Post-Chemoradiotherapy Fdg Pet With Qualitative Interpretation Criteria For Outcome Stratification In Esophageal Squamous Cell Carcinoma

ObjectivesPost-chemoradiotherapy (CRT) FDG PET is a useful prognosticator of esophageal cancer. However, debate on the diverse criteria of previous publications preclude worldwide multi-center comparisons, and even a universal practice guide. We aimed to validate a simple qualitative interpretation criterion of post-CRT FDG PET for outcome stratification and compare it with other criteria.MethodsThe post-CRT FDG PET of 114 patients with esophageal squamous cell carcinoma (ESCC) were independently interpreted using a qualitative 4-point scale (Qual(4ps)) that identified focal esophageal FDG uptake greater than liver uptake as residual tumor. Cohen's K coefficient (K) was used to measure interobserver agreement of Qual(4ps). The Kaplan-Meier method and Cox proportional hazards regression analyses were used for survival analysis. Other criteria included a different qualitative approach (Qual(BK)), maximal standardized uptake values (SUVmax3.4, SUVmax2.5), relative change of SUVmax, between pre- and post-CRT FDG PET (Delta SUVmax), mean standardized uptake values (SUVmax) metabolic volume (MV) and total lesion glycolysis (TLG).ResultsOverall interobserver agreement on the Qual(4ps) criterion was excellent (K: 0.95). Except the Qual(BK), SUVmax2.5, and TLG, all the other criteria were significant predictors for overall survival (OS). Multivariable analysis showed only Qual(4ps) (HR: 15.41; P = 0.005) and AJCC stage (HR: 2.47; P = 0.007) were significant independent variables. The 2-year OS rates of Qual(4ps)(-) patients undergoing CRT alone (68.4%) and patients undergoing trimodality therapy (62.5%) were not significant different, but the 2-year OS rates of Qual(4ps)(+) patients undergoing CRT alone (10.0%) were significantly lower than in patients undergoing trimodality therapy (42.1%).ConclusionsThe Qual(4ps) criterion is reproducible for assessing the response of ESCC to CRT, and valuable for predicting survival. It may add value to response-adapted treatment for ESCC patients, and help to decide whether surgery is warranted after CRT.