron for maintaining their proliferation due to iron is essential for ribonucleotide reductase which is a main enzyme in DNA synthesis . TherefoWe also conducted subgroup analysis based on geographic region; analysis of the association Fe statuses with breast cancer based on continent showed a significantly difference in Fe concentration between breast cancer and healthy women in Asia, Europe and Africa (p<0.05); while, no meaningful difference was found in Fe concentration between women with and without breast cancer in America (P>0.05). In Asia, low levels of Fe and in Europe and Africa high levels of Fe had positive association with the risk of breast cancer. Geographical and residential socioeconomic inequalities may potentially reflect the observed differences. Also, demographic characteristics and genetic background of different populations can also explain the observed heterogeneity. In addition, our analysis based on the quality score showed a meaningful correlation between Fe statuses and breast cancer risk only in high quality studies that this may also affect the results of heterogeneity.It has been hypothesized that dietary iron intake was positively associated with an increased breast cancer risk and several studies were performed in this regard; some of them found null results -65. WherThis meta-analysis had several limitations that most of them were related to methodology. Some of these limitations include:1. Absence of the same method for measuring variance.2. Absence of data relation to habits and lifestyle of the population studied.4. The screening methods varied and there was not a uniform standard method for measuring iron concentrations in different studies.5. Some relevant articles were not available In conclusion the present meta-analysis indicated a positive and straight association between iron concentration and risk of breast cancer (P=0.009). But because of high heterogeneity we recommend more accurate future studies.Thus, Fe levels should be controlled in food sources, drugs, and etc. This study showed that the estimation of iron concentration in biological specimens has an important role in early detection of this disease. Our results also can be considered for debarment of breast cancer by controlling level of iron in the persons' diet. There are no benefits in any form that have been or will be received from a commercial party related directly or indirectly to the subject of this article.


The purpose of this consensus guideline is to outline recommendations for genetic testing that medical professionals can use to assess hereditary risk for breast cancer.Literature review included large datasets, basic and clinical science publications, and recent updated national guidelines. Genetic testing to assess hereditary risk of cancer is a complex, broad, and dynamic area of medical research. The dominant focus of this guideline is limited in scope to breast cancer.There is a lack of consensus among experts regarding which genes among many should be tested in different clinical scenarios. There is also variation in the degree of consensus regarding the understanding of risk and appropriate clinical management of mutations in many genes.Genetic testing should be made available to all patients with a personal history of breast cancer. Recent data are reviewed that support genetic testing being offered to each patient with breast cancer . If genetic testing is performed, such testing should include BRCA1/BRCA2 and PALB2, with other genes as appropriate for the clinical scenario and family history. For patients with newly diagnosed breast cancer, identification of a mutation may impact local treatment recommendations. Patients who had genetic testing previously may benefit from updated testing. Genetic testing should be made available to patients without a history of breast cancer who meet National Comprehensive Cancer Network guidelines. Finally, variants of uncertain significance are not clinically actionable and these patients should be managed based on their individual risk factors. The American Society of Breast Surgeons recently reviewed the use of genetic testing for patients with breast cancer. An expert panel from a variety of backgrounds reviewed the current literature related to genetic testing and produced an updated consensus statement that the board of directors approved. This is now the official updated position statement of the American Society of Breast Surgeons Table . Our leaBRCA 1/2 mutations. The initial threshold for testing was set high because at that time genetic testing was very expensive and was just beginning to be used for medical care. The cost of testing has dropped dramatically (panel genetic testing can cost less than a diagnostic mammogram with an ultrasound), and the benefit to the patient and the patient’s family can be lifesaving. Unfortunately, we still see evidence that the guidelines deny patients’ access to this important testing and the valuable information it provides. Put simply, the guidelines have become more about exclusion than inclusion. This consensus statement reviews the available literature although not an exhausted systematic review, a comprehensive review of the most impactful evidence in modern literature on the subject. These guidelines now supersede similar guidelines from our society put forward in 2006, 2012, 2016, and 2017. Based on the most compelling available data to review, five clearly articulated recommendations are made for members of our society and patients with breast cancer.National guidelines were originally established to help identify patients who had a high likelihood of benefiting from genetic testing that looked only for BRCA1 and BRCA2 genes.BRCA1 or 2 mutations may not be identified.The National Cancer Institute estimates for 2018 were that more than 266,000 new cases of invasive breast cancer would be diagnosed in the United States, and more than 40,000 patients would die from the disease.There are fewer barriers to genetic testing now than previously, and testing is less costly and being offered by more labs. The indications for who should be offered testing are ever increasing—each guideline update casting a wider net, and there is more public awareness. However, some barriers remain—one of which is the limited availability of genetic counseling nationwide for patients and their family members.22Increased access to testing would likely lead to more patients pursuing testing and improving rates of identification of gene carriers. Breast surgeons are well positioned to be a resource for patients who may benefit from testing. Breast surgeons can identify individuals who are suitable for testing, inform patients of the risks and benefits, provide access to genetic testing, and also discuss risk management strategies for those patients who test positive. For patients with less common mutations, strong consideration should be given to consultation with cancer genetics specialists.25BRCA 1&2, PALB2, and other hereditary breast cancer syndromes, which include but are not limited to Li-Fraumeni syndrome (TP53 pathogenic variant), Cowden syndrome (PTEN pathogenic variant), hereditary diffuse gastric cancer syndrome (CDH1 pathogenic variant), and Peutz-Jegher syndrome (STK11 pathogenic variant).Hereditary mutations to be considered include BRCA1 pathogenic variant provides that patient the opportunity to learn of her elevated risk for contralateral breast cancer as well as of ovarian