A study co-led by Professor Kelly Metcalfe of the Lawrence Bloomberg Faculty of Nursing, Canada, in collaboration with researchers at the Familial Breast Cancer Research Unit at Women’s College Hospital, has revealed that risk-reducing mastectomies (RRM) in women with BRCA1 or BRCA2 genetic variants significantly decrease the risk of breast cancer diagnosis and mortality.
Published in the British Journal of Cancer, the study investigated the impact of RRM on mortality rates among women with a pathogenic variant but no history of cancer diagnosis.
Until now, there has been only one other study, conducted by researchers in the Netherlands, that examines the effects of RRM on mortality and quantifies its benefits for women.
“The decision to undergo risk-reducing mastectomy can be challenging for women, and providing them with more evidence during this decision-making process can help inform their care plan,” says Metcalfe, who also serves as a Senior Scientist at Women’s College Research Institute.
Women with an inherited BRCA1 or BRCA2 variant face an 80 percent lifetime risk of developing breast cancer. Studies have shown that RRM reduces this risk by 90 percent, with approximately 30 percent of Canadian women with a pathogenic variant opting for this surgery.
Metcalfe emphasizes that RRM is one of the most effective preventive measures for women with this genetic risk profile.
Through a pseudo-randomized trial, Metcalfe and her team tracked over 1600 participants from a registry of women with a pathogenic BRCA1/2 variant across nine different countries over six years, with half of the women undergoing RRM.
At the conclusion of the trial, the group that opted for RRM experienced 20 incident breast cancers and two deaths, while the control group had 100 incident breast cancers and seven deaths. RRM reduced the risk of breast cancer by 80 percent, with the probability of dying from breast cancer 15 years after RRM being less than one percent.
“While there wasn’t a significant difference in deaths between the two groups in this study, we know that risk-reducing mastectomy significantly decreases the risk of ever developing breast cancer,” Professor Kelly Metcalfe.
Metcalfe highlights the need for continued monitoring of participants over an extended period to gather more evidence on mortality risk and the benefits associated with RRM.
“Currently, we have effective screening methods in place for breast cancer, including breast MRI, so surgery is presented as an option rather than a recommendation,” explains Metcalfe. “But with ongoing studies assessing women’s outcomes and risk factors following RRM, we will gain insight into whether these guidelines need revision in the future.”
