Adding oral S-1 chemotherapy to radiotherapy can improve outcomes in elderly patients with inoperable esophageal squamous cell carcinoma (ESCC), according to phase 3 data presented at the 2022 ASTRO Annual Meeting.  

Patients had improvements in overall survival (OS) and progression-free survival (PFS) if they received chemoradiotherapy rather than radiotherapy alone.

This phase 3 study included 330 patients with inoperable ESCC who were 70 years of age or older at baseline. They were randomly assigned to S-1-based chemoradiotherapy followed by S-1 monotherapy (n=184) or radiotherapy alone (n=146). Baseline characteristics were comparable between the arms.


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In both arms, patients received simultaneous integrated boost radiotherapy (59.92 Gy/50.4 Gy) in 28 daily fractions given using intensity-modulated radiotherapy or volumetric modulated arc therapy. Patients in the chemoradiotherapy arm received S-1 (40-60 mg/m2) concurrently with radiotherapy and 4-8 weeks later, for up to four 3-week cycles at the same dose.

OS and PFS were superior with chemoradiotherapy in the intent-to-treat population and the per-protocol population.

In the intention-to-treat population, the 3-year OS rate was 46.2% with chemoradiotherapy and 33.9% with radiotherapy alone (hazard ratio [HR], 0.73; 95% CI, 0.56-0.96; P =.024). The 3-year PFS rate was 37.3% for chemoradiotherapy and 27.9% for radiotherapy alone (HR, 0.76; 95% CI, 0.58-0.98; P =.036). 

In the per-protocol population, the 3-year OS rate was 56.8% in the chemoradiotherapy arm and 35.7% in the radiotherapy arm (HR, 0.52; 95% CI, 0.35-0.76; P =.001). The 3-year PFS rate was 47.1% and 29.1%, respectively (HR, 0.56; 95% CI, 0.39-0.80; P =.001).

There were no significant differences in grade 3 or higher adverse events (AEs). There were 5 fatal AEs in each arm. Fatal AEs in the radiotherapy arm were pneumonitis (n=4) and myelosuppression (n=1). Fatal AEs in the chemoradiotherapy arm were pneumonitis (n=3) and fever (n=2).

Reference

Wang X, Han W, Zhang W, et al. Effectiveness of S-1–based chemoradiotherapy and S-1 consolidation in elderly patients with esophageal squamous cell carcinoma: A multicenter randomized phase III clinical trial. ASTRO 2022. October 23-26, 2022. Abstract 118.