Predictive value of breast magnetic resonance imaging in detecting mammographically occult contralateral breast cancer: Can we target women more likely to have contralateral breast cancer?

Background and Objectives: Preoperative breast magnetic resonance imaging (B-MRI) staging in newly diagnosed breast cancer increases detection of synchronous contralateral findings, but may result in false-positive outcomes. This study objective was to identify women more likely of having mammographically occult, MRI detected contralateral breast cancer (CBC). Methods: We performed a retrospective review of patients who had preoperative B-MRI prior to surgery from 2010 to 2015 and collected patient imaging and clinicopathologic data. Multivariate logistic regression was used to identify predictors of CBC. Results: MRI resulted in contralateral findings in 201 of 1894 patients (10.6%). Overall 3.2% (60 of 1894) had synchronous CBC detected on B-MRI. The majority of CBCs (n=60) were stage 0 or IA (85.0%), hormone receptor positive (94.9%), human epidermal growth factor receptor 2 (HER2/neu) negative (89.7%), and low/intermediate pathological grade (87.2%). Women more likely to have CBC were older (P<.001), had lobular index cancer (P=.03), and estrogen receptor (ER)+ (P=.027) or progesterone receptor (PR)+ (P=.002) tumors. On multivariate analysis (receiver operating characteristic curve area=0.75), PR+ status (P=.022), and older age (P=.004) were predictive of CBC. Conclusions: Preoperative MRI is most effective in detecting early stage, hormone receptor-positive CBC in older women.