Hysterectomy, Oophorectomy, Exogenous Hormone Usage, and Brain Cancer Risk in Post-Menopausal Women in CPS-II

Brain cancer rates differ by sex with males experiencing higher rates of malignant brain tumors than females, and rates of non-malignant brain tumors being higher in females. The cause of these differences remains unknown. Previous reports on brain cancer risk factors have proposed that variable exposure to sex hormones throughout one’s life could be an explanation for these sex differences. However, studies investigating various proxy measures of sex hormones (e.g. exogenous hormone usage) have yet to find a consistent association between these and brain cancer risk. In this study, we used data from the American Cancer Society’s Cancer Prevention Study II (CPS-II) and Nutrition Cohorts (CPSII-NC) to evaluate the association between hysterectomy, oophorectomy, oral contraceptive (OC) usage, and menopausal hormone therapy (MHT) usage, and brain cancer risk in post-menopausal women. Cox PH models stratified by age at baseline and adjusted for covariates were used to evaluate these relationships. A positive association was found between hysterectomy and brain cancer in both CPS-II and CPSII-NC. Associations for oophorectomy, OC, and MHT usage were largely null or merely suggestive. Further research on hysterectomy and brain cancer is needed to solidify these findings and find the mechanism behind the association.