Uptake of risk-reducing medical interventions among female BRCA1/2 pathogenic variant carriers: A population-based study in British Columbia.

Being a female with a germline BRCA1 or BRCA2 pathogenic variant (PV) elevates risks of developing breast and ovarian cancer, and guidelines recommend preventive interventions and increased screening. This study assesses the use of risk-reducing interventions. This population-based retrospective study included all females who tested positive for a BRCA1/2 PV in British Columbia between 1996 and 2019. Using population-based administrative data, we analyzed their interactions with the health care system to ascertain use of risk-reducing interventions until December 31st, 2023. The final cohort included 1920 BRCA1/2 PV carriers. Of those without a prior breast cancer (n = 1021), 20.8% underwent bilateral mastectomy, with declining uptake in recent years. Of those who were within or above the NCCN-recommended age range for risk-reducing bilateral salpingo-oophorectomy (RRBSO) (n = 1342), 71.8% underwent RRBSO, and ∼ 5% underwent risk-reducing salpingectomy. Notably, only 25.4% of patients without a prior ovarian cancer diagnosis underwent surgical risk-reduction within the recommended age range (n = 318/1251). Delays were primarily due to late age at BRCA disclosure. Uptake of chemoprevention was low. After BRCA disclosure, 27 ovarian and 89 breast cancers were diagnosed. The uptake of mastectomy appears to be decreasing, while uptake of RRBSO for ovarian cancer remains high. However, disclosure of most BRCA PV's occurred after the age of recommended RRBSO, delaying their uptake of risk-reducing interventions and resulting in 24 possibly preventable ovarian cancers.