Cytochlor and Tetrahydrouridine as Radiosensitizers and Cisplatin Combined With Radiation Therapy in Treating Patients With Advanced Squamous Cell Carcinoma of the Oral Cavity (Mouth) or Oropharynx (Throat)

RATIONALE: Radiation therapy uses high-energy x-rays to damage tumor cells. Radiosensitizing drugs, such as cytochlor and tetrahydrouridine, may make tumor cells more sensitive to radiation therapy. Drugs used in chemotherapy, such as cisplatin work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Combining radiosensitizers with chemotherapy and radiation therapy may kill more tumor cells. PURPOSE: This phase I trial is studying the side effects and best dose of cytochlor when given together with tetrahydrouridine, cisplatin and radiation therapy in treating patients with advanced squamous cell carcinoma of the oral cavity (mouth) or oropharynx (throat).