- Bilateral mastectomy (BLM) for early breast cancer (eBCa) is not associated with a survival advantage despite cutting the risk for second contralateral breast cancer (CBCa) by a small degree (around 34-43 cases per 10,000 person-years) relative to other surgical procedures.
Why this matters
- BLM for eBCa is increasing in the United States.
- This study suggests that BLM's lack of survival benefit should be weighed against its harms.
- Retrospective cohort (n=245,418) of patients with eBCa stage 0-III from California (1998-2015) in the Surveillance, Epidemiology, and End Results database.
- Absolute excess risk (AER) of CBC was assessed as the observed minus the expected number of BCas in the general population divided by 10,000 person-years at risk.
- Funding: California Department of Public Health; CDC; NIH.
- After a median follow-up of 6.7 years, 3.2% of the cohort developed CBCa.
- AERs were greater after BCT (5.0 more cases per 10,000 person-years at risk) and after ULM (13.6 more cases per 10,000 person-years at risk) vs BLM (28.6 fewer cases per 10,000 years at risk).
- BLM had no different risk for breast cancer death (HR, 1.03; 95% CI, 0.96-1.11) vs BCT.
- ULM had higher risk for breast cancer death (HR, 1.21; 95% CI, 1.17-1.25) vs BCT.
- Retrospective observational design.