Role of MRI in predicting response to neo-adjuvant systemic therapy (NAST) in breast cancer

Abstract

BACKGROUND AND OBJECTIVES: MRI is generally performed to assess response to Neo-adjuvant systemic therapy (NAST) in breast cancer. OBJECTIVE: To assess role of MRI in determining the probability of having residual disease in patients undergoing NAST. We also evaluated synchronous cancers diagnosed following MRI. METHODS: This is a retrospective study which included all patients who had pre-and post-NAST MRI between June 2014 and December 2019. Data on demographics, tumour characteristics and pathology were collected and analysed. Pre- and post-MRI probability were calculated and depicted on nomograms. RESULTS: The study included 205 patients. Overall pre-MRI probability of having residual disease was 55% (OR:1.2). The post-MRI probability was 78% (95% CI 72–83%; OR:3.5) if MRI showed residual disease and 23% (95% CI 16–31%, OR:0.3) if imaging showed complete response. The absolute benefit was higher in TNBC and HR-HER2. Additional cancers were identified in 8.78% of patients. CONCLUSION: MRI is beneficial in evaluating response to NAST specifically in TNBC and HR-HER2 cancers. Pre- and post-MRI probabilities of residual disease depicted on nomograms are a useful tool for clinicians. MRI can potentially impact the treatment decisions by identification of synchronous cancers.