A Phase III Multicenter Randomized Clinical Trial of 60 Gy versus 50 Gy Radiation Dose in Concurrent Chemoradiotherapy for Inoperable Esophageal Squamous Cell Carcinoma

Purpose: In this multicenter phase 3 trial, the efficacy and safety of 60 Gy and 50 Gy doses delivered with modern radiotherapy technology for definitive concurrent chemoradiotherapy (CCRT) in patients with inoperable esophageal squamous cell carcinoma (ESCC) were evaluated. Patients and Methods: Patients with pathologically confirmed stage IIA‒IVA ESCC were randomized 1:1 to receive conventional fractionated 60 Gy or 50 Gy to the tumor and regional lymph nodes. Concurrent weekly chemotherapy (docetaxel 25 mg/m²; cisplatin 25 mg/m²) and two cycles of consolidation chemotherapy (docetaxel 70 mg/m²; cisplatin 25 mg/m² days 1‒3) were administered. Results: A total of 319 patients were analyzed for survival, and the median follow-up was 34.0 months. The 1- and 3-year locoregional progression-free survival (PFS) rates for the 60 Gy group were 75.6% and 49.5% versus 72.1% and 48.4%, respectively, for the 50 Gy group [HR, 1.00; 95% confidence interval (CI), 0.75‒1.35; P ¼ 0.98]. The overall survival rates were 83.7% and 53.1% versus 84.8% and 52.7%, respectively (HR, 0.99; 95% CI, 0.73‒1.35; P ¼ 0.96), whereas the PFS rates were 71.2% and 46.4% versus 65.2% and 46.1%, respectively (HR, 0.97; 95% CI, 0.73‒1.30; P ¼ 0.86). The incidence of grade 3þ radiotherapy pneumonitis was higher in the 60 Gy group (nominal P ¼ 0.03) than in the 50 Gy group. Conclusions: The 60 Gy arm had similar survival endpoints but a higher severe pneumonitis rate compared with the 50 Gy arm. Fifty Gy should be considered as the recommended dose in CCRT for ESCC.