Objectives: Surgical therapy for invasive breast cancer includes breast conservation therapy (BCT), unilateral mastectomy (UM), or bilateral mastectomy, including contralateral prophylactic mastectomy (CPM) with or without reconstruction (±R). The goal of this study was to determine factors associated with CPM. Methods: A breast cancer database collected from 2000 through 2008 was retrospectively reviewed. Treatment groups analyzed included BCT, UM ± R, and CPM ± R. Variables were compared using ANOVA F-tests and chi-square tests. Multivariate analysis was performed using logistic regression. Results: A total of 1,391 patients underwent surgery for invasive breast cancer: 69% BCT, 21% UM, and 10% bilateral mastectomy. Of those undergoing bilateral mastectomy, 30% had bilateral cancer and were excluded from analysis. The rate of CPM increased significantly from 0 to 20% (p < 0.001), whereas the rate of UM remained relatively stable. Factors associated with CPM included younger age, significant family history, genetic testing, positive BRCA gene mutation, and preoperative magnetic resonance imaging (MRI). Tumor characteristics associated with CPM included positive axillary lymph node metastases and triple-negative disease (ER-/PR-/HER2 normal). Breast reconstruction was more common among women who underwent CPM (p < 0.001). On multivariate regression comparing BCT with CPM, younger age, larger tumors, multifocal disease, and MRI significantly predicted CPM. Comparing UM with CPM, only age and genetic testing significantly predicted CPM. Conclusions: The rate of bilateral mastectomy for unilateral breast cancer is increasing. This is particularly true for younger patients with strong family history. The availability of breast reconstruction may play a role and the effects of stage and multifocal disease needs further exploration.
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