cancer and to make educated decisions to reduce those risks.TP53 pathogenic variants (associated with Li-Fraumeni Syndrome) due to their increased risk of developing radiation-induced secondary malignancies.Identification of patients with pathogenic variants in these genes can influence patient management in terms of high-risk screening and risk reduction as well as therapeutic options related to surgery, radiation, and systemic therapies.Identifying a patient who has a pathogenic variant that indicates high hereditary breast cancer risk can have a profound impact on that patient’s health and management. Additionally, it has potential impact on that patient’s family members who should be counselled to consider testing for the mutation identified in the family, the result of which can guide their risk of breast cancer development and consideration of risk management strategies.BRCA1, BRCA 2, PTEN, and TP53. Consideration may also be appropriate for patients with mutations in other genes when combined with a significant family history of breast cancer.Just because a hereditary pathogenic mutation that predisposes to breast cancer is identified does not mean that the risk-reducing mastectomy is indicated. Risk-reducing mastectomy can be considered in BRCA1 or BRCA2 pathogenic variants should consider risk-reducing bilateral salpingo-oophorectomy after child-bearing or between the ages of 35–40 years to reduce ovarian and fallopian tube cancer risk. Women with BRCA1 should consider oophorectomy between ages 35–40 years, whereas BRCA2 carriers should consider it between ages 40–45 years.Patients with BRCA2 pathogenic variants also has been shown to reduce the risk of breast cancer by approximately 50%. There also is breast cancer risk reduction from RRSO in BRCA1 patients but to a lesser degree.17Prophylactic oophorectomy in premenopausal women with ATM, CDH1, CHEK2, NBN, NF1, PALB2, and STK11, enhanced screening is recommended; however, currently the data are not sufficient to support risk-reducing mastectomy in the absence of other factors such as a strong family history. There are substantial gaps in our ability to predict individual risks associated with mutations in some of these genes. Risk is modulated by age, family history, and in some cases, the specific mutation in a particular gene. For the aforementioned syndromes, the guidelines broadly support considering mammography with tomosynthesis and breast MRI with and without contrast for annual screening due to the elevated risk for breast cancer.For patients with mutations in BARD1, MSH2, MLH1, MSH6, PMS2, EPCAM, BRIP1, RAD51C, and RAD51D, there are some data, suggesting an elevated lifetime risk of breast cancer; however, there is insufficient evidence to support change in breast cancer risk management based on the presence of a mutation alone. Mutations in these genes may be associated with an increased risk of gynecological cancers, which may warrant specific management. MSH2, MLH1, MSH6, and PMS2 are associated with the Lynch Syndrome, a multiorgan predisposition syndrome that requires multidisciplinary management.For www.nccn.org under the title Familial High-Risk Assessment: Breast and Ovarian Cancer (most recently updated in early 2019). The All Syndromes Known to Man Evaluator (https://ask2me.org/) is another tool available with information on the spectrum and estimated penetrance for pathologic variants.29The list of actionable genes and recommendations for screening and risk management continually evolves as additional information becomes available. We refer the readers to the NCCN guidelines, available online at Health care providers and patients need to know that genetic testing is one of several tools for assessing breast cancer risk. Not every genetic test yields a straightforward answer with clear guidance on how to proceed for optimal care. Patients should be made aware that negative test results do not necessarily mean they are not at increased risk for developing breast cancer.CHEK2 and ATM variants have low penetrance, whereas other types are more highly penetrant.http://brcatool.stanford.edu/brca.html, can be useful in known BRCA pathogenic variant carriers to predict likelihood of developing breast or ovarian cancer and likelihood of dying from either disease based on patient age and a variety of interventions chosen for screening and prophylaxis. It is important to note that these calculators are constrained by the limitations of the studies that provide the underlying odds ratios used to generate the absolute risk estimates and do not account for modification of those odds ratios by age, mutation position, family history, or polygenic background risk.34Many factors contribute to a patient’s lifetime risk of breast cancer, and genetic testing is an effort to better define one of these elements (the measurable inherited risk). When counseling patients about their lifetime risk of breast cancer, it is critical to look at the patients’ other contributing factors, such as age, medical history, lifestyle, exposures, and family history. For patients who test positive for a pathogenic variant, it is important to gain detailed understanding of that variant when advising on risk management strategies—details, such as the penetrance of the cancer risk among carriers . Penetrance varies among the identified hereditary cancer syndromes. Not all carriers of pathogenic genetic variants will develop breast cancer, and the level of risk varies with the gene affected and likely the variant as well.Before testing, patients need to be made aware of the implications that the test result can have (pre-test counseling); and when results become available, patients should be reminded of these implications and be provided the appropriate clinical context for the results to make informed decisions (post-test counseling). All genetic testing should be performed in the setting of informed consent. The American College of Surgeons Commission on Cancer accreditation program mandates that cancer risk assessment, counseling, and genetic testing services be provided to patients by a physician who does risk assessment regularly and/or is qualified to do testing or a qualified genetic professional either on site or by referral.Post-test counseling is important regardless of the actual result. The current best practice is for all patients who undergo genetic testing to have some form of post-test counseling. By NCCN guidelines, this can occur in person or remotely. This allows for patients’ questions to be answered and for a thorough debriefing. If a result is negative or noninformative (such as a variant of uncertain significance [VUS]), then the patient’s other risk factors for breast cancer  need to be evaluated to formulate the appropriate risk management plan. Depending on the level of risk for breast cancer, strategies to manage that risk can be discussed, including enhanced screening imaging ; chemoprevention (endocrine therapy to lower risk); lifestyle modification with respect to obesity, tobacco use, and alcohol consumption; and exogenous hormone use among others.For patients who test positive for a pathogenic variant, a clear review of the state of evidence for that specific syndrome is imperative. To make educated decisions, patients need to know about the spectrum of risk management strategies. Ultimately, a customized plan for the patient is the goal with their informed consent. In this discussion, a frank statement of the