Concurrent chemoradiotherapy (CCRT) with 5-florouracil (5-Fu) and cisplatin (CDDP) are often associated with significant incidence of toxicities in elderly esophageal cancer patients. The compound drug S-1, composed of a combination of tegafur-gimeracil-oteracil has been widely used in a variety of solid tumors, including esophageal cancer. Preclinical studies indicate that S-1 shows far superior anti-tumor activities than 5-Fu and enhances the sensitivity of cancer cells to the effects of radiotherapy (RT). Trial design: This trial was designed as a prospective, single center, non-randomize, phase II study. The primary end point was the response rate which was assessed according to RECIST system 3-4 weeks after the completion of CCRT. The secondary end points were survival outcomes including OS and PFS and treatment-related toxicity. The study was designed to measure an objective response rate (CR plus PR) of 85% compared with a minimal, clinically meaningful response rate of 70%. Upon employing an &agr;= 0.05 and a &bgr; = 0.20, the target number of patients required to achieve this level of significance was 20 cases. Considering some deviant cases, the preplanned number of enrolled patients was set to 22 patients. OS was determined as the time between the first day of CCRT and the last follow-up or the date of death. PFS was calculated from the date of treatment initiation to the date of documented failure or the date of the last follow-up for those remaining. Toxicities were evaluated according to the common toxicity criteria for adverse events version 3.0 (CTCAE v3.0). Preplanned concurrent S-1 (70mg/m2/day) was given on Days 1-14, every 3 weeks. Radiotherapy was delivered with a daily fraction of 1.8-2.0Gy to a total radiation dose of 54.0-60.0Gy. After CCRT, maintenance S-1 was repeated up to four cycles. Patients were regarded eligible according to the following criteria: i) ages ≥ 70 years; ii) cytologically or histologically confirmed esophageal carcinoma; iii) Eastern Cooperative Oncology Group (ECOG) PS of 0 or 1; iv) no evidence of severe organ dysfunction; v) expectancy life >=3 months; vi) at least one measurable lesion on CT, MRI or esophageal barium exam; and vii) no cancer treatments prior to enrollment. Clinical trial identification: NCT02716688. Legal entity responsible for the study: N/A