Ph II Long Term/Low Dose Xeloda in Head and Neck Squamous Cell Carcinoma After Surgery, Radiation & or Chemo

DISEASE CHARACTERISTICS: Histologically confirmed squamous cell carcinoma of the head and neck, including 1 of the following primary tumor sites: Oral cavity Oropharynx Nasopharynx Hypopharynx Larynx Unknown primary Any disease stage allowed No evidence of active disease Must have undergone curative surgical resection, radiotherapy, and/or chemotherapy at least 1 month, but no more than 4 years ago PATIENT CHARACTERISTICS: Performance status Karnofsky 70-100% Life expectancy More than 3 months Hematopoietic White blood count (WBC) ≥ 3,000/mm^3 Granulocyte count ≥ 1,500/mm^3 Platelet count ≥ 100,000/mm^3 Hepatic Bilirubin ≤ 1.5 times upper limit of normal (ULN) Aspartate Aminotransferase (AST) or Alanine Aminotransferase (ALT) ≤ 2.5 times ULN Alkaline phosphatase ≤ 2.5 times ULN Hepatitis B and/or C negative Renal Creatinine clearance > 50 mL/min Cardiovascular No myocardial infarction within the past 12 months No uncontrolled congestive heart failure No unstable or uncontrolled angina Gastrointestinal No lack of physical integrity of the upper gastrointestinal tract Must be able to swallow tablet No malabsorption syndrome Other Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception HIV negative 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 for which the patient is currently in complete remission No history of uncontrolled seizures, central nervous system (CNS) disorders, or psychiatric disability that would preclude study compliance or giving informed consent No ongoing postoperative fistula No prior unanticipated severe reaction to fluoropyrimidine therapy or known sensitivity to fluorouracil No other serious uncontrolled medical or surgical condition that would preclude study participation PRIOR CONCURRENT THERAPY: Chemotherapy See Disease Characteristics Prior oral fluoropyrimidine therapy allowed provided it was given in the adjuvant setting and completed ≥ 12 months ago Radiotherapy See Disease Characteristics Surgery See Disease Characteristics More than 4 weeks since prior major surgery and recovered No prior organ allografts Other More than 4 weeks since prior participation in any investigational drug study