Selected Medical Interventions in Women With a Deleterious Brca Mutation: A Population-Based Study in British Columbia

Background: We examined the uptake of risk-reducing interventions, including bilateral mastectomy, risk-reducing salpingo-oophorectomy, oral contraceptive pills, tamoxifen, and raloxifene, for the entire population of women with a deleterious BRCA1 or BRCA2 mutation in the Canadian province of British Columbia. Methods: This retrospective population-based study used data available in British Columbia for all women who, between 1996 and 2014, were tested and found to have a BRCA mutation. Rates of risk-reducing interventions stratified according to the type of BRCA mutation and prior history of breast or gynecologic cancer (ovary, fallopian tube, peritoneal) are presented. Cancers diagnosed in women with a BRCA mutation after disclosure of their mutation status are also presented. Results: The final study cohort consisted of 885 patients with a deleterious BRCA1 (n = 474) or BRCA2 (n = 411) mutation. Of the women with no prior breast cancer, 30.8% carrying a BRCA1 mutation and 28.3% carrying a BRCA2 mutation underwent bilateral mastectomy. Of women with no prior gynecologic cancer, 64.7% carrying a BRCA1 mutation and 62.2% carrying a BRCA2 mutation underwent risk-reducing bilateral salpingo-oophorectomy. Rates of chemoprevention with oral contraceptive pills and tamoxifen or raloxifene were low in all groups. In this cohort, 23 gynecologic and 70 breast cancers were diagnosed after disclosure of BRCA mutation status. Conclusions: Our results suggest reasonable uptake of risk-reducing interventions in high-risk women. To minimize the occurrence of breast and ovarian cancer in women with a BRCA1 or BRCA2 mutation, more attention could be paid to ensuring that affected women receive proper counselling and follow-up.