Fruit and Vegetable Extracts in Treating Patients With Stage I-IV, Stage IVA/IVB Head and Neck Cancer

DISEASE CHARACTERISTICS: * Curatively treated stage I-IV (including stage IVA and IVB) squamous cell carcinoma of the upper aerodigestive tract of 1 of the following primary sites: * Oral cavity * Oropharynx * Hypopharynx * Larynx * Disease-free for at least 6 months and no more than 3 years after completion of surgery, radiotherapy, and/or chemotherapy * No synchronous tumors PATIENT CHARACTERISTICS: Age * 18 and over Performance status * Karnofsky 70-100% OR * Zubrod 0-1 Life expectancy * At least 6 months Hematopoietic * Hemoglobin ≥ 10 g/dL * WBC ≥ 3,000/mm\^3 * Platelet count ≥ 100,000/mm\^3 Hepatic * Bilirubin ≤ 1.5 mg/dL * SGOT ≤ 40 U/L * SGPT ≤ 56 U/L Renal * Creatinine ≤ 1.5 mg/dL Other * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception * No other malignancy within the past 5 years except curatively treated head and neck squamous cell carcinoma, nonmelanoma skin cancer, or carcinoma in situ of the cervix * No other serious medical or psychiatric illness that would preclude giving informed consent * No nausea ≥ grade 2 PRIOR CONCURRENT THERAPY: Biologic therapy * Not specified Chemotherapy * See Disease Characteristics * More than 6 months and less than 3 years since prior chemotherapy * No concurrent chemotherapy * No other concurrent chemopreventive agents Endocrine therapy * More than 6 months and less than 3 years since prior hormonal therapy Radiotherapy * See Disease Characteristics * More than 6 months and less than 3 years since prior radiotherapy * No concurrent radiotherapy Surgery * See Disease Characteristics * More than 6 months and less than 3 years since prior surgery * No concurrent surgery Other * More than 6 months and less than 3 years since prior investigational agents * More than 2 months since prior high-dose vitamins (i.e., 10 times the recommended daily allowance \[8,000-10,000 IU of vitamin A, 600 mg of vitamin C, or 80-100 IU of vitamin E\])