RATIONALE: Radiation therapy uses high-energy x-rays to damage tumor cells. Drugs used in chemotherapy use different ways to stop tumor cells from dividing so they stop growing or die. Combining chemotherapy with radiation therapy may kill more tumor cells.

PURPOSE: Phase I trial to study the effectiveness of radiation therapy plus fludarabine in treating patients who have locally advanced cancer of the mouth, pharynx, or larynx.

OBJECTIVES: I. Determine the maximum tolerated dose of fludarabine that can be given during the sixth and seventh weeks of radiotherapy in patients with locally advanced squamous cell carcinoma of the oral cavity, pharynx, or larynx, based on the systemic toxicity of the drug and the acute mucosal reactions in the irradiated fields. II. Document the qualitative and quantitative toxicity of this combination therapy in this patient population.

OUTLINE: This is a dose escalation study of fludarabine. Patients receive radiotherapy on days 1-5 for 7 weeks. Patients receive fludarabine IV on days 1-5 of weeks 6 and 7 of radiotherapy. Fludarabine is administered 3-4 hours prior to daily radiotherapy. Cohorts of 3 patients receive escalating doses of fludarabine until the maximum tolerated dose (MTD) is determined. The MTD is defined as the dose that produces a severe toxicity rate nearest to 20%. Patients are followed every 4 weeks after the completion of treatment until acute reactions have resolved, then every 3 months for 2 years, every 4 months for 1 year, and then every 6 months for 2 years.

PROJECTED ACCRUAL: A maximum of 18 patients will be accrued for this study within 1.5 years.

• Drug: fludarabine phosphate
• Radiation: radiation therapy

DISEASE CHARACTERISTICS: Histologically confirmed squamous cell carcinoma of the oral cavity, pharynx, or larynx for which surgery would result in significant functional impairment Stage III or IV (T3-4 or N2-3) No distant metastases

PATIENT CHARACTERISTICS: Age: 18 and over Performance status: Zubrod 0-2 Life expectancy: At least 6 months Hematopoietic: Granulocyte count at least 1,500/mm3 Platelet count at least 150,000/mm3 Hepatic: Bilirubin no greater than 1.5 mg/dL SGOT less than 4 times upper limit of normal PT/PTT normal Renal: Creatinine no greater than 1.5 mg/dL Other: Not pregnant or nursing Fertile patients must use effective contraception No other concurrent acute illness or infection

PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: No prior chemotherapy Endocrine therapy: Not specified Radiotherapy: No prior radiotherapy Surgery: See Disease Characteristics