Efficacy and Safety of Endoscopic Resection Followed by Chemoradiotherapy with S-1 Plus Cisplatin for Esophageal Cancer

Chemoradiotherapy (CRT) with 5-fluorouracil plus cisplatin is commonly used as additional treatment after endoscopic resection (ER) for esophageal squamous cell carcinoma (ESCC); however, metastatic recurrence remains a concern. S-1 is an oral fluoropyrimidine that has shown efficacy in combination with cisplatin and radiotherapy. This single-center, single-arm, exploratory phase II study evaluated the efficacy and safety of ER followed by CRT using S-1 plus cisplatin for superficial ESCC (UMIN000014684). Patients with ESCC diagnosed with stage pT1a-MM or pT1b-SM disease or lymphovascular invasion after ER were enrolled. CRT consisted of two cycles of S-1 administered twice daily on days 1 to 14 and cisplatin (70 mg/m²) on day 1 every 4 weeks, in conjunction with radiotherapy (40.0–41.4 Gy). The primary endpoint was 3-year overall survival (OS). Progression-free survival and adverse events were also examined. Thirty-eight patients underwent CRT with S-1 plus cisplatin. The 3-year OS and progression-free survival rates were 94.7