A phase I study of S-1 with concurrent thoracic radiotherapy in elderly patients with localized advanced non-small cell lung cancer

S-1, an oral 5-fluorouracil derivative, is effective against advanced non-small cell lung cancer (NSCLC) with mild toxicity and synergistic effects with radiation in preclinical trials. In this phase I study, we evaluated the dose-limiting toxicity and recommended dose of S-1 for a future phase II study when administered concurrently with thoracic radiation (total dose of 60Gy at 2Gy per daily fraction) in elderly patients (>75 years old) with localized advanced NSCLC. S-1 was administered on days 1-14 and 29-42 at the following dosages: 60, 70, and 80mg/m²/day. Twenty-two previously untreated patients were enrolled in this study. Dose-limiting toxicity included febrile neutropenia, thrombocytopenia, stomatitis, and pneumonitis. One patient had grade 5 radiation pneumonitis. No other patient experienced radiation pneumonitis or esophagitis exceeding grade 2. The recommended dose for S-1 was determined to be 80mg/m²/day, which produced an overall response rate of 75% (n=12). The median progression-free survival time was 11.5 months (95% confidence interval: 7.1-15.8 months) with a median follow-up time of 27.9 months. These results indicate that concurrent treatment with S-1 and thoracic radiation is a feasible option for NSCLC in the elderly. A phase II study is currently under way.