Trends in contralateral prophylactic mastectomy and genetic testing in the era of new society guidelines.

PURPOSE: In 2016 and 2019 respectively, the American Society of Breast Surgeons published consensus statements discouraging contralateral prophylactic mastectomy (CPM) in average-risk women with unilateral breast cancer and recommending genetic testing be made available for all patients with breast cancer. We sought to evaluate trends in CPM and genetic testing across two academic healthcare systems before and after the publication of the 2016 statement. METHODS: Retrospective chart review was performed from 2011 to 2020 for women with newly diagnosed unilateral stage 0 to III breast cancer who underwent surgery. Patients treated at the University of Kentucky or within the academic health system at the University of Minnesota were included and divided into two cohorts: before the 2016 CPM publication and after. Rates of CPM and genetic testing and factors associated with CPM were evaluated. RESULTS: 6,203 patients were identified. 2,619 patients were diagnosed between 2011 and 2015, and 3,584 were diagnosed between 2016 and 2020. Genetic testing was higher in the later cohort, with 2% prior to 2016 and 22% in 2016 or later. Rates of CPM were similar in the earlier and later cohorts (19% and 15%, respectively; p < 0.001). Factors associated with receipt of CPM were younger age, white race, lobular histology, increasing tumor size, HER2 positivity and genetic testing. CONCLUSION: CPM trends at two academic institutions remained relatively stable over a time period when societal guidelines discouraged the use of CPM in average-risk women with unilateral breast cancer. Further work to understand these trends and identify interventions to reduce the rates of CPM is needed.