RATIONALE: Drugs used in chemotherapy, such as S-1 and tegafur-uracil, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Giving S-1 or tegafur-uracil after surgery, chemotherapy, biological therapy, and/or radiation therapy may kill any remaining tumor cells. It is not yet known whether S-1 is more effective than tegafur-uracil in treating head and neck cancer.

PURPOSE: This randomized phase III trial is studying S-1 to see how well it works compared with tegafur-uracil in treating patients with previously treated stage III or stage IV head and neck cancer.

OBJECTIVES:

• Compare the disease-free survival rate in patients with definitively treated stage III or IV squamous cell carcinoma of the head and neck treated with adjuvant chemotherapy comprising S-1 vs tegafur-uracil (UFT).

OUTLINE: This is a randomized, controlled, multicenter study. Patients are stratified according to primary site, disease stage, type of prior definitive treatment, and participating center. Patients are randomized to 1 of 2 treatment arms.

• Arm I: Patients receive oral S-1 once daily on days 1-14. Courses repeat every 21 days for 1 year in the absence of disease progression or unacceptable toxicity.
• Arm II:Patients receive oral tegafur-uracil (UFT) once daily on days 1-21. Courses repeat every 21 days for 1 year in the absence of disease progression or unacceptable toxicity.

PROJECTED ACCRUAL: A total of 500 patients will be accrued for this study.

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