level of risk reduction for each intervention is needed. For example, risk-reducing mastectomy and reconstruction in a BRCA1-positive 35-year-old patient leads to much greater risk reduction for breast cancer mortality than that same intervention in a 65-year-old patient.BRCA1 and BRCA2 remain the most likely genes to be mutated in a family with high breast and ovarian cancer risk, panel testing can allow for more comprehensive coverage of less common syndromes that can also confer hereditary cancer risk.BRCA1 and BRCA2) being in PALB2, CHEK2, and ATM.BRCA1 and BRCA2. However, the presence of mutations in PALB2, ATM, truncating mutations in CHEK2, and possibly other genes are likely to be associated with lifetime breast cancer risks of greater than 20% and therefore, in the United States, at least support a decision for enhanced surveillance with annual mammography with tomosynthesis and breast MRI with contrast. Mutations in other genes also may reach this threshold, although the rarity of such mutations and the possibility of subtype-specific predisposition make risk estimation more challenging. A multigene panel may include genes with varying degrees of evidentiary support and “actionability.” This testing method is optimal when the individual genes included are clinically valid and comprehensively address the details of each patient’s case.Genetic testing has expanded in scope and availability since 2013 when the U.S. Supreme Court ruling in Association for Molecular Pathology v. Myriad Genetics, Inc. increased the testing options. Increased competition has helped to lower the cost. Improvements in technology, such as next-generation sequencing, has made testing for more than one gene at a time a reality, which can improve the cost-effectiveness and efficiency of testing.BRCA pathogenic variants first, then selecting additional genes if BRCA tests are negative).20,30,43 Surgeons, genetic counselors, and other health care professionals who order panel testing for breast cancer patients or their family members should at a minimum test the breast cancer genes that are clinically actionable given the current state of medical evidence. Testing of additional genes can be performed at the discretion of the ordering physician or as directed by the family history.Panel testing can be considered for patients who qualify for hereditary breast cancer testing to more efficiently and cost-effectively evaluate genes that confer risk and impact management recommendations. When genetic testing is being recommended based on phenotypic syndromes , then multigene panel testing is likely to be more efficient in evaluating patients. In fact, the most recent NCCN guidelines allow that panel testing will largely replace sequential gene sequencing , ClinVar (https://www.ncbi.nlm.nih.gov/clinvar/), and NCCN (https://www.nccn.org) are available to help surgeons and other providers manage patients with hereditary conditions.While surgeons unfamiliar with hereditary cancer syndromes should not interpret the results, the number of breast surgeons trained to do this interpretation is increasing rapidly due to its growing importance in day-to-day care and our society’s concerted efforts to educate our membership. Breast surgeons understand or can learn that managing a mutation varies based on many factors, that a negative genetic testing result is of little value without proper context, and that a variant of uncertain significance is not clinically significant, among other nuances. The ASBrS provides courses at every annual meeting that cover when to order testing on affected and nonaffected patients, how to manage the results, and how to conduct proper counseling of patients and their families. Online resources such as Ask2Me.Org (As genetic testing expands, it is possible that laboratories with inadequate quality standards will appear in the marketplace. It is important to choose the lab carefully making sure they provide quality testing with accurate results and appropriate follow-up.These are guidelines, not rules, and there are patients for whom these guidelines will not apply. However, too many patients develop cancers that might have been prevented or found earlier if genetic testing had been performed. Our society has a responsibility to offer genetic testing to those interested patients in order to act when we see an opportunity to decrease unnecessary morbidity and mortality. We do so today with the adoption of our new position on this issue.


This matched cohort study investigates whether early-stage breast cancer and subsequent chemotherapy are associated with the risk of developing atrial fibrillation among women in Ontario, Canada, who were diagnosed with early-stage breast cancer compared with women without breast cancer. Are early-stage breast cancer and subsequent chemotherapy associated with a higher risk of atrial fibrillation?In a cohort study of 68 113 women diagnosed with early-stage breast cancer and 204 330 age-matched cancer-free controls, women with early-stage breast cancer developed atrial fibrillation at a significantly higher rate than that in the cancer-free controls in the first year and after 5 years following their diagnosis but not in the intervening years. The absolute incidence at 10 years was minimally but significantly higher in women with early-stage breast cancer than in the cancer-free controls (7.4% vs 6.8%); chemotherapy exposure was associated with increased risk of atrial fibrillation; however, an increased risk of atrial fibrillation was not observed with anthracyclines or trastuzumab relative to other types of chemotherapy.This study’s findings suggest that women with early-stage breast cancer may experience a marginal but significant increase in the risk of developing atrial fibrillation compared with age-matched women without cancer. Several types of cancer have been linked to a higher risk of developing atrial fibrillation (AF). Fewer data exist regarding early-stage breast cancer (EBC), for which cardio-oncology concerns are more pertinent.To investigate the association of EBC and subsequent chemotherapy with the risk of developing AF.This was a population-based, retrospective, matched cohort study conducted in Toronto, Ontario, Canada, of 68 113 women diagnosed with EBC between April 2007 and December 2016 who were matched 1:3 to a cancer-free control group based on birth year and receipt of breast imaging. Prevalence of AF before the index date (date of EBC diagnosis) was compared between the cohorts using the McNemar test. Cumulative incidence function curves were used to describe the AF incidence. To study preexisting AF, participants were matched before exclusion for prior AF. For the remaining analyses, we excluded women with prior AF before matching. An analysis was conducted beginning 1 year after the index date , which we stratified by chemotherapy exposure. Multivariable cause-specific regression was used to determine the hazard ratio (HR) associated with EBC relative to the controls and the association of chemotherapy with AF in patients with EBC.Breast cancer and chemotherapy.Incidence of AF.P = .21). At 10 years after the index date, the AF incidence was 7.4%  for women with EBC and 6.8%  for the controls (P < .001). The adjusted cause-specific HR was significantly elevated at year 1  and after year 5  but not during years 2 through 5. Analyses beginning 1 year after diagnosis showed attenuated differences that remained statistically