Impact of preoperative breast MRI on locoregional staging and management in early breast cancer.

e12510 Background: The role of preoperative breast MRI in early breast cancer remains controversial. We evaluated the impact of MRI compared with mammography and ultrasonography on staging accuracy and treatment decisions. Methods: We conducted a retrospective cohort study of 154 patients with early breast cancer who underwent preoperative mammography, ultrasonography, and breast MRI. Imaging findings were compared within the same patients. Changes in staging, lymph node positive finding, and treatment recommendations following MRI were investigated. Results: Breast MRI detected multicentric disease in 26.0% of patients versus 7.8% on conventional imaging and upstaged tumors to T3 in 7.1% of cases not identified by mammography or ultrasonography. MRI identified lymph node involvement in 31.2% of patients compared with 22.1% on ultrasonography. Overall, MRI led to changes in staging or treatment decisions in 31% (48/154) of patients. Breast-conserving surgery was recommended less frequently after MRI, while neoadjuvant chemotherapy followed by modified radical mastectomy was more commonly selected. Management changes occurred predominantly in patients with aggressive tumor biology. Conclusions: Preoperative breast MRI changes staging and treatment decisions in approximately one-third of patients with early breast cancer, particularly among those with aggressive disease features. These findings support the selective use of MRI to optimize individualized treatment planning.