Abstract PD15-08: PD15-08 Brazilian Randomized Study - BREAST-MRI Trial - Impact of Preoperative Magnetic Resonance in the Evaluation for Breast Cancer Conservative Surgery: Local recurrence and surgical outcomes

Abstract Introduction: Breast magnetic resonance imaging (MRI) has high sensitivity in detecting invasive neoplasms. However, controversy remains as to whether preoperative staging with breast MRI impacts surgical outcomes and local recurrence. Materials and Methods: BREAST-MRI is a randomized, open-label trial including female breast cancer patients older than 18 years old, with stage 0-III disease, eligible for BCS. We performed a 1:1 stratified randomization by breast density according to ACR-BIRADS to divide patients into two groups; one in which preoperative MRI was used and the control group where the MRI was not used. The primary outcome was local relapse-free survival (LR). Secondary outcomes were overall survival (OS), repeat operation, and the proportion of patients whose surgical management was modified to mastectomy. Results: 524 were randomized, 257 included in the MRI group, and 267 in the control group. The baseline characteristics were similar between groups, except for chemotherapy use (table 1). The survival analysis showed a 6-year local recurrence-free survival was 99.2% in MRI group versus 98.9% in the control group, p=0.702, overall survival of 95.3% in the MRI group versus 96.3% in the control group, p=0.481. No difference was found in reoperation rates, 22 (8.7%) in the MRI group versus 23 (8.7%) in the control group (p= 0.85)(table2). Surgical management changed in 21 ipsilateral breasts in the MRI group; 21 (8.3%) had mastectomies versus 1 in the control group (p< 0.01). Conclusion: Preoperative MRI evaluation increased the mastectomy rates by 8%. The use of preoperative MRI did not influence local relapse-free survival, overall survival, or reoperation rates Keywords: breast magnetic resonance imaging; breast cancer; conservative surgery; MRI accuracy, surgical outcomes, randomized clinical trial Citation Format: Bruna S. Mota, Yedda N. Reis, Nestor Barros, Natalia Cardoso, Rosa s. Mota, Carlos Shimizu, Tatiana Tucunduva, Rodrigo Gonçalves, Maira T. Doria, Vera Ferreira, Marcos Ricci, Angela Trinconi, Rachel Riera, Edmund C. Baracat, José Maria Soares Jr, Jose Roberto Filassi. PD15-08 Brazilian Randomized Study - BREAST-MRI Trial - Impact of Preoperative Magnetic Resonance in the Evaluation for Breast Cancer Conservative Surgery: Local recurrence and surgical outcomes [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD15-08.