[Phase I study of concurrent radiotherapy with TS-1 and vitamin A (TAR Therapy) for head and neck cancer].

The triple combination of 5-fluorouracil (5-FU), vitamin A and radiation (FAR therapy) has been effectively used to treat head and neck cancer. The biological anti-tumor effect of 5-FU depends on the activity of its metabolizing enzyme, dihydropyrimidine dehydrogenase (DPD). TS-1 is a novel oral DPD inhibitory fluoropyrimidine (DIF). To improve the anti-tumor effect of FAR therapy, we have applied TS-1 in place of 5-FU injection in the combination of Vitamin A and radiation (TAR therapy). In this study, we have examined the appropriate duration of TS-1 medication and the clinical efficacy and safety of TAR therapy. TS-1 was administered orally at a dose of 65 mg/m2 twice a day. Vitamin A (Retinol Palmitate: 50,000 U/day) was administered intra-musculary on each day of radiation. Radiation was given (1.5-2 Gy/day: 5 days/week) for 30-40 Gy. The levels were divided according to the length of TS-1 application as follows: level 1, 2 weeks; level 2, 3 weeks; level 4, 4 weeks. Grade 4 toxicity of anorexia was observed in one case of level 3. We decided that level 2 (3 weeks of TS-1 administration) was the appropriate length of TS-1 application. TAR therapy is a useful concurrent chemo-radiotherapy which might improve the response rate and QOL of patients with HNSCC.