Contralateral prophylactic mastectomy (CPM) has been performed for several decades in patients with unilateral breast cancer (BC). However, the survival benefits of CPM are controversial, particularly in young women.
The clinical data of 69,000 young female patients (age ≤ 40 years) who were diagnosed to have unilateral BC and underwent UM or CPM between January 1, 2000 and December 31, 2019 were retrieved from the Surveillance, Epidemiology, and End Results (SEER) database. The following patients were excluded from the final analysis: age > 40 years, male, those with unconfirmed pathological diagnosis, those with bilateral BC, those lacking SEER cause-specific death classification, those lacking months of survival data, and those with uncertainty regarding UM or CPM.Propensity score matching (PSM) was performed between the CPM and UM groups. The overall survival (OS) rate and BC-specific survival (BCSS) rate were determined for both groups.
A total of 36528 patients (21600 and 14928 patients in the UM and CPM groups, respectively) were included in this study. The mean (SD) age of follow-up was 35.5 (4.0) years. The relative rate of CPM increased from 12.3% in 2000 to 55.7% in 2013 and then gradually decreased to 47.4% in 2019. After PSM, 13089 patients remained in each group. The CPM group showed a higher 5-year OS rate (82.1% vs. 75.8%) and a higher 5-year BCSS rate (83.5% vs. 77.7%) than the UM group. Multivariate Cox proportional hazards regression analysis showed that CPM significantly decreased 25% risk of all-cause mortality (OS, hazard ratio [HR]: 0.75, 95% confidence interval [CI]: 0.70–0.80, P < 0.001) and 25% risk of BC-specific mortality (BCSS, HR: 0.75, 95% CI: 0.70–0.80; P < 0.001) in young BC patients as compared to UM. Almost consistent results were observed in subgroup analyses based on different TNM stages, molecular subtypes, race, tumor grade, marital status, radiotherapy status, and chemotherapy status, except for some.
This study suggests that CPM improved OS and BCSS benefits in young BC patients as compared to UM. Randomized clinical trials with a larger sample size are required in the future to confirm these results.
The authors would like to thank the anonymous reviewers for their insightful suggestions and careful reading of the manuscript.
Chong Qing Medical University.
Has not received any funding.
The author has declared no conflicts of interest.