PET scanning and patient reported dysphagia before and after chemotherapy (CT) for prediction of pathological response after CT and chemoradiotherapy (CRT) in patients with locally advanced esophageal cancer (EC): A multicenter phase ll trial of the Swiss

Abstract

4587 Background: Only responding patients (pts) ultimately benefit from preoperative therapy for locally advanced EC. To predict response quality after CRT and detect non-responders earlier, we evaluated changes from baseline in FDG uptake by PET scans and patient reported dysphagia after two cycles of CT. Methods: Pts with resectable, locally advanced squamous cell carcinoma or adenocarcinoma of the esophagus were treated with 2 cycles of CT with docetaxel/cisplatin (DC) q3w followed by CRT (DC weekly x5 with concomitant 45 Gy RT) and surgery. PET imaging using [F]-deoxyglucose (FDG) uptake and subjective dysphagia assessment using a quality of life module specific to EC (EORTC QLQ-OES24) were performed at baseline and after the 2nd cycle of CT. 40% decrease of FDG uptake was prospectively hypothesized to be an early predictor for a pathological complete remission (tumor regression grade 1, TRG) and subtotal regression (TRG 2) after the CRT. The predictive value of improvement in dysphagia was tested by analysis of covariance with baseline dysphagia as covariate. Results: Out of included 66 pts, 56 completed preoperative therapy and surgery. Dysphagia scores (range 0–100) were available in 51 pts, mean changes were 14 (n=13), 12 (n=16) and 12 (n=22) for pts with TRG 1, 2 or >2, respectively, lacking any significance. 44 pts had two PET scans (5: centers not participating, 3: no FDG-uptake at baseline, 4: second scan too late or not done). Mean FDG-decrease was 49% (n=7), 44% (n=17), 15% (n=20) for pts with TRG 1, 2 or >2, respectively. Less than 40% reduction in FDG uptake predicted non-response (TRG>2) with sensitivity 70%, specificity 50%, negative predictive value 70% and positive predictive value 50%. FDG- uptake reduction indicated reduced risk of TRG>2 in a logistic regression model (p<0.01, 95%-CI 2–273). Conclusions: Decreased FDG uptake in sequential PET scans strongly correlates with tumor response, but is not accurate enough to early identify non- responders. Early improvement of dysphagia after 2 cycles CT did not predict TRG after CRT. No significant financial relationships to disclose.