762P - Prognostic value of metabolic response assessed by 18FDG-PET after induction chemotherapy and after chemoradiotherapy (CRT) in localized esophageal squamous cell carcinoma (ESCC) patients (pts) receiving definite CRT (dCRT)

Abstract

BackgroundAlthough, previous studies reported that metabolic response (MR) assessed by post-CRT 18FDG-PET was associated with survival outcomes in ESCC treated with dCRT, there are few data on the prognostic value of each metabolic response category after induction chemotherapy prior to dCRT and after completion of dCRT. MethodsIn this retrospective study, we evaluated prognostic value of MR after completion of induction chemotherapy and after completion of dCRT in 382 localized ESCC pts receiving induction chemotherapy followed by dCRT from January 2012 to February 2018 at Asan Medical Center in Korea. MR was assessed by EORTC criteria. ResultsMR after induction chemotherapy was significantly associated with progression-free survival (PFS) and overall survival (OS). MR after dCRT was also significantly associated with PFS and OS. MR after either induction chemotherapy or dCRT remained significant after adjusting for other prognostic factors such as clinical TNM stage, sex, and ECOG performance status. Whereas pts achieving mCR/mPR or mPD after either induction chemotherapy or dCRT had good prognosis or poor prognosis, respectively, the prognostic value of mSD was different between post-induction chemotherapy and post-dCRT; it was similar to that of mPR after induction chemotherapy, but it was similar to that of mPD after dCRT. Poorer MR to induction chemotherapy could predict the lack of MR after dCRT; the proportion of mSD/mPD after dCRT was 7.7% in pts with post-induction mCR vs. 16.0% in pts with vs. 40.0% in pts with post-induction mSD vs. 100% in pts with post-induction mPD (p=0.001).Table762PTablePost induction chemotherapyPost-dCRTmetabolic responseNHR for PFS (95% CI)P-valueHR for OS (95% CI)P-valueNHR for PFS (95% CI)P-valueHR for OS (95% CI)P-valuemCR131115011mPR1063.348 (1.221-9.181)0.0192.498 (1.008 - 6.192)0.0481642.182 (1.646-2.892)0.0002.224 (1.694-2.919)0.000mSD106.008 (1.179-20.150)0.0043.640 (1.186-11.171)0.024711.251 (5.088-24.878)0.0009.659 (4.393-21.236)0.000mPD259.209 (9.430-371.767)0.00014.495 (2.676-78.503)0.0023921.768 (14.020-33.797)0.00010.592 (7.016-15.989)0.000diffuse esophagitis31.729 (0.193-15.482)0.6241.103 (0.129-9.453)0.929221.169 (0.651-2.098)0.6011.482 (0.856-2.566)0.160Total1340.0000.0273820.0000.000 ConclusionsMR after induction chemotherapy and after CRT had independent prognostic value with different prognostication between each other in ESCC pts receiving induction chemotherapy followed by dCRT. Legal entity responsible for the studyThe authors. FundingHas not received any funding. DisclosureAll authors have declared no conflicts of interest.