significant: the cumulative incidence of AF at 9-year follow-up was 7.0%  for patients with EBC and 6.5%  for the cancer-free controls. The rate of AF was higher in women who received chemotherapy  but was not associated with exposure to anthracyclines or trastuzumab.A total of 68 113 women with EBC and 204 330 cancer-free controls were included in the study; both groups had a mean (SD) age of 60 (13) years. Of the women with EBC, 44.3% were diagnosed as having stage I breast cancer; 38.7%, stage II; and 13.4%, stage III; cancer stage information was missing for 3.6% of the patients. No difference was observed in preexisting AF prevalence (5.3% in the EBC cohort vs 5.2% in controls; This study’s findings suggest that patients with EBC may not have a higher prevalence of AF before cancer diagnosis. A higher rate of AF was observed in the first year and after 5 years following the EBC diagnosis. The rate of AF was higher in patients who received chemotherapy but appeared to not be associated with specific cardiotoxic agents. These findings suggest that the early and late periods of increased AF risk in EBC survivors warrant focused research to better understand the underlying causes and subsequent implications. Accordingly, a diagnosis of AF would translate to a clinically relevant stroke risk for many EBC survivors. However, there are scarce and conflicting data on the risk of AF in this increasingly prevalent group of cancer survivors.25 Generally, the treatment of EBC involves less invasive surgical procedures, and these patients are at a lower bleeding risk, making it a better population in which to investigate whether cancer or its treatments are associated independently with AF.Cardiovascular disease is a particularly pertinent clinical concern for women diagnosed with early-stage breast cancer (EBC).We designed a population-based, retrospective, matched cohort study to investigate the risk of developing AF among patients diagnosed with EBC. We hypothesized that patients with EBC may have a higher risk of AF than that for the age-matched, cancer-free control group and that the rate of AF may be higher in patients treated with cardiotoxic systemic chemotherapy. In addition, we hypothesized that patients with EBC may not have a higher prevalence of AF preceding their cancer diagnosis.27; consequently, research ethics board approval is not legally required, and informed patient consent was not needed. We used validated algorithms to identify several medical diagnoses using ICES-based data sources.35 Incidences of AF were identified using an algorithm that incorporates hospital or emergency department diagnostic codes and physician claims. The algorithm had a sensitivity of 71% and specificity of 99% when validated against electronic medical records from Ontario’s family physicians.36 This study followed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guidelines.The Ontario Health Insurance Plan provides the residents of Canada’s most populous province with universal coverage for medically necessary services. This study used several population-based administrative databases  for continuous variables and counts (with percentages) for discrete variables. The magnitudes of differences between groups were compared using weighted standardized differences because they are not influenced by large sample sizes. The proportion of patients with prior AF in the first pair of matched cohorts was compared using the McNemar test.37 was used to describe the risk of AF over time in the second pair of matched cohorts. Fine-Gray regression with adjustment for clustering within matched sets was used to test for statistically significant differences in AF incidence between patients with EBC and the cancer-free controls.38 Next, we developed a multivariable cause-specific hazard regression model, with EBC status as the key risk factor and time to AF as the outcome while accounting for matched sets. Model covariates included age, year of cohort entry, rural residence, ischemic heart disease, heart failure, diabetes, hypertension, peripheral vascular disease, stroke, chronic obstructive pulmonary disease, and chronic kidney disease. We also adjusted for the number of family physician and specialist claims  as a time-varying covariate to account for differences in health system contact. The proportional hazards assumption for EBC status was violated; therefore, we calculated the hazard ratio (HR) annually until year 5.The cumulative incidence functionAfter observing markedly higher AF rates in year 1 among patients with EBC, we generated another set of cumulative incidence function curves beginning 1 year after the index date  for living patients with EBC and their living matched controls to explore whether the AF diagnosed in year 1 was transient. This analysis was stratified based on chemotherapy exposure in the year following EBC diagnosis to study its association with the risk of AF.40: anthracycline-based chemotherapy without trastuzumab, trastuzumab without anthracyclines, anthracycline-based therapy followed by trastuzumab, and other chemotherapy without anthracyclines or trastuzumab (reference category). Both models analyzing chemotherapy exposure additionally censored women when documented with distant metastases because they may be switched to different chemotherapy regimens. We repeated both analyses in patients with EBC who were 66 years or older to additionally adjust for baseline medication use and time-varying covariates modeling endocrine therapy exposure after the index date. In a post hoc exploratory analysis, we examined the association of AF with cancer recurrence . The first date of chemotherapy served as the index date in this analysis. Chemotherapy exposure was modeled as a time-varying covariate with 4 potential categories as previously describedP < .05.Since this study used administrative data sets from a universal health care system encompassing the entire population, we assumed that missing data were negligible unless otherwise stated. Most analyses were conducted using SAS, version 9.4 (SAS Institute Inc). The matched Fine-Gray regression analyses were conducted using the crrc function from the crrSC package for R . All statistical tests were 2-sided. Statistical significance was defined as a 2-tailed P = .21).A total of 95 539 women diagnosed with breast cancer during the accrual period were considered for cohort creation. As illustrated in eFigure 1 in the After excluding women with prior AF, we identified 68 113 patients with EBC, who were matched to 204 330 cancer-free women. The baseline characteristics of this matched sample are summarized in P < .001). This translated to approximately 1 extra case for every 189 women after 10 years. The corresponding cumulative incidence of death before AF was 18.5%  for patients with EBC and 8.9%  for the cancer-free controls.During a mean (SD) follow-up of 5.7 (2.9) years, AF was observed in 3131 patients with EBC (4.6%) and 8793 cancer-free controls (4.3%). Death before AF occurred in 7519 patients with EBC (11.0%) and 10 724 cancer-free controls (5.2%). A greater number of family physician and specialist fee claims was observed for patients with EBC compared with that for the cancer-free controls, although these differences decreased over time . After stratifying the EBC cohort by chemotherapy exposure during year 1, the relative risk increase was more prominent in women who received chemotherapy. This was a younger group of patients ; thus, the incidence of AF was lower in these women and their matched controls. The risk of AF in patients with EBC who received chemotherapy was comparable with that of their matched controls in years 2 through 5, after which the curves diverged, indicating a higher risk of AF with long-term follow-up. The cumulative incidence of AF at the 9-year follow-up  was 4.7%  for patients with EBC and 4.2%  for the controls (P < .001). Among the patients with EBC who did not receive chemotherapy in year 1 , the relative risk of AF was smaller. The cumulative AF incidence at the 9-year follow-up  was 9.4%  for patients with EBC and 9.0%  for the controls (P < .001).In the analysis beginning 1 year after breast cancer diagnosis, the cumulative incidence function curves  showed aP < .001). This was comparable to the HR associated with diabetes  and hypertension . We observed similar patterns when the analysis was limited to patients 66 years or older while also adjusting for endocrine therapy as time-varying exposures and other medications at baseline.The multivariable cause-specific hazard regression model limited to patients with EBC . In the present study, we did not observe a higher risk of AF preceding the breast cancer diagnosis relative to that in matched cancer-free controls. In contrast to our findings, Wassertheil-Smoller et al20 reported an increased rate of new breast cancer diagnoses during long-term follow-up in participants with baseline AF in the Women’s Health Initiative.Numerous reports have suggested a higher risk of cancer following an AF diagnosis.15 This increased risk has been hypothesized to result from the inflammatory state associated with cancer22 or the effects of cancer treatment.23 The higher risk of AF is more commonly reported in the early period following cancer diagnosis. This may reflect postoperative AF because several studies describe this association in cancers that involve extensive surgery, such as colorectal or lung cancer.14 Fewer studies assessed AF risk during longer-term follow-up; these mostly showed smaller magnitudes of association between AF and cancer beyond the first year. An analysis of 15 428 patients from the Reasons for Geographic and Racial Differences in Stroke cohort study6 investigated the association of AF with cancer by using multivariable logistic regression after excluding patients with active cancer or cancer that was treated within 2 years of the index date. After adjustment, patients with cancer had an odds ratio of 1.19  for development of AF, which is comparable to the adjusted HR (1.20) we observed in 5-year survivors.Several studies have also reported a higher AF risk following a cancer diagnosis.12 Another study showed a 2% prevalence of AF in presurgery electrocardiograms for patients with breast cancer vs 0.6% in age-matched controls  admitted for noncancer surgery.10 A cohort study from Northern Israel reported an increased AF risk in the 90 days after breast cancer diagnosis, but not thereafter.15 D’Souza et al25 reported an increased AF rate among Danish patients with EBC from 6 months to 3 years, with an increased rate in the first 6 months only among patients younger than 60 years.There are fewer data specific to patients with EBC despite this being a clinically relevant patient group frequently treated with cardiotoxic chemotherapy. A study of 53 patients with EBC who received anthracyclines showed prolonged intra-atrial and interatrial electromechanical delay, decreased left atrial active and passive emptying volumes, and decreased atrial emptying fraction.14An important gap in these studies is that they did not specifically address chemotherapy exposure (which is more common in younger women), differences in health system contact (which introduce a detection bias), or long-term EBC survivorship. Our data indicated that patients with EBC developed AF at a higher rate than that for the matched controls with recent health system engagement despite adjustment for physician contact. This risk was higher in women exposed to chemotherapy. The comparable AF rates in years 2 through 5 and the lack of a specific association with cardiotoxic chemotherapy suggest that the higher rate in year 1 may have been mediated by temporary factors, such as hemodynamic perturbations, fluid shifts, inflammation, or other treatment-related derangements rather than treatment with cardiotoxic agents. Since the absolute risk is small, this finding does not warrant routine surveillance but rather should prompt consideration of AF in the differential diagnosis for women with compatible symptoms. Nonetheless, the implications of the early increase in AF risk should be explored further because postoperative AF following pulmonary lobectomy for lung cancer was associated with an HR of 3.75  for death among 5-year survivors.7 The etiology of this late increase in risk is unclear. Our sensitivity analysis results suggest that this increased risk may be related to cancer recurrence. Alternatively, it may be a manifestation of survival bias or the worsening cardiometabolic profile and weight gain of EBC survivors.46The late increase in AF rates among survivors treated with chemotherapy also warrants more study. Previously, we observed that EBC survivors had a higher risk of stroke without being at higher risk for ischemic heart disease. Despite the small differences in the absolute risk of AF, cancer patients may have higher rates of subsequent arterial thromboembolism.This study has limitations. Our data were limited to the Canadian province of Ontario, which may not be reflective of other parts of the world despite its ethnically diverse population. Given our reliance on administrative data, we were unable to adjust for risk factors, such as obesity and sleep apnea. We were also unable to study the association of radiation dose to the heart with the risk of AF. Our AF detection algorithm may have underestimated the absolute risk of AF because it prioritizes specificity over sensitivity. Furthermore, our adjustment for health system contact did not account for visit length and testing intensity, including the number of electrocardiograms performed. Moreover, we cannot rule out residual confounding, which may have caused us to underestimate the risk of AF after cardiotoxic chemotherapy. There was a lower prevalence of cardiovascular disease and risk factors among women exposed to cardiotoxic chemotherapy categories. Thus, our observations regarding the association between chemotherapy exposure and AF risk should be interpreted with caution. Finally, because our methods for identifying recurrent cancer have not been validated, that analysis should be considered exploratory.Our study findings suggest that a diagnosis of EBC may be associated with a small increase in the risk of AF compared with that for cancer-free women. The relative rate of AF was found to be higher for women who received chemotherapy in the first year following diagnosis. Patients with EBC who survived 5 years after diagnosis were also found to have a higher relative rate of AF, although this rate was less prominent than that in the first year. Our observations suggest that anthracycline or trastuzumab exposure may not be independently associated with a higher rate of AF compared with other forms of chemotherapy. The early and late periods of increased AF risk in EBC survivors warrant focused research to better understand the underlying causes and subsequent implications.


