A recent study conducted by Kelly Metcalfe and colleagues and published in the British Journal of Cancer in 2024, explores the effectiveness of risk-reducing mastectomy (RRM) in decreasing breast cancer mortality among women carrying the BRCA1 or BRCA2 pathogenic variants.
These genetic mutations significantly increase the risk of developing breast cancer, prompting some carriers to opt for RRM as a preventive measure.
The researchers utilized a registry of women identified with these genetic variants to form their study group. They then employed a pseudo-randomized trial design, pairing each participant who underwent RRM with another participant who did not, based on their year of birth, specific gene variant (BRCA1 or BRCA2), and country of residence.
The main objective of the research was to compare the hazard ratio (HR)—a measure of how the rate of death from breast cancer differs between the two groups during the study period.
The study included 1,654 women, divided evenly between those who had RRM (827 women) and those who did not (827 women).
Over an average follow-up of 6.3 years, the RRM group experienced 20 cases of breast cancer (including 15 that were undetected at the time of surgery) and 2 deaths from breast cancer. Meanwhile, the control group (those who did not have RRM) saw 100 cases of breast cancer and 7 deaths.
The hazard ratio calculated from these outcomes was 0.26 with a 95% confidence interval of 0.05–1.35, and a p-value of 0.11, indicating a non-statistically significant reduction in the risk of dying from breast cancer for those who underwent RRM, though the trend suggests a benefit.
The researchers concluded that for women with a BRCA1 or BRCA2 pathogenic variant, undergoing RRM can reduce the risk of developing breast cancer, and the likelihood of dying from breast cancer after RRM is relatively low, estimated at 0.95% within 15 years post-surgery.
This study provides valuable data on the impact of RRM on breast cancer mortality among high-risk women, despite the non-significant p-value suggesting that more research may be needed to definitively quantify the benefit.
