[Using magnetic resonance imaging for staging can change the therapeutic management in patients with breast cancer].

OBJECTIVE To compare two series of patients with breast cancer, one staged using preoperative MRI and the other staged using conventional techniques, analyzing the changes to treatment, the number of mastectomies, and the number of reinterventions due to involvement of the margins. MATERIAL AND METHODS We reviewed 600 patients divided into 300 patients with preoperative MRI (series 1) and 300 without preoperative MRI (series 2). We recorded the following variables: age, menopausal status, tumor size on pathological examination, multiplicity and bilaterality, surgical treatment and type of treatment, the administration of neoadjuvant chemotherapy, and reintervention for involved margins. We used Student's t-test and the chi-square test to compare the variables between the two series. RESULTS The mean age of patients in the two series was similar (51.5 and 51.8 years, P=0.71). The mean size of the tumor was smaller in series 1 (16.9 mm vs 22.3 mm) (P<.001). More multiple tumors were detected in series 1 (28.7 vs 15.7%) (P<.001). The rate of mastectomies was lower in series 1 (25 vs 48%) (P<.001). Oncoplastic and bilateral surgeries were performed only in series 1. Neoadjuvant chemotherapy was administered more often in series 1 (30.7 vs 9.3%) (P<.001). The difference in the number of reinterventions for involved margins did not reach significance (7.2% in series 1 vs 3.2% in series 2) (P=.095). CONCLUSION When MRI was used for staging, neoadjuvant chemotherapy and oncoplastic surgery were used more often and the mastectomy rate decreased. Despite the increase in conservative surgery in patients staged with MRI, the number of reinterventions for involved margins did not increase, although there was a trend towards significance.