Single‐Agent Versus Double‐Agent Chemotherapy in Concurrent Chemoradiotherapy for Esophageal Squamous Cell Carcinoma: Prospective, Randomized, Multicenter Phase II Clinical Trial

LESSONS LEARNED The efficacy of single-agent chemotherapy was not significantly different from that of double-agent chemotherapy in concurrent chemoradiotherapy for inoperable esophageal squamous cell carcinoma. Single-agent concurrent chemoradiotherapy had lower gastrointestinal and hematologic toxicity. Overall survival and progression-free survival were not significantly different between single- and double-agent concurrent chemoradiotherapy. BACKGROUND This multicenter, randomized, phase II trial aimed to compare the efficacy and safety of single-agent concurrent chemoradiotherapy using the oral fluoropyrimidine S-1 with those of double-agent concurrent chemoradiotherapy using S-1 and cisplatin in patients with inoperable esophageal squamous cell carcinoma. METHODS Patients with inoperable esophageal squamous cell carcinoma (clinical stages I to III) were randomly allocated to the single-agent group (S-1) or the double-agent group (S-1/cisplatin). The concurrent intensity-modulated radiation therapy plan was similar for both groups: planning target volume 1.8 Gy/f*30-33f and planning gross target volume of 2 Gy/f*30-33f. The primary outcome measure was the endoscopic complete response rate. RESULTS Of the 105 patients randomized, 89 were assessable. The endoscopic complete response rate was 46.9% (23/49) in the single-agent group and 52.5% (21/40) in double-agent group. The median progression-free survival within a median follow-up of 23 months was 20 and 21 months, respectively. The median overall survival was 26 months and not reached, respectively. Grade 3 hematological toxicities occurred in 4.1% and 27.5% of the patients in the single- and the double-agent group, respectively. CONCLUSION Single-agent chemotherapy in concurrent chemoradiotherapy for inoperable esophageal squamous cell carcinoma has good efficacy and safety, thus warranting a phase III trial.