The median follow-up time of the subcohort was 5.3 years. Total WGR and WGW intake estimated with FFQ or reflected by total alkylresorcinol concentration in adipose tissue was not significantly associated with risk of breast cancer. However, after adjustment for total WGR and WGW intake, women in the highest quartile of relative WGR intake, reflected by the alkylresorcinol C17:0/C21:0 ratio, had a higher risk of overall breast cancer and estrogen-receptor-positive (ER+) breast cancer than women in the lowest quartile of relative WGR intake, while the risk of estrogen-receptor-negative (ER-) breast cancer incidence was unaffected. Similar results were obtained with the FFQ data. Based on these data, further investigation of the role of specific grain types in reducing or increasing breast cancer risk, and their overall impact on health, is warranted.Whole grain rye (WGR) and whole grain wheat (WGW) have been suggested to protect against the development of breast cancer. In this study, we estimated long-term intake of WGR and WGW, using both a food frequency questionnaire (FFQ) and alkylresorcinol concentrations in adipose tissue biopsies, in relation to the risk of developing invasive breast cancer in a case-cohort study ( Breast cancer is the most frequent cancer in women worldwide, with 1.68 million new cases reported in 2012 . Whole grains (WG) in the diet have been suggested to reduce the risk of developing breast cancer through the protective effects of dietary fiber and bioactive compounds ,5,6. DieAlkylresorcinols comprise a group of amphiphilic phenolic lipids mainly present in the bran part of rye and wheat among common foods in the Nordic diet ,41. WhenHowever, the relatively short half-life of alkylresorcinols in blood (~6 h) ,59 and oThe aim of this study was thus to investigate whether total whole grain rye and wheat intake and relative whole grain rye intake  are associated with breast cancer risk. Intake was estimated by FFQ or reflected by alkylresorcinols in adipose tissue and the breast cancer risk was assessed for overall, ER+, and ER- cancer, in a case-cohort study in the Danish Diet, Cancer and Health cohort. Our starting hypothesis was that total whole grain rye and wheat intake, and relative rye intake, are inversely associated with risk of breast cancer, especially ER+ breast cancer. Women from the prospective Danish “Diet, Cancer and Health” cohort study were included in the study  Figure  and the n = 74) were excluded. All invasive breast cancer cases (n = 500) were included. A subcohort of non-cases was randomly selected (n = 1148) from the cohort, of which 768 were the sub-cohort from a previous case-cohort study [Adipose tissue samples for the present study were available from a previous study  and, thert study  and 380 www.ibt.ku.dk/jesper/foodcalc). Whole grain wheat intake and whole grain rye intake in g/day at baseline were estimated by adjusting the FFQ-based intake of whole grain rye and wheat products  with their whole grain rye and wheat content reported in a previous study on 3919 randomly selected samples [Diet was assessed from a validated 192-item FFQ described in detail elsewhere ,70,71,72 samples  using a  samples , as descn = 4) per batch) were defrosted at room temperature, weighed, and mixed with alkylresorcinol internal standard mixture  and diethyl ether (1 mL) in disposable plastic vials . The plastic vials were loaded with 2.8 mm diameter stainless steel beads , placed in a Retsch MM400 tissue lyser , and homogenized at frequency 30 Hz for 2 min. The organic phase from each sample was then transferred to a new disposable plastic vial and dried at 60 °C under nitrogen for 30 min. The extract in the tube was reconstituted in methanol (1 mL) and vortexed for 30 s. The methanol-insoluble fraction of the extract was separated by centrifugation at 14,339 g for 15 min at 4 °C . The supernatant was transferred to a clean test-tube and then applied on a solid phase extraction 96-well plate  as follows: The solid phase extraction plate was conditioned with 1 mL 0.1 M NaOH in methanol ; applied with sample, and washed with 3 mL of methanol; alkylresorcinols were eluted with 2% formic acid in methanol (2 mL) and dried under a nitrogen stream at 60 °C. Dried alkylresorcinols were derivatized with 300 μL of trifluoroacetic anhydride (TFAA) at 40 °C for 60 min. Excess TFAA was removed by evaporation at 60 °C for 20 min. TFAA-derivatized alkylresorcinols were reconstituted in 30 μL undecane and analyzed using a FinniganTM Trace GC Ultra Gas chromatograph coupled to a Finnigan Trace DSQ II mass detector . The derivatized sample or reference standard in undecane solution (2 μL) was injected into a programmed temperature vaporizing injector with a steel liner at 320 °C; alkylresorcinol homologs were separated in a ZB-5MS column  with helium flow at 1.0 mL/min. The oven temperature was held at 200 °C for 2 min, raised to 310 °C for 2.2 min, and kept at 310 °C for 5 min. The transfer-line and mass detector were held at 310 °C and 250 °C, respectively. Derivatized alkylresorcinols were analyzed under electron impact ionization with selected ion monitoring at m/z 540 and 316 for C17:0, 568 and 316 for C19:0, 596 and 316 for C21:0, 624 and 316 for C23:0, 652 and 316 for C25:0. Ion m/z 316 was used for quantification of all target alkylresorcinol homologs and for quantification of internal standard homologs . Peak area ratio of C17:0/C20:0, C19:0/C20:0, C21:0/C22:0, C23:0/C22:0, and C25:0/C24:0 was calculated for all samples and converted to concentration using a 9-point standard curve constructed from solutions with different concentrations of reference compounds  and sample mass. All samples were analyzed within 18 batches. Case and non-case samples were randomly selected with a ratio of 1:2 in each batch; laboratory personnel were blinded to the case status. Intra- and inter-batch coefficient of variation (CV) for total alkylresorcinol concentration in the quality control sample was <8% and <10%, respectively.Alkylresorcinol concentrations in adipose tissue biopsies were analyzed using a recently developed high throughput GC-MS method , with slBaseline characteristics for the subcohort and the cases are presented as numbers and percentages for categorical variables and as medians with 5th and 95th percentiles for continuous variables. Whole grain rye and wheat intakes levels estimated from FFQ were correlated with alkylresorcinol concentrations in the adipose tissue using Spearman’s rank correlation. We applied a case-cohort design as previously described  and used(1)Crude FFQ models: WGRWGW + WGR% + Total energy intake.