This study is a single-arm, multicenter clinical trial evaluating the efficacy and safety of radiotherapy combined with TAS-102 monotherapy in elderly patients with locally advanced esophageal cancer.

Treatment Phase: The treatment phase is divided into a Phase I stage and a Phase II stage. The Phase I stage aims to explore the maximum tolerated dose (MTD) of TAS-102 in elderly esophageal cancer patients. A total of 9 subjects were enrolled, and the dose was escalated from 30 mg/m² in 5 mg/m² increments up to 40 mg/m². The MTD was defined as the highest drug dose at which no dose-limiting toxicity (DLT) was observed in more than 40% of treated patients during the first two weeks of combined radiotherapy and TAS-102 administration. The Phase II stage aims to investigate the efficacy of radiotherapy combined with TAS-102 at the MTD in elderly esophageal cancer patients, with 36 subjects enrolled.

Consolidation Phase: Following the treatment phase, subjects had a 3-4 week rest period. This was followed by consolidation therapy with TAS-102 monotherapy at a dose of 35 mg/m², administered twice daily on days 1-5 of a 28-day cycle for two cycles.

Subsequently, patients entered the efficacy and safety follow-up phase until the study endpoints were reached or after a full 2-year follow-up period.

Inclusion Criteria:

• Patients must have newly confirmed histologically or cytologically diagnosed esophageal squamous cell carcinoma.
• Age between 65 and 85 years.
• Esophageal cancer staged as IIB to IVB according to the 8th edition AJCC staging system (including IVB with supraclavicular or celiac lymph node metastasis, but excluding IVB with other distant metastases).
• ECOG performance status of 0 or 1.
• No history of esophageal perforation, active esophageal bleeding, or significant invasion of the trachea or major thoracic blood vessels.
• No prior anticancer therapy such as radiotherapy or chemotherapy. Adequate bone marrow function: hemoglobin ≥9 g/dL, white blood cells ≥3.0×10⁹/L, neutrophils ≥1.5×10⁹/L, platelets ≥100×10⁹/L.
• Adequate liver and kidney function: serum creatinine (Scr) ≤1.5×ULN, total bilirubin ≤1.5×ULN, ALT and AST ≤2.5×ULN.
• No history of interstitial lung disease.
• Forced expiratory volume (FEV1) ≥0.8 liters.
• Signed informed consent form before study initiation.

Exclusion Criteria:

• Patients with hematogenous metastasis or distant lymph node metastasis (except supraclavicular or celiac lymph node metastasis), multiple esophageal cancer lesions, or malignant pleural/pericardial effusion.
• History of radiotherapy, chemotherapy, or surgery targeting the primary tumor or lymph nodes.
• Tracheoesophageal fistula, invasion of the trachea or main bronchi by the primary tumor, deep esophageal ulcer, or hematemesis.
• Severe comorbidities such as active infection, cardiovascular disease, or pulmonary disease.
• History of other malignancies except adequately treated non-melanoma skin cancer.
• Participation in another clinical trial within the past 30 days.
• Any other condition deemed by the investigator to preclude participation in the study.