Abstract Background: The use of magnetic resonance imaging (MRI) in patients with breast cancer before surgery has been a subject of ongoing debate and discussion. The role of MRI as a preoperative tool to guide surgical decision-making remains controversial. Some studies suggest that MRI may improve the detection of additional tumors or assess the extent of disease, while others discuss that it may lead to increased false-positive findings and unnecessary interventions. The potential benefits and potential harms of incorporating MRI into the preoperative assessment of breast cancer patients continue to be topics of research and clinical interest. Clarifying the impact of preoperative MRI on surgical outcomes is crucial to inform evidence-based practices and optimize patient care. Until present, there is no pooled analyses from randomized clinical trials perspective of the clinical impact regarding the routine use of MRI. Objectives: This study aims to conduct metanalysis of randomized controlled trials (RCT) to investigate the association between preoperative MRI and surgical outcomes in women with newly diagnosed invasive breast cancer, providing evidence-based recommendations for clinical practice. Methods: A comprehensive search of electronic databases including PubMed, Medline, Embase, Ovid, Cochrane Library, and Web of Science was conducted by three independent researchers from inception to May 2023. The inclusion and exclusion criteria were based on Cochrane's principles. Relevant data from eligible studies were extracted. A systematic evaluation and meta-analysis were performed using the fixed-effects model to estimate the pooled risk ratio (RR) and 95% CI. Results: Out of 21 studies found, 6 were RCTs and 15 observational comparative studies. The results showed that in RCT preoperative MRI significantly reduce the rate of immediate breast conservative surgery (RR=0.94, 95%CI 0.91~0.96, I2=0%) and increase the mastectomy rate (RR=1.88, 95%CI 1.48~2.38, I2=86%). There wasn’t any change in reoperations rates (RR=0,87, 95%CI 0.71~1.07, I2=72%). Only 1 trial reported data on survival, showing no difference between groups. Conclusion: From RCT standpoint, the evidence suggests that preoperative MRI for newly diagnosed invasive breast cancer may not be beneficial to the patients by increasing rate of mastectomy with no survival benefit and that should be considered when offering as a routine practice to patients with breast cancer before surgery. Forest plot of mastectomy as an outcome Forest plot of re-operation as an outcome Citation Format: Andre Mattar, Andressa Amorim, Evandro Mateus, Fabio Bagnoli, Felipe Zerwes, Francisco Pimentel Cavalcante, Guilherme Novita, Lincon Mori, Marcelo Madeira, Marina Diogenes, Marcelo Antonini, Lucas Okumura. PROMISE Study: Pre-Operatory MRI is not Effective. A Systematic review of impact of magnetic resonance imaging on surgery-decision and clinical outcomes in women with breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-27-03.