(2)Multivariate-adjusted FFQ models: Energy-adjusted WGRWGW  + WGR% + Total energy intake + Other breast cancer risk factors.(3)Crude biomarker models: Total alkylresorcinol concentration in adipose tissue + Alkylresorcinol C17:0/C21:0 ratio in adipose tissue.(4)Multivariate-adjusted biomarker models: Total alkylresorcinol concentration in adipose tissue + Alkylresorcinol C17:0/C21:0 ratio in adipose tissue + Other breast cancer risk factors.Instead of “whole grain rye intake” and “whole grain wheat intake”, “total whole grain rye and wheat intake” and “relative whole grain rye intake” were the exposures of main interest, since they might better reflect the quantity and quality of whole grain-related dietary fiber and bioactive compound intake. “Total whole grain rye and wheat intake” and “relative whole grain rye intake” were estimated from FFQ and used as independent exposure variables: WGRWGW and WGR% (FFQ models), or reflected by total alkylresorcinol concentration and alkylresorcinol C17:0/C21:0 ratio, respectively, in adipose tissue (biomarker models). WGRWGW and WGR% in FFQ models, and total alkylresorcinol concentration and alkylresorcinol C17:0/C21:0 ratio in adipose tissue in biomarker models, were specified continuously with a one-unit increase, representing a 10 g/day increment in WGRWGW and a 10% increase in WGR%, or a 1 nmol/g increment in total alkylresorcinol concentration in adipose tissue and a 0.1 unit increase in alkylresorcinol C17:0/C21:0 ratio in adipose tissue. These exposures were also categorized according to quartiles among all participants and entered into separate models with the lowest quartile as the reference. Hazard Ratio (HR) with 95% confidence intervals (CI) was calculated for:2), education , parity , age at first birth , age at first period (<12 or ≥12), menopause status at baseline (pre/post), menopausal hormone use (never/former/current), physical activity (<30 or ≥30 min/day), smoking (never/former/current), and alcohol intake (continuous variable).“Other breast cancer risk factors” included established breast cancer risk factors at baseline, including body mass index (BMI)  as exposure in hormones  and becaP < 0.05 was considered significant. The MEANS and FREQ procedures in SAS were used for descriptive analyses. The CORR procedure was used for correlation analyses and the PHREG procedure was used for the Cox proportional hazard models.SAS statistical analysis software  was used for all tests and The baseline characteristics of cases and of the subcohort are presented in r = 0.13, P < 0.001), whole grain rye intake , and total whole grain rye and wheat intake . Alkylresorcinol C17:0/C21:0 ratio was correlated with WGR% . Total alkylresorcinol concentration in adipose tissue was significantly correlated with whole grain wheat intake , but not with any increased risk of developing ER- breast cancer.Women in the fourth quartile (Q4) of WGR% had a 60% higher risk of developing breast cancer, or a 62% higher risk of developing ER+ breast cancer, than women in Q1, while a non-significant dose-response trend was observed across Q1–Q4. However, a consistent, dose-dependent positive association was observed between alkylresorcinol C17:0/C21:0 ratio in adipose tissue and risk of total breast cancer, with 7–9% higher risk of overall breast cancer per 0.1 unit increment in the ratio in the crude and multivariable-adjusted models . AlkylreIn this study, where whole grain rye and wheat intake were assessed using both questionnaire data and a long-term biomarker, no overall association was found between total whole grain rye and wheat intake and the risk of breast cancer. However, sub-analysis revealed that higher alkylresorcinol C17:0/C21:0 ratio, reflecting higher relative whole grain rye intake, was associated with a higher risk of breast cancer, a finding which warrants further investigation.Our study has several limitations. Firstly, we only had access to samples and data from women who developed breast cancer between 2001 and 2006, which means long latency between single determinations of whole grain intake/alkylresorcinol concentrations in adipose tissue, which occurred at baseline (1993–1997), and the development of breast cancer. Secondly, our biomarkers only reflected the intake of whole grain rye and wheat, and not that of other whole grains such as oats, since alkylresorcinol are not present in oats. Thirdly, the role of potential dietary and non-dietary determinants of alkylresorcinol C17:0/C21:0 ratio in adipose tissue, other than whole grain rye and wheat intake, has not been studied in detail so far and, therefore, our results might be confounded by as yet unknown factors. However, our study also has several strengths. Firstly, Nordic adults seem to maintain a rather stable whole grain intake , which mTotal alkylresorcinol concentrations and C17:0/C21:0 ratio in adipose tissue observed in the present study were similar to those reported previously for Swedish subjects, but somewhat lower than reported for Finnish subjects ,52,79, vTotal whole grain rye and wheat intake  were not associated with the risk of developing breast cancer in the present study. This finding is in agreement with results from a prospective cohort analysis including all women in the Danish Diet, Cancer and Health cohort study . Our resThe lack of association between total whole grain rye and wheat intake might also be due to whole grain rye and whole grain wheat being differently associated with the risk of developing breast cancer, which has been difficult to examine in previous studies. In the present study, and in the previous prospective analysis in the same population , there wWe found no evidence of a protective role of high total whole grain rye and wheat intake, estimated by FFQ and reflected by total alkylresorcinol concentration in adipose tissue, against the development of breast cancer in the study population of Danish women. However, we found that a higher alkylresorcinol C17:0/C21:0 ratio in adipose tissue, which partly reflects higher relative whole grain rye to whole grain wheat intake and a high intake of alkylresorcinol C17:0, was associated with a higher incidence of ER+ breast cancer. This observation was confirmed by a similar finding for relative whole grain rye to whole grain wheat intake data from FFQ models. This warrants further studies on the role of different grains, the use of C17:0/C21:0 ratio in adipose tissue as a biomarker in relation to breast cancer risk, and the potential role of the short alkylresorcinol homolog C17:0 in the risk of developing ER+ breast cancer.


