Is contralateral prophylactic mastectomy (CPM) overused? Results from a population-based study.

Abstract

26 Background: The growing rate of CPM among women diagnosed with breast cancer has raised concerns about potential for over-treatment yet, little is known about factors that affect the decisions for this surgical treatment option. Methods: We surveyed 2,245 women newly diagnosed with breast cancer and reported to the Detroit and Los Angeles SEER registries from 6/05-2/07. We merged these data to SEER and re-surveyed them again approximately 4 years later (n=1,525). The primary outcome was receipt of CPM. We modeled surgical treatment decision making in two stages: any mastectomy (including CPM) vs. lumpectomy, and CPM vs. unilateral mastectomy (UM) among mastectomy-treated patients. The primary independent variable was clinically significant risk of developing contralateral disease (family history of at least 2 family members with breast cancer and/or a positive genetic test). We also evaluated the degree to which worry about recurrence drove initial treatment decisions (very vs. somewhat/not at all) and controlled for race/ethnicity, age, stage and SEER site. Results: Of the 1,446 women who had not had a recurrence of breast cancer by the time 2 survey, 35% considered CPM and 7.4% received it. Among those who received a mastectomy for the affected breast the figures were 53% and 19%, respectively. About 70% of patients who received CPM were clinically at very low risk for contralateral disease. 90% of those who got CPM reported being very worried about recurrence when making their treatment decision, compared to 80% of those who received UM (p<0.05). Multivariate regression showed that receipt of CPM vs. UM was associated with having a family history (OR 5.1; 95% CI: 2.49-10.1) and a positive genetic test (OR: 10.93; 95% CI: 3.37-35.71), but was also associated with greater worry about recurrence (OR: 2.07; 95% CI: 1.01-4.51). Conclusions: Many women considered CPM despite the fact that very few of them had clinically significant risk of contralateral breast cancer. Most women who had CPM did not have a clinical indication for considering it and thus not expected to benefit in terms of disease free survival. More research is needed about the underlying factors driving decision-making for CPM.