Feasibility of adjuvant chemotherapy with S-1 plus carboplatin followed by single-agent maintenance therapy with S-1 for completely resected non-small-cell lung cancer: results of the Setouchi Lung Cancer Group Study 1001

Background: This multicenter study evaluated the feasibility of novel adjuvant chemotherapy with S-1 plus carboplatin followed by single-agent, long-term maintenance with S-1 in patients with completely resected stage II–IIIA non-small-cell lung cancer (NSCLC). Methods: Patients received four cycles of S-1 (80 mg/m²/day for 2 weeks, followed by 2 weeks rest) plus carboplatin (area under the curve 5, day 1) followed by S-1 (80 mg/m²/day for 2 weeks, followed by a 1-week rest). Patients unable to continue S-1 plus carboplatin because of severe toxicity converted to single-agent S-1 maintenance. The duration of adjuvant chemotherapy was 10 months in both situations. The primary endpoint was feasibility, defined as the proportion of patients who completed four cycles of S-1 plus carboplatin and single-agent S-1 maintenance for 10 months. The treatment completion rate was determined; treatment was considered feasible if the lower 90% confidence interval (CI) was ≥50%. Results: Eighty-nine patients were enrolled, of whom 87 were eligible and assessable. Seventy-eight patients (89.7%) completed four cycles of S-1 plus carboplatin and 55 (63.2%) completed the following S-1 maintenance therapy for a total of 10 months. The treatment completion rate was 63.2% (90% CI, 54.4–71.2%), indicating feasibility. There were no treatment-related deaths. Grade 3/4 toxicities included neutropenia (13.8%), thrombocytopenia (11.5%), and anorexia (4.6%). The 2-year relapse-free survival rate was 59.8%. Conclusions: We concluded that adjuvant chemotherapy with S-1 plus carboplatin followed by single-agent maintenance therapy with S-1 is feasible and tolerable in patients with completely resected NSCLC. Clinical registration number: UMIN000005041.