Contralateral Prophylactic Mastectomy Decisions in a Population-Based Sample of Patients With Early-Stage Breast Cancer.

Importance: Contralateral prophylactic mastectomy (CPM) use is increasing among women with unilateral breast cancer, but little is known about treatment decision making or physician interactions in diverse patient populations.

Objective: To evaluate patient motivations, knowledge, and decisions, as well as the impact of surgeon recommendations, in a large, diverse sample of patients who underwent recent treatment for breast cancer.

Design, Setting, and Participants: A survey was sent to 3631 women with newly diagnosed, unilateral stage 0, I, or II breast cancer between July 2013 and September 2014. Women were identified through the population-based Surveillance Epidemiology and End Results registries of Los Angeles County and Georgia. Data on surgical decisions, motivations for those decisions, and knowledge were included in the analysis. Logistic and multinomial logistic regression of the data were conducted to identify factors associated with (1) CPM vs all other treatments combined, (2) CPM vs unilateral mastectomy (UM), and (3) CPM vs breast-conserving surgery (BCS). Associations between CPM receipt and surgeon recommendations were also evaluated. All statistical models and summary estimates were weighted to be representative of the target population.

Main Outcomes and Measures: Receipt of CPM was the primary dependent variable for analysis and was measured by a woman's self-report of her treatment.

Results: Of the 3631 women selected to receive the survey, 2578 (71.0%) responded and 2402 of these respondents who did not have bilateral disease and for whom surgery type was known constituted the final analytic sample. The mean (SD) age was 61.8 (12) years at the time of the survey. Overall, 1301 (43.9%) patients considered CPM (601 [24.8%] considered it very strongly or strongly); only 395 (38.1%) of them knew that CPM does not improve survival for all women with breast cancer. Ultimately, 1466 women (61.6%) received BCS, 508 (21.2%) underwent UM, and 428 (17.3%) received CPM. On multivariable analysis, factors associated with CPM included younger age (per 5-year increase: odds ratio [OR], 0.71; 95% CI, 0.65-0.77), white race (black vs white: OR, 0.50; 95% CI, 0.34-0.74), higher educational level (OR, 1.69; 95% CI, 1.20-2.40), family history (OR, 1.63; 95% CI, 1.22-2.17), and private insurance (Medicaid vs private insurance: OR, 0.47; 95% CI, 0.28-0.79). Among 1569 patients (65.5%) without high genetic risk or an identified mutation, 598 (39.3%) reported a surgeon recommendation against CPM, of whom only 12 (1.9%) underwent CPM, but among the 746 (46.8%) of these women who received no recommendation for or against CPM from a surgeon, 148 (19.0%) underwent CPM.

Conclusions and Relevance: Many patients consider CPM, but knowledge about the procedure is low and discussions with surgeons appear to be incomplete. Contralateral prophylactic mastectomy use is substantial among patients without clinical indications but is low when patients report that their surgeon recommended against it. More effective physician-patient communication about CPM is needed to reduce potential overtreatment.