18F FDG PET/CT after Neoadjuvant Chemotherapy and Pathological Responses are Predictive Factors for Disease-Free Survival and Overall Survival in Patients with Locally Advanced Breast Cancer: A Prospective Study

Abstract

We investigated the prognostic value of interim and post-neoadjuvant chemotherapy (NAC) 18F FDG PET/CT and the complete pathological and metabolical response after NAC for disease-free survival (DFS) and overall survival (OS) in patients with locally advanced breast cancer (LABC) receiving NAC. Patients who were decided to receive NAC were evaluated with baseline (PET1), after 2-3 cycles of chemotherapy (interim-PET2), and after NAC-before surgery (PET3) with 18F FDG PET/CT. The primary tumor SUV and the total metabolic tumor volume (MTV) of the primary tumor+axillary lymph nodes were calculated and defined for PET1-2-3 as SUV1-2-3 and MTV1-2-3. We also calculated ??%SUV and ??%MTV for PET1-2 and PET1-3. The relation between parameters and survival was evaluated with Cox regression analysis. Patients were grouped as a complete metabolic response or not (metCR/nonmetCR) according to PET3 and as PCR/non-PCR according to the presence of residual invasive tumor as a result of pathology after NAC. Forty-two patients were analyzed (46.36??10.4 years old). The median follow-up time was 94.3 months. For DFS and OS, only MTV from post-NAC PET/CT was an independent predictor. For MTV3 ??? 2.1 mL vs. > 2.1 mL, 7-year DFS and OS were 81.3% - 50%, (p= 0.038) and 88.2% and 55.6%, (p= 0.042) respectively. Survival was statistically significantly different in the PCR/non-PCR patient groups. There was no difference in DFS between patients with metCR/non-metCR, only between groups for OS (Log-rank). MTV (??? 2.1mL vs. > 2.1mL) obtained from 18F FDG PET/CT after NAC-pre-surgery and complete pathological response might distinguish patients with poor prognosis.