the number of women with newly diagnosed cervical cancer increases and the percentage of women with cervical cancer in all gynaecological cancers also increases annually in china1 . radical hysterectomy with pelvic lymphadenectomy is the standard surgical treatment for patients with stage ia2-ib1 cervical cancer . but the wide excision of parametrial tissues ( 3 cm ) increases the complications during and after the operation , especially the complications of the urinary system , which severely affect the life quality and the following adjuvant therapy2 , even in robotic sugeries3 . can we decrease the complication by appropriately narrowing the scope of operation in selected patients without affecting the outcomes ? data on this retrospective study was collected from the hospital of obstetrics & gynaecology , shanghai medical college , fudan university , shanghai , china from jan 2008 to dec 2011 , with the approval of ethics committee of hospital . this hospital serves a diverse urban and rural population with over 1.3 million outpatients and 40,000 inpatients annually , and is a largest specialised referral obstetrics & gynaecology teaching hospital located in shanghai which is the largest city in china with 20 million populations . the pathological and clinical data of patients with stage ia2-ib1 cervical cancer who received radical hysterectomy with pelvic lymphadenectomy in this ob / gyn hospital were collected and analyzed . this retrospective study was exempt from irb approval because we only reviewed the clinical histories without revolving any information about patients ' private . immunohistochemical examinations of d2 - 40 and cd31 were described as negative , positive and strong positive . strong positive of d2 - 40 and cd31 meant d2 - 40 and cd31 positive and also with tumor thrombus . those patients with diameter of tumor 2 cm , depth of cervical myometrial invasion<1/2 and without lymph vascular involvement formed the low - risk group , and the others formed the high - risk group . both groups were further divided into two groups according to the resection width of parametrial tissues . those patients with the resection width of parametrial tissues of both sides 3 cm formed group a , and those with the resection width of parametrial tissues of at least one side <3 cm formed group b. the single factor analysis of the pathological and clinical data of patients was made with  test . the relationship of the resection width of parametrial tissues and the patients ' outcomes was analyzed with  test and log - rank . the single factor analysis of the pathological and clinical data of patients was made with  test . the relationship of the resection width of parametrial tissues and the patients ' outcomes was analyzed with  test and log - rank . there were 880 cases of stage ia2-ib1 cervical cancer received radical hysterectomy with pelvic lymphadenectomy in this hospital from jan 2008 to dec 2011 . , there were 31 cases ( 6.0% ) recurred and 26 cases ( 5.1% ) died of cervical cancer during the follow - up period ( from 2 months to 66 months , averaged 39 months ) . the single factor analysis showed that the diameter of tumor was separately related to the depth of cervical myometrial invasion ( p=0.000 ) , the diameter of tumor and the depth of cervical myometrial invasion were both related to lymph vascular involvement ( p=0.000 ) , the diameter of tumor , the depth of cervical myometrial invasion and lymph vascular involvement were all related to parametrial metastases ( p=0.000 ) , shown as table 2 . immunohistochemical examinations of d2 - 40 were applied to 606 cases and examinations of cd31 were applied to 563 cases . cd31 strong positive ( p=0.002 ) and d2 - 40 strong positive ( p=0.016 ) were also the high - risk factors of parametrial metastases ( shown as table 2 ) . the test showed that parametrial metastases were related to the recurrence ( p=0.030 ) and the death ( p=0.019 ) of cervical cancer , but the immunohistochemical indexes were not related to the recurrence or the death of cervical cancer ( p>0.05 ) , shown as table 3 . the parametrial metastases rate and transfer rate of high - risk group were 4.1% and 9.5% , while those of low - risk group were 0% and 1.4% , shown as figure 1 . the difference of progression free survival ( pfs , p=0.006 ) and overall survival ( os , p=0.004 ) ) of low - risk and high - risk groups was statistically significant . the resection width of parametrial tissues ( varied mostly due to tumor size , performance of different surgeons and the objective conditions of patients ) had no statistically significant effect on the recurrence ( p=1.000 ) and the death ( p=1.000 ) of low - risk patients , shown as table 4 . the resection width of parametrial tissues also had no statistically significant effect on the recurrence ( p=0.082 ) and the death ( p=0.147 ) of high - risk patients , shown as table 4 . the resection width of parametrial tissues also had no statistically significant effect on the pfs ( p=0.610 ) and os ( p=0.608 ) of low - risk patients , shown as figure 2 . according to the guideline of nccn 2014 , the standard surgical treatment for patients with stage ia2-ib1 cervical cancer is radical hysterectomy with pelvic lymphadenectomy , which demands wide excision of parametrial tissues ( cardinal ligament 3 - 4 cm , uterosacral ligament3 cm and all vaginal connective tissues ) . the wide excision of parametrial tissues may block pelvic nerves which locate in cardinal ligament and uterosacral ligament , and increase the complications during and after the operation , especially the complications of the urinary system , which may severely affect the life quality and the following adjuvant