Adjuvant chemotherapy with S-1 after curative chemoradiotherapy in patients with locoregionally advanced squamous cell carcinoma of the head and neck: Reanalysis of the ACTS-HNC study.

BACKGROUND:Chemoradiotherapy (CRT) has improved organ preservation or overall survival (OS) of locoregionally advanced head and neck squamous cell cancer (LAHNSCC), but in clinical trials of conventional CRT, increasing CRT intensity has not been shown to improve OS. In the Adjuvant ChemoTherapy with S-1 after curative treatment in patients with Head and Neck Cancer (ACTS-HNC) phase III study, OS of curative locoregional treatments improved more with adjuvant chemotherapy with S-1 (tegafur gimeracil oteracil potassium) than with tegafur/uracil (UFT). ACTS HNC study showed the significant efficacy of S-1 after curative radiotherapy in sub-analysis. We explored the efficacy of S-1 after curative CRT in a subset of patients from the ACTS-HNC study. METHODS:Patients with stage III, IVA, or IVB LAHNSCC were enrolled in this study to evaluate the efficacy of S-1 compared with UFT as adjuvant chemotherapy after curative CRT in the ACTS-HNC study. Patients received S-1 at 80-120 mg/day in two divided doses for 2 weeks, followed by a 1-week rest, or UFT 300 or 400 mg/day in two or three divided doses daily, for 1 year. The endpoints were OS, disease-free survival, locoregional relapse-free survival, distant metastasis-free survival (DMFS), and post-locoregional relapse survival. RESULTS:One hundred eighty patients (S-1, n = 87; UFT, n = 93) were included in this study. Clinical characteristics of the S-1 and UFT arms were similar. S-1 after CRT significantly improved OS (hazard ratio [HR], 0.46; 95% confidence interval [CI], 0.22-0.93) and DMFS (HR, 0.50; 95% CI, 0.26-0.97) compared with UFT. CONCLUSION:As adjuvant chemotherapy, S-1 demonstrated better efficacy for OS and DMFS than UFT in patients with LAHNSCC after curative CRT and may be considered a treatment option following curative CRT. For this study was not preplanned in the ACTS-HNC study, the results is hypothesis generating but not definitive.