Role of Tc99m-Sestamibi scintimammography in assessing response to neoadjuvant chemotherapy in patients with locally advanced breast cancer

INTRODUCTION: Neoadjuvant chemotherapy (NACT) is an essential part of multi-disciplinary management of locally advanced breast cancer (LABC). In this study, we aimed at evaluating the role of Tc99m-Sestamibi scinti-mammography in assessing response to NACT in patients with LABC. MATERIALS AND METHODS: A total of 42 patients of histologically proven LABC were enrolled in this prospective study. Imaging was performed according to pre-defined protocol at 10 min and 4 h after injection of tracer before the start of chemotherapy, 48 h after start of chemotherapy and at the end of chemotherapy. Quantitative parameters were obtained by calculating the ratio of activity in a region of interest (ROI) drawn over the tumor and the same sized ROI drawn in corresponding location in contra lateral breast. RESULTS: At the end of chemotherapy, 6 patients achieved complete response, 25 achieved partial response, 11 had stable disease. Various retention indices calculated at baseline, 48 h after first cycle of NACT, and at the end of chemotherapy showed statistically significant difference in responders and non-responders. By using 84.05 as cut-off point for retention index (RI) of tumor calculated 48 h after first cycle of NACT (RI 2) the positive predictive value and negative predictive value, were found to be 41.9% and 72.7% respectively in differentiating responders from non-responders. CONCLUSION: Early response assessment in patients with LABC to NACT with Tc99m-Sestamibi scintimammography is feasible and if confirmed by further studies can find routine clinical application in differentiating responders from non-responders.