Social and Clinical Determinants of Contralateral Prophylactic Mastectomy.

Importance: The growing rate of contralateral prophylactic mastectomy (CPM) among women diagnosed as having breast cancer has raised concerns about potential for overtreatment. Yet, there are few large survey studies of factors that affect women's decisions for this surgical treatment option.
Objective: To determine factors associated with the use of CPM in a population-based sample of patients with breast cancer.
Design, Setting, and Participants: A longitudinal survey of 2290 women newly diagnosed as having breast cancer who reported to the Detroit and Los Angeles Surveillance, Epidemiology, and End Results registries from June 1, 2005, to February 1, 2007, and again 4 years later (June 2009 to February 2010) merged with Surveillance, Epidemiology, and End Results registry data (n = 1536). Multinomial logistic regression was used to evaluate factors associated with type of surgery. Primary independent variables included clinical indications for CPM (genetic mutation and/or strong family history), diagnostic magnetic resonance imaging, and patient extent of worry about recurrence at the time of treatment decision making.
Main Outcomes and Measures: Type of surgery received from patient self-report, categorized as CPM, unilateral mastectomy, or breast conservation surgery.
Results: Of the 1447 women in the analytic sample, 18.9% strongly considered CPM and 7.6% received it. Of those who strongly considered CPM, 32.2% received CPM, while 45.8% received unilateral mastectomy and 22.8% received breast conservation surgery (BCS). The majority of patients (68.9%) who received CPM had no major genetic or familial risk factors for contralateral disease. Multivariate regression showed that receipt of CPM (vs either unilateral mastectomy or breast conservation surgery) was significantly associated with genetic testing (positive or negative) (vs UM, relative risk ratio [RRR]: 10.48; 95% CI, 3.61-3.48 and vs BCS, RRR: 19.10; 95% CI, 5.67-56.41; P < .001), a strong family history of breast or ovarian cancer (vs UM, RRR: 5.19; 95% CI, 2.34-11.56 and vs BCS, RRR: 4.24; 95% CI, 1.80-9.88; P = .001), receipt of magnetic resonance imaging (vs UM RRR: 2.07; 95% CI, 1.21-3.52 and vs BCS, RRR: 2.14; 95% CI, 1.28-3.58; P = .001), higher education (vs UM, RRR: 5.04; 95% CI, 2.37-10.71 and vs BCS, RRR: 4.38; 95% CI, 2.07-9.29; P < .001), and greater worry about recurrence (vs UM, RRR: 2.81; 95% CI, 1.14-6.88 and vs BCS, RRR: 4.24; 95% CI, 1.80-9.98; P = .001).
Conclusions and Relevance: Many women considered CPM and a substantial number received it, although few had a clinically significant risk of contralateral breast cancer. Receipt of magnetic resonance imaging at diagnosis contributed to receipt of CPM. Worry about recurrence appeared to drive decisions for CPM although the procedure has not been shown to reduce recurrence risk. More research is needed about the underlying factors driving the use of CPM.