Breast cancer chemoprevention can reduce breast cancer incidence in high-risk women; however, chemoprevention is underutilized in the primary care setting. We conducted a pilot study of decision support tools among high-risk women and their primary care providers (PCPs).RealRisks, and a provider-centered tool, Breast Cancer Risk Navigation (BNAV). Patients completed validated surveys at baseline, after RealRisks and after their PCP clinical encounter or at 6-months. Referral for high-risk consultation and chemoprevention uptake were assessed via the electronic health record. The primary endpoint was accuracy of breast cancer risk perception at 6-months.The intervention included a decision aid (DA) for high-risk women, RealRisks, patients demonstrated an improvement in accurate breast cancer risk perceptions (p = 0.02), an increase in chemoprevention knowledge (p < 0.01), and 24% expressed interest in taking chemoprevention. Three women had a high-risk referral, and no one initiated chemoprevention. Decisional conflict significantly increased from after exposure to RealRisks to after their clinical encounter or at 6-months (p < 0.01). Accurate breast cancer risk perceptions improved and was sustained at 6-months or after clinical encounters. We discuss the side effect profile of chemoprevention and the care pathway when RealRisks was introduced to understand why patients experienced increased decision conflict.Among 40 evaluable high-risk women, median age was 64.5 years and median 5-year breast cancer risk was 2.19%. After exposure to Future interventions should carefully link the use of a DA more proximally to the clinical encounter, investigate timed measurements of decision conflict and improve risk communication, shared decision making, and chemoprevention education for PCPs. Additional work remains to better understand the impact of decision aids targeting both patients and providers.ClinicalTrials.gov Identifier: NCT02954900 November 4, 2016 Retrospectively registered. Breast cancer is the most common cancer among women in the United States, with an estimated 1 in 8 women developing invasive breast cancer during her lifetime . Women wGuide to Decide, a decision aid that informed high-risk postmenopausal women about potential chemoprevention benefits and side effects resulted in no tamoxifen uptake and only 0.5% uptake of raloxifene  an an15] an limited . This prRealRisks DA. Additionally, we had higher than anticipated loss to follow-up of about 20%. Our short-term follow-up of 6 months may have been insufficient to assess clinical outcomes such as high-risk clinic referrals and actual chemoprevention uptake.Limitations of our study include the lack of a concurrent control arm, the relatively small sample size, and conducting the study in an urban academic center with access to a high-risk clinic, all of which limit the generalizability of our findings. In addition, although we found no significant differences in age, race, and racial distribution between the pilot sample and KYRAS high-risk patients, our sample was self-selected from the larger KYRAS screening study. The study sample was older than what we expected and may not be totally representative of a higher risk younger population who are likely more appropriate for chemoprevention and the We developed decision support tools for both patients and their PCPs, which include personalized risk reports and education about breast cancer risk and chemoprevention. Our study population was racially and ethnically diverse and our patient-centered DA, which is available in English and Spanish, was rigorously tested in women of multiple ethnicities with varying levels of health literacy and numeracy. In addition to using validated outcome measures, we were able to assess referrals to the high risk breast clinic and actual chemoprevention uptake using electronic health records.RealRisks and BNAV (NCT03069742). We will target younger, healthier women with higher breast cancer risk, including those with high-risk benign breast lesions such as atypical hyperplasia and lobular carcinoma in situ. These women are likely to derive a greater benefit from breast cancer risk reduction and a lower risk of serious side effects. To reinforce use of the patient-centered RealRisks DA, we will set up automated reminders to revisit the tool prior to their next PCP clinical encounter, next screening mammography visit, and birthday (as breast cancer risk increases with advancing age). We will enhance provider engagement with an enhanced BNAV tool, which will offer continuing medical education (CME) credit and additional modules on breast cancer screening and other topics relevant to PCPs. We have already developed modules on risk communication and shared decision making. We will elicit patient preferences for chemoprevention, specifically factors that are most important and least important to chemoprevention decisions, which we will summarize for providers prior to the clinical encounter. Even if we do not observe a significant increase in chemoprevention uptake with the addition of RealRisks and BNAV compared to standard educational materials, our goal is to also increase informed choice, decrease decision conflict, and facilitate SDM during the clinical encounter. Facilitating discussions about breast cancer chemoprevention between clinicians and high-risk women is in accordance with recommendations from the U.S. Preventive Services Task Force (USPSTF), American Society for Clinical Oncology (ASCO), National Comprehensive Cancer Network (NCCN), and the National Institute for Health and Care Excellence (NICE) [The results of our initial pilot study have informed the design and conduct of a larger randomized controlled trial of 300 high-risk women assigned to standard educational materials alone or in combination with e (NICE) –11.