Feasibility of adjuvant chemotherapy with S-1 consisting of a 4-week administration and a two-week rest period in patients with completely resected non-small cell lung cancer

The efficacy of adjuvant chemotherapy with S-1 in patients with completely resected non-small cell lung cancer (NSCLC) has yet to be clarified, and the appropriate schedule for the adjuvant chemotherapy with S-1 remains unknown. A phase II study was conducted to evaluate the feasibility and efficacy of adjuvant chemotherapy with S-1. Patients enrolled in this study were 20-75 years old, had pathological stage IB-IIIA NSCLC, and had received complete resection of NSCLC. S-1 (80 mg/m(2)) was administered orally to the patients for four weeks followed by a two-week rest period (conventional schedule), for a maximum of eight cycles. The primary endpoint was relative dose intensity (RDI), while the secondary endpoints were safety and 1 year of disease-free survival (1y-DFS). Between May 2007 and October 2009, 28 patients were enrolled. The RDI was 63.1% (95% CI, 48.6-77.7). No grade 3 or worse hematological toxicity was observed. Grade 3 non-hematological toxicities were observed in four patients. No grade 4 or worse hematological toxicity was detected. The probability of 1y-DFS was 85.7% (95% CI, 72.8-98.6). In the subgroup analysis, the median RDI of patients over 65 years old was lower compared to the other patients (44.8 vs. 100%; P = 0.013; Mann-Whitney U test). Creatinine clearance (CCr) was lower in the older group, with more grade 2 or 3 non-hematological toxicities in the elderly patients. These results suggest that the conventional schedule of adjuvant chemotherapy with S-1 is not likely to be feasible in older patients with completely resected NSCLC.