therapy 2,3 . studies of large samples have shown that the parametrial metastases rate of stage 1b1 cervical cancer is about 5.4 - 10% 4 - 5 . the parametrial metastases rate of those patients with the diameter of tumor 2 cm , the depth of cervical myometrial invasion<10 mm and without lymph vascular involvement is about 0 - 1.1% 4 - 6 , which suggest that these factors can be considered as low - risk factors . on the other hand , there was a report of 37 patients with stage 1a2 - 1b1 cervical cancer showing that the parametrial metastases rate was 33% for all patients and 4.5% for those with the diameter of tumor 2 cm and without lymph vascular involvement7 , but this result should be doubted because of the limited cases and the miss of considering the depth of cervical myometrial invasion . in our study , 880 patients with stage ia2-ib1 cervical cancer were analyzed and the total parametrial metastases rate was 2.4% . the single factor analysis showed that the diameter of tumor > 2 cm , the depth of cervical myometrial invasion 1/2 and lymph vascular involvement were all independent high - risk factors of parametrial metastases . there were no parametrial metastases in cases with the diameter of tumor 2 cm , the depth of cervical myometrial invasion<1/2 and without lymph vascular involvement at the same time , which suggested that over resection of parametrial tissues was not wise for these low - risk patients . can we narrow the range of operation , decrease the possible complications and improve the life quality while without bad effect on the outcomes of these low - risk patients ? the feasibility and safety of narrowing the scope of operation in selected patients are worthy of further discussion . among cases of stage ia2-ib1 cervical cancer which should have received radical hysterectomy with pelvic lymphadenectomy according to the guideline of nccn 2014 , there were 290 ( 56.5% ) cases whose actual resection width of parametrial tissues of at least one side < 3 cm , which is mostly varied mostly due to tumor size , performance of surgeons and the objective conditions of patients . we analyzed these cases and found out that the recurrence rate was 1.4% for low - risk patients , which was lower than 9.5% for other patients . among all low - risk patients , the recurrence rate of those with the resection width of parametrial tissues of at least one side <3 cm ( group b ) was 1.8% , which had no statistically difference with that ( 0.1% ) of patients with the resection width of parametrial tissues of both sides 3 cm ( group a ) . among all high - risk patients , the recurrence rate of group b was 13.5% and also had no statistically difference with that of group a ( 6.3% ) , which may be due to the adjuvant chemotherapy , radiotherapy or both after the operation . the pfs and os of high - risk patients , even with the help of adjuvant chemotherapy , radiotherapy or both after the operation , were still lower than those of low - risk patients . the resection width of parametrial tissues had no statistically significant effect on the pfs and os of low - risk patients and further supported the feasibility and safety of narrowing the range of operation in low - risk patients , which was also supported by another paper 8 . but how can we accurately value those patients of cervical cancer before operation since the staging of cervical cancer is based on clinical characteristics the magnetic resonance imaging ( mri ) and pelvic reconstruction can help with the accurate assessment of the diameter of tumor and the depth of cervical myometrial invasion . so the accurate assessment of lymph vascular involvement becomes a key point of excluding the high - risk factors before operation . the d2 - 40 antibody plays an important role in routine histopathologic diagnostics of normal lymphatic vessels and lymphaticderived tumors 9 . platelet / endothelial cell adhesion molecule-1 ( cd31 ) is a cell adhesion and signaling molecule which plays in the biology of blood and vascular cells 10 . so we used strong positive of d2 - 40 to stand by the lymphatic vessel invasion and strong positive of cd31 to stand by the vascular invasion of cervical cancer , and found out that strong positive of d2 - 40 and cd31 may suggest the parametrial metastases , although the expressive level of cd31 and d2 - 40 had no relationship with the recurrence and death of cervical cancer . so we can make a fairly precise assessment of whether there is lymph vascular involvement or not by immunohistochemical examination of the expressive level of cd31 and d2 - 40 in the specimens of cervical biopsy or loop electrosurgical excision procedure of patients with cervical cancer . the expression status of d2 - 40 and cd31 were not represented by the density of the lymphatic ducts and blood vessels . due to the length of the study and the number of cases included , it was difficult to suggest the exact size of narrowing resection of parametrial tissues which is feasible and safe for low - risk patients . in summary , this retrospective analysis has shown that the diameter of tumor > 2 cm , the depth of cervical myometrial invasion 1/2 and lymph vascular involvement are all independent high - risk factors of parametrial metastases , and further highly related to the outcomes of stage ia2-ib1 cervical cancer . low - risk patients without any of these three high - risk factors have fairly optimistic outcomes , and narrowing the range of operation , which means narrowing resection of parametrial tissues ( < 3 cm ) , is feasible and safe for low - risk patients . mri , combined with the immunohistochemical examination of d2 - 40 and cd31 , can help with excluding the high - risk factors before operation .