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])