S9908: Glutamine in Treating Mucositis Caused by Radiation Therapy in Patients With Newly Diagnosed Cancer of the Mouth or Throat

DISEASE CHARACTERISTICS: * Newly diagnosed, previously untreated squamous cell cancer of the oral cavity or oropharynx (T1-T4, any N, M0) * Must be scheduled to receive high-dose radiotherapy * Not concurrently receiving or planning to receive treatment on any other Southwest Oncology Group protocol PATIENT CHARACTERISTICS: Age: * 18 to 90 Performance status: * Zubrod 0-2 Life expectancy: * Not specified Hematopoietic: * Not specified Hepatic: * Not specified Renal: * Not specified Other: * No other malignancy within the past 5 years except adequately treated basal cell or squamous cell skin cancer, carcinoma in situ of the cervix, or stage I or II cancer currently in complete remission * Not pregnant or nursing * Fertile patients must use effective contraception PRIOR CONCURRENT THERAPY: Biologic therapy: * Not specified Chemotherapy: * No prior chemotherapy * Concurrent cisplatin, carboplatin, or fluorouracil allowed * No other concurrent chemotherapy during study and for at least 3 weeks after study radiotherapy Endocrine therapy: * Not specified Radiotherapy: * See Disease Characteristics Surgery: * Not specified Other: * No concurrent amifostine during and for 2 weeks after study radiotherapy