S-1 chemotherapy and intensity-modulated radiotherapy after D1/D2 lymph node dissection in patients with node-positive gastric cancer: a phase I/II study

BACKGROUND: This phase I/II clinical trial investigated S-1 administered with intensity-modulated radiotherapy (IMRT) as adjuvant therapy for node-positive gastric cancer. Patients had undergone radical resection and D1/D2 lymph node dissection. METHODS: In phase I, patients received adjuvant chemoradiotherapy of IMRT (45 Gy in 25 fractions) with concurrent S-1 administered on a dose-escalation schedule to determine the recommended dose (RD). In phase II, the safety and efficacy of the RD of S-1 combined with IMRT were assessed. RESULTS: We consecutively enrolled 73 patients (56 men; median age, 53 years; range, 29–73 years) and the phase I portion of the study included 27 patients. The RD of S-1 administered concomitantly with IMRT was 80 mg m(−2) day(−1) orally, twice daily. The phase II analysis included 52 patients (46 new patients plus 6 from phase I). 8 patients (15.4%) developed grade 3 or 4 toxicities. There were 21 recurrence events and 15 deaths (1 bowel obstruction, 14 gastric cancer). Three-year disease-free survival and overall survival were 62.2% (95% confidence interval (CI), 48.5–75.9) and 70.0% (95% CI, 56.3–83.7), respectively. The median time to recurrence was 17.5 months (range, 3.8–42.0). The median time from recurrence to death was 7.0 months (range, 1.5–28.7). CONCLUSIONS: S-1 combined with IMRT adjuvant chemoradiotherapy is safe and efficacious for advanced gastric cancer.