Evaluating the impact of preoperative breast magnetic resonance imaging on the surgical management of newly diagnosed breast cancers.

HYPOTHESIS Women with newly diagnosed breast cancers may harbor additional ipsilateral or contralateral breast malignancies that are undetected by mammography and ultrasonography. Magnetic resonance imaging (MRI) has demonstrated excellent sensitivity in the detection of breast cancers. However, the impact of routine MRI on the surgical management of new, biopsy-proven breast cancers remains unclear. DESIGN Retrospective analysis of a prospective database. SETTING An academic, tertiary care center in a large metropolitan area. PATIENTS A total of 155 women with breast cancer newly diagnosed by mammography, ultrasonography, and needle biopsy underwent preoperative bilateral breast MRI in a single-institution, single-surgeon setting during 1 year. MAIN OUTCOME MEASURES Change in surgical management based on breast MRI findings. RESULTS The MRI demonstrated 124 additional suspicious lesions in 73 patients. Post-MRI follow-up mammograms or ultrasonograms were required in 65 patients, and 41 patients underwent additional image-guided biopsies. There was a change in surgical management as MRI discovered additional, otherwise undetected malignancies in 36 patients based on radiographic-pathologic correlation. Lumpectomy was converted to mastectomy in 10 patients (8 beneficial), wider excision was performed in 21 patients (10 beneficial), and 5 patients (2 beneficial) underwent contralateral surgery. Larger tumor size was an independent predictor of a beneficial change in surgical management (odds ratio, 1.66; 95% confidence interval, 1.04-2.66). CONCLUSIONS Breast MRI results in a beneficial change in surgical management in 9.7% of newly diagnosed breast cancers. The detection of additional, otherwise undetected ipsilateral and contralateral breast malignancies with MRI suggests that breast MRI may have a role in the evaluation of new breast cancers.