Docetaxel and S-1 Followed By Radiation Therapy and Low-Dose Cisplatin in Treating Patients With Stage III or Stage IV Head and Neck Cancer

RATIONALE: Drugs used in chemotherapy, such as docetaxel, S-1, and cisplatin, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Radiation therapy uses high-energy x-rays to kill tumor cells. Giving more than one drug (combination chemotherapy) together with radiation therapy may kill more tumor cells. PURPOSE: This phase II trial is studying how well giving docetaxel and S-1 together with radiation therapy and low-dose cisplatin works in treating patients with stage III or stage IV head and neck cancer.