Prior studies have indicated that removal of the ovaries and fallopian tubes reduces the ovarian cancer risk by ~80% and breast cancer risk by ~50%, particularly when performed pre-menopausally. However a recent case control study of 2854 pairs of women with a BRCA1 or BRCA2 mutation with or without breast cancer showed that the risk of breast cancer was lowered more in those with surgical menopause (OR, 0.52; 95% CI, 0.40–0.66) compared to those with natural menopause (OR, 0.81; 95% CI, 0.62–1.07). Interestingly, this study also found that there was a significant reduction in breast cancer risk even in women who had their ovaries removed after they went through natural menopause (OR, 0.13; 95% CI, 0.02–0.54; P = 0.006). This is an important finding because women with BRCA mutations who remove their ovaries after menopause typically do so to lower their ovarian cancer risk – however, this study suggests that they also may be reducing their breast cancer risk at the same time. Finding from this study also highlight the importance for better understanding the protective effect of oophorectomy, as this has very important implications for chemoprevention.
Kotsopoulos J, et al. Cancer Epidemiol Biomarkers Prev. 2012 Jul; 21(7):1089-96.