LAUSR

BACKGROUND & AIMS Esophagectomy is the standard treatment for stage I esophageal squamous cell carcinoma (ESCC). We conducted a single-arm prospective study to confirm the efficacy and safety of selective chemoradiotherapy (CRT) based on findings from endoscopic resection (ER). METHODS We performed a prospective study of patients with T1b (SM1-2) N0M0 thoracic ESCC; from December 2006 through July 2012, 176 patients underwent ER. Based on the findings from ER, patients received: no additional treatment, for patients with pT1a tumors with a negative resection margin and no lymphovascular invasion (Group A); prophylactic CRT with 41.4 Gy delivered to locoregional lymph nodes, for patients with pT1b tumors with a negative resection margin or pT1a tumors with lymphovascular invasion (Group B); or definitive CRT (50.4 Gy) with a 9-Gy boost to the primary site, for patients with a positive vertical resection margin (Group C). Chemotherapy comprised 5-fluorouracil and cisplatin. The primary endpoint was 3-year overall survival (OS) in Group B, and the key secondary endpoint was 3-year OS for all patients. If lower limits of 90% CIs for the primary and key secondary endpoints exceeded the 80% threshold, the efficacy of combined ER and selective CRT was confirmed. RESULTS Based on the results from pathology analysis, 74, 87, and 15 patients were categorized into Groups A, B, and C, respectively. The 3-year OS rates were 90.7% for Group B (90% CI, 84.0%-94.7%) and 92.6% in all patients (90% CI, 88.5%-95.2%). CONCLUSIONS In a prospective study of patients with T1b (SM1-2) N0M0 thoracic ESCC, we confirmed the efficacy of the combination of ER and selective CRT. Efficacy is comparable to that of surgery, and the combination of ER and selective CRT should be considered as a minimally invasive treatment option. Clinical trial registration no: UMIN-CTR (UMIN000000553).