S-1 or Tegafur-Uracil in Treating Patients With Previously Treated Stage III or Stage IV Head and Neck Cancer

DISEASE CHARACTERISTICS:

* Histologically or cytologically confirmed squamous cell carcinoma of the head and neck (SCCHN)

  * Stage III or IV disease
  * Primary tumor in the mesopharynx, hypopharynx, larynx (except T3 N0 tumors of the glottis), oral cavity, or maxillary sinus
* Completed definitive treatment for SCCHN within the past 3 months, that included any of the following:

  * Surgery
  * Chemotherapy
  * Biologic therapy
  * Radiotherapy (e.g., radiotherapy in combination with chemotherapy or pre- or postoperative radiotherapy)
  * Any other treatment
* No clinical evidence of locoregional tumors or distant metastasis within 3 months after the completion of definitive treatment

PATIENT CHARACTERISTICS:

* ECOG performance status 0-1
* WBC ≥ 3,500/mm\^3 AND ≤ 12,000/mm\^3
* Neutrophil count ≥ 2,000/mm\^3
* Platelet count ≥ 100,000/mm\^3
* Hemoglobin ≥ 9 g/dL
* AST and ALT \< 100 IU/L
* Bilirubin \< 1.5 mg/dL
* Creatinine \< 1.2 mg/dL
* No uncontrolled cardiovascular disease
* No interstitial pneumonia or pulmonary fibrosis
* Must have sufficient oral intake

PRIOR CONCURRENT THERAPY:

* See Disease Characteristics
* No concurrent biologic therapy, radiotherapy, other chemotherapy, or any other therapy