The influence of preoperative MRI on breast cancer treatment.

Background: Breast magnetic resonance imaging (MRI) is increasingly used for breast cancer treatment planning. The aim of this study was to evaluate rates of mastectomy and breast-conserving surgery (BCS) in patients who undergo preoperative MRI.
Methods: We retrospectively reviewed charts of patients who underwent surgical treatment of breast cancer at a single center between 2002 and 2009. Exclusion criteria included stage IV disease, previous breast cancer, Hodgkin lymphoma, and positive BRCA status. Univariate and multivariate analysis evaluated differences in patient demographics, surgical management, and tumor characteristics among women who underwent mastectomy compared to BCS.
Results: Patients who underwent MRI were more likely to have mastectomy than those without MRI (43 vs. 28%; P = 0.002). Multivariate analysis revealed that younger age, larger tumor size, positive lymph node status, infiltrating lobular carcinoma, and preoperative MRI were independent predictors for mastectomy (P < 0.05). MRI detected occult contralateral breast cancer in 2.7% of patients. Among patients treated with BCS, preoperative MRI was not significantly associated with lower reexcision rates (MRI, 14%; no MRI, 18%; P = 0.34).
Conclusions: Preoperative MRI was associated with higher rates of mastectomy and detection of occult contralateral breast cancer, but was not associated with lower reexcision rates.