Biological Heterogeneity Of Breast Cancer In Relation To Menarche Age,Menopause Age And Reproductive Years:A Hospital-based Retrospective Epidemiological Study

Objective: Menarche and menopause are signals of onset and cessation of ovarian and reproduction-correlated endocrine activity,respectively,both of which are crucially associated with breast cancer.The length of reproductive years is represented by the total time period of exposure to cycling reproductive hormones,calculated from age at menarche to age at menopause.Methods: Unconditional logistic regression was performed to assess the associations between clinicopathological features and menarche age,menopause age,and reproductive years.The differences in risk factors between lower and higher number of reproductive years(<35 and ?35 yrs)were examined with the chi-square test.Results: Breast cancer patients with late menarche age were more likely to present with tumors of higher histological grade and larger sizes.The results suggested higher likelihood of smaller tumor sizes and higher histological grade in postmenopausal patients with a greater length ofreproductive years.In the luminal breast cancer group,a negative association between length of reproductive years and tumor size was evident among postmenopausal patients.In patients with triple negative breast cancer,greater length of reproductive years was more likely to show advanced axillary lymph node metastasis.Conclusion: Our findings indicated that breast cancer patients with early menarche age have more unfavourable clinicopathologic feature.In luminal breast cancer,greater length of reproductive years might be a favourable factor,which is associated with smaller tumor sizes.In triple negative breast cancer,greater length of reproductive years might be a unfavourable factor,which is associated with advanced axillary lymph node metastasis.