Contralateral Prophylactic Mastectomy: The Argument for Bilateral Mastectomies and Reconstruction

Background: The increasing trend of women with unilateral breast cancer to electively undergo contralateral prophylactic mastectomy (CPM) in addition to treatment of the index breast has been the source of much debate. This trend has been primarily patient-driven, with conflicting, objective evidence supporting CPM. Critics have cautioned against the rising rates of CPM, questioning its indications and the possibility of increased risk over unilateral treatment. As such, any information that can help practitioners better guide their patients towards the most beneficial and risk-reducing options is critical. The authors set out to better frame the risks and benefits of CPM in the treatment of unilateral breast cancer by evaluating outcomes of a large, consecutive cohort of patients.

 

Methods: An IRB-approved review of a single-surgeon (NT) experience (2013-2018) was conducted of all consecutive patients with unilateral breast cancer treated with mastectomy and immediate reconstruction. Demographic data, comorbidities, and surgical pathology results were assessed. Thirty-day complication rates were recorded, including medical complications requiring readmission to the hospital and surgical complications requiring a return to the operating room. Outcomes were compared between patients with unilateral cancer who underwent unilateral mastectomy (UM) versus bilateral mastectomy (one breast being CPM). Logistic regression models evaluated various risk factors for potential associations with positive pathology in the CPM specimen and/or postoperative complications.

 

Results: A total of 244 patients were identified, 146 (59.8%) of which had autologous reconstruction and 98 (40.2%) had implant-based reconstruction. Of the 244 patients, 68 (27.9%) underwent UM and 176 (72.1%) underwent CPM. Of those undergoing CPM, surgical pathology results of the prophylactic breast revealed occult ductal carcinoma in situ or invasive cancer in 13 patients (7.39%) and lobular carcinoma in situ in 8 patients (4.55%). Logistic regression analysis showed no significant association between positive breast pathology and any of the potential factors assessed, including tobacco use, history of radiotherapy, or breast cancer (BRCA) gene status. Incidence of medical complications (4.41% UM vs. 5.68% CPM; p<1.00) and surgical complications (16.18% UM vs. 8.52% CPM; p<0.104) were similar between UM and CPM patients. With UM and CPM patients analyzed in aggregate, multivariable logistic regression revealed increased BMI as a significant risk factor for medical complications (OR=1.15; 95% CI 1.05 to 1.26). Regression models also identified diabetes mellitus to be significantly associated with having a surgical complication (OR=4.05; 95% CI 1.38 to 11.91).  

 

Conclusions: These results underscore the premise that women with unilateral breast cancer who elect to undergo CPM may have an oncologic benefit by identifying an occult neoplasm in patients who lack typical risk factors associated with bilateral disease, such as positive BRCA status. Moreover, the findings presented here also suggest CPM does not pose an increased risk of complications compared to unilateral treatment.