Background: (18)F-FDG-PET is potentially useful for evaluating response to neoadjuvant therapy for esophageal cancer. However, the optimal (18)F-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 ((18)F-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. (18)F-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 SUVmax-DR 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.