Concurrent chemoradiotherapy with S-1 compared with concurrent chemoradiotherapy with docetaxel and cisplatin for locally advanced esophageal squamous cell carcinoma.

BACKGROUND: This retrospective study was to assess and compare the toxicity and efficacy of concurrent chemoradiotherapy (CCRT) with S-1 or docetaxel and cisplatin in patients with locally advanced esophageal squamous cell carcinoma (ESCC). METHODS: Patients with locally advanced ESCC who received CCRT with S-1 (70 mg/m2 twice daily on days 1-14, every 3 weeks for 2 cycles, S-1 group) or docetaxel (25 mg/m2) and cisplatin (25 mg/m2) on day 1 weekly (DP group) between 2014 and 2016 were retrospectively analyzed. Radiotherapy was delivered in 1.8-2.0 Gy per fraction to a total dose of 50-60 Gy. Treatment-related toxicities (Common Terminology Criteria for Adverse Events version 4.0), response rate, and survival outcomes were compared between groups. RESULTS: A total of 175 patients were included in this study (72 in the S-1 group and 103 in the DP group). Baseline characteristics were well balanced between the two groups. The incidence of grade 3-4 adverse events were significantly lower in the S-1 group than that of the DP group (22.2% vs. 45.6%, p = 0.002). In the DP group, elderly patients (> 60 years) had a significantly higher rate of grade 3-4 adverse events than younger patients (58.1% vs. 31.3%, p = 0.01). The objective overall response rate (complete response + partial response) was 68.1% in the S-1 group, and 73.8% the DP group (p = 0.497). The 3-year overall survival was 34.7% in the S-1 group, and 38.8% in the DP group (p = 0.422). The 3-year progression free survival in the DP group was higher than that in the S-1 group but without significant difference (33.0% vs. 25.0%, p = 0.275). CONCLUSION: CCRT with S-1 is not inferior to CCRT with docetaxel and cisplatin and is better tolerated in in elderly patients with locally advanced ESCC.