Determinants of Response to Neoadjuvant Chemotherapy for Esophageal Cancer Using 18F-fluorodeoxiglucose Positron Emission Tomography (18F-FDG-PET)

Background. F-18-FDG-PET is potentially useful for evaluating response to neoadjuvant therapy for esophageal cancer. However, the optimal F-18-FDG-PET parameter for evaluating the response to therapy and survival has not been established. This study aimed to select the best of the two parameters of fluorodeoxyglucose (F-18-FDG)-positron emission tomography (PET): decreased ratio of maximal standardized uptake (SUVmax-DR) or absolute value of posttreatment SUVmax (post-SUVmax), in predicting response and survival of patients with esophageal cancer who underwent neoadjuvant chemotherapy. Methods. The study subjects were 211 consecutive patients with esophageal cancer who received neoadjuvant chemotherapy followed by surgery. F-18-FDG-PET was performed before and 2-3 weeks after completion of neoadjuvant chemotherapy in assessment with pretreatment SUVmax (pre-SUVmax), post-SUVmax and SUVmax-DR. Results. The mean SUVmax decreased during neoadjuvant chemotherapy from 11.4 to 5.8, and the mean SUVmax-DR was 49.4 %. Both post-SUVmax and SUVmax-DR correlated significantly with pathological response, although neither post-SUVmax nor SUVmax-DR could distinguish pathological complete response from pathological good response. The 5-year survival rate was significantly higher in patients with SUVmaxDR of >50 % than those with <50 % (56.5 vs. 39.6 %, p = 0.0137), and also significantly higher in patients with post-SUVmax of <3.5 than those with >3.5 (62.2 vs. 35.1 %, p < 0.0001). Multivariate analysis identified post-SUVmax value, but not SUVmax-DR, as an independent prognostic factor in patients who underwent neoadjuvant chemotherapy. Conclusions. Post-SUVmax is more useful for predicting survival of patients with esophageal cancer who undergo neoadjuvant therapy followed by surgery, although both SUVmax-DR and post-SUVmax equally correlate with pathological response.