Contralateral Proph. Mast.

2011 ASCO Annual Meeting 

 J Clin Oncol 29: 2011 (suppl; abstr 1578)

Author(s): A. M. Brewster, P. A. Parker, I. Bedrosian, W. Dong, S. K. Peterson, S. B. Cantor, M. Crosby, Y. Shen; University of Texas M. D. Anderson Cancer Center, Houston, TX

Background: Contralateral prophylactic mastectomy (CPM) has been shown to reduce the risk of contralateral breast cancer but there is conflicting evidence whether it improves disease-free or overall survival. The objective of the study was to evaluate the clinical benefits of CPM utilizing a large cohort of patients with detailed information available on tumor characteristics, and surgical and systemic treatments. Methods: We included 3,889 female patients with stages I-III breast cancer who were treated at The University of Texas MD Anderson Cancer Center from 1997 to 2009. Cox proportional hazard models were used to estimate the hazard ratio (HR) and 95% confidence interval (CI) for the associations between CPM and disease-free and overall survival. Results: With a median follow-up time of 4.5 years, CPM was associated with improved disease-free survival (HR 0.75, 95% CI 0.59-0.97) adjusted for stage, nuclear grade, hormone receptor status and chemotherapy. The benefit was seen predominately among the hormone receptor-negative (HR 0.60, 95% CI 0.38-0.95) compared to the hormone receptor-positive patients (HR 0.80, 95% CI 0.58-1.10) but the interaction term was not statistically significant. CPM was also associated with improved overall survival (HR 0.74, 95% CI 0.55-0.99) adjusted for age, race, stage, comorbidities, nuclear grade, hormone receptor status and chemotherapy. Conclusions: CPM was associated with an improvement in breast cancer disease-free and overall survival after controlling for known prognostic factors. The improvement in disease-free survival among the CPM group was largely driven by lower breast cancer deaths and contralateral breast cancers. Further identification of subgroups of patients most likely to benefit from CPM could impact the decision making process for patients and their providers.