Negative Genetic Testing Does Not Deter Contralateral Prophylactic Mastectomy in Younger Patients with Greater Family Histories of Breast Cancer.

Background: Increasing rates of contralateral prophylactic mastectomy (CPM) correlate with adoption of total skin-sparing mastectomy (TSSM). We aimed to characterize patients with unilateral breast cancer who underwent TSSM with CPM or without CPM (No CPM).

Methods: We reviewed all patients with unilateral breast cancer who underwent TSSM from 2006 to 2013. Trends in CPM and genetic testing were evaluated across time. Patient characteristics and complications were compared between CPM and No CPM groups.

Results: We identified 591 patients (293 No CPM and 298 CPM) with median follow-up of 25 (interquartile range [IQR] 13-52) months. All patients with deleterious mutations and 58% of those who tested negative for mutations underwent CPM. In patients who tested negative for mutations, CPM was correlated with younger patient age, greater family history, and younger age of relatives diagnosed with breast/ovarian cancer. CPM was associated with an increased risk of superficial nipple necrosis (relative risk [RR] 2.1, 95% confidence interval [CI] 1.12-4.0), wound breakdown (RR 1.62, 95% CI 1.04-2.5), and infections requiring oral antibiotics (RR 1.59, 95% CI 1.16-2.2). In patients with tissue expander/implant reconstruction, CPM was associated with an increased risk of implant exposure (RR 1.95, 95% CI 1.03-3.7) but did not affect the risk of implant loss (RR 0.91, 95% CI 0.56-1.48).

Conclusions: Patients who choose CPM fit the profile of patients with higher risk of contralateral breast cancer (CBC), which may be due to polygenic risk factors that are currently under investigation. Physicians should address patients' fears of CBC, screening concerns, and the risk of complications when considering CPM.