IMRT combined with S-1 concurrent chemoradiotherapy in locally advanced nasopharyngeal carcinoma: a prospective phase II study.

Purpose The current standard treatment for locally advanced nasopharyngeal carcinoma (LANPC) is intensity-modulated radiation therapy (IMRT) plus cisplatin concurrent chemoradiotherapy (CCRT). However, this regimen has well-known hematological and gastrointestinal toxicities. Many studies have reported that S-1 was effective in the treatment of multiple solid cancers with mild toxicities. However, knowledge regarding IMRT plus S-1 CCRT in LANPC is lacking. Therefore, we conducted this prospective phase II trial to evaluate the efficacy and safety of this regimen in LANPC. Patients and Methods Eligible patients with histologically confirmed LANPC were enrolled in this study. IMRT was given in 30-32 fractions five times per week. Concurrently, S-1 was administrated twice per day orally based on the body surface area (BSA < 1.25 m2, 30 mg; BSA: 1.25-1.5 m2, 40 mg; BSA > 1.5 m2, 50 mg). The primary endpoints were progression-free survival (PFS) and adverse events. Results From August 1, 2013, to December 15, 2017, 131 patients were enrolled in this study. The distribution of disease stages among the patients was as follows: 21 patients were in stage II (16.0%), 42 patients were in stage III (32.0%), and 68 patients were in stage IV (52.0%). After CCRT, the 3-year PFS, overall survival (OS), local recurrence-free survival (LRFS) and distant metastasis-free survival (DMFS) rates were 87.4%, 95.7%, 94.7%, and 91.5%, respectively. The severity of most toxicities was mild. Approximately two-thirds of patients had no hematological toxicity. Grade 2 hematological toxicities included leukopenia (11.5%), anemia (1.5%), and thrombocytopenia (0.8%). Grade 3 hematological toxicities were rarely observed. Conclusion The results demonstrated that IMRT plus S-1 CCRT was effective with mild toxicity for patients with LANPC.