Feasibility of endoscopic response evaluation after induction chemotherapy for determining treatment strategies in esophageal cancer: a post hoc analysis of the CROC trial.

内容摘要

The CROC trial assessed a response-guided approach using endoscopic criteria to identify candidates for definitive chemoradiotherapy (dCRT) as an alternative to surgery for resectable thoracic esophageal squamous cell carcinoma (ESCC). Precise evaluation of treatment response following induction chemotherapy is essential for determining curative strategies. This post hoc analysis of the CROC trial investigated the interobserver concordance of endoscopic response evaluation and its clinical implications. Eighty-seven patients with resectable thoracic ESCC underwent three cycles of induction chemotherapy with docetaxel, cisplatin, and 5-fluorouracil. Endoscopic responses were centrally reviewed by three expert oncologists and categorized as remarkable response (RR), limited partial response, or poor response. Patients were classified as having definitive RR, definitive non-RR, or uncertain response based on reviewer agreement. A comprehensive consensus was achieved, with 51.7% (45/87) and 31.0% (27/87) of patients categorized as definitive RR and definitive non-RR, respectively, whereas 17.2% (15/87) were classified as uncertain response. Patients with definitive RR and uncertain response exhibited high complete response (CR) rates to dCRT at 89.7% (35/39) and 90.9% (10/11), respectively, whereas those with definitive non-RR demonstrated a lower CR rate of 25.0% (1/4). 18F-fluorodeoxyglucose positron emission tomography revealed a progressive decrease in maximum standardized uptake value in the RR and uncertain response groups compared with the non-RR group. Among the surgical cases with definitive RR, the positive predictive value for pathological findings was 83.3% (5/6). High interobserver concordance supports standardizing endoscopic evaluation criteria. Furthermore, an uncertain response may indicate the suitability of dCRT because of favorable outcomes.