A phase II study of S-1 with concurrent radiotherapy in elderly patients with esophageal cancer

Concurrent chemoradiotherapy (CCRT) using conventional platinum-based doublets are often associated with significant incidence of toxic effects in elderly patients with esophageal cancer. We previously reported a phase I trial of CCRT using S-1, an oral 5-fluorouracil derivative, which yielded well safe and active outcomes.

Patients with histologically confirmed esophageal cancer, who were age of 70 years or older with performance status (PS) score of 0-2 or age of 66 to 69 with PS score of 2, were eligible for this Phase II trial. Radiotherapy was delivered in 1.8 Gy per fraction to a total dose of 54 Gy. Concurrently, S-1 was administered at 70 mg/m² on days 1-14 and 29-42. The primary end point was 2-year overall survival rate.

Thirty patients were enrolled, and 28 patients completed the full course of radiotherapy. No grade 4 toxicity or treatment-related death occurred. The grade 3 toxicities included esophagitis (16.7%), leucopoenia (13.3%), neutropenia (10%), anaemia (3.3%), pneumonitis (3.3%) and fatigue (3.3%). The median progression-free survival time and median survival time was 19 and 24 months, respectively. The 2-year overall survival rate was 45.1%, which exceeded the predefined threshold of 2-year OS 35% and met the primary end point of the study.

The results suggest that CCRT using S-1 is effective with mild toxicity in elderly patients with esophageal cancer. A phase III trial is needed to further evaluate this regimen.