Rate of contralateral prophylactic mastectomy is influenced by preoperative MRI recommendations

Women with breast cancer increasingly undergo contralateral prophylactic mastectomy (CPM). We evaluated the relationship between preoperative magnetic resonance imaging (MRI) findings and CPM. Other clinicopathologic variables associated with CPM choice and the pathology found in the contralateral breast are also reported.

Newly diagnosed breast cancer patients were prospectively enrolled in the University of Iowa Breast Molecular Epidemiology Resource. Patients with stages 0-III breast cancer who underwent mastectomy for the index cancer were eligible for this analysis. Univariate logistic regression and a multivariate model were used to identify factors predictive of CPM.

Among 134 patients (mean age 54.9 years), 53 (39.6 %) chose CPM. On univariate analysis, patients undergoing CPM were more likely to have a preoperative breast MRI (64.2 vs. 39.5 %, p = 0.006) and to have follow-up testing recommended for the contralateral breast (28.3 vs. 4.9 %, p = 0.001). Univariate analysis also associated CPM with younger age (p < 0.0001), BRCA testing (p < 0.0001), BRCA mutation (p = 0.034) and reconstruction performed (p = 0.001). Median age of youngest child at diagnosis varied significantly between the CPM (15.9 years) and non-CPM (24.3 years) groups (p = 0.0018). On multivariate analysis, MRI follow-up recommendation, young age, reconstruction and human epidermal growth factor receptor 2 (HER2) positivity of the index cancer were significantly associated with CPM. Of the CPM specimens, one (1.8 %) had ductal carcinoma-in situ, which had not been identified on MRI.

Abnormal findings in the contralateral breast on preoperative MRI, as well as young age, reconstruction and HER2-positive status correlated with CPM choice in this cohort. Occult malignancy was rare.