Multicenter phase II trial of preoperative chemoradiotherapy with S-1 for locally advanced oral squamous cell carcinoma

We evaluated whether preoperative chemotherapy with S-1 and concurrent radiotherapy is feasible and efficacious in the treatment of advanced oral squamous cell carcinoma. Participants comprised 39 patients with oral carcinoma (stage III, n = 15; stage IVA, n = 24). All patients received a total radiation dose of 40 Gy, in once-daily 2-Gy fractions, and received S-1 at 65 mg/m(2)/day for 5 consecutive days, over 4 consecutive weeks with concurrent radiotherapy. Hematological toxicity was mild and reversible. The most common non-hematological toxicity was grade 3 mucositis, but this was transient and tolerable. Radical surgery was performed for 37 patients, with the remaining 2 patients declining the surgery. Postoperatively, local failure developed in 1 patient, and neck failure in 2 patients. Distant metastases were identified in 4 patients. At a median follow-up of 38.0 months (range 23-88 months), locoregional control, disease-specific survival, and overall survival rates at 3 years were 91.5, 83.8, and 83.8 %, respectively. Concurrent administration of S-1 and radiotherapy combined with surgery offers a well-tolerated method of successfully treating advanced oral squamous cell carcinoma. The locoregional control rate remains high even at 3 years of follow-up, and no serious adverse effects have been encountered.