The investigators confirm the feasibility of 1-year administration of oral fluoropyrimidine S-1 as an adjuvant chemotherapy for the patient who received complete resection of non-small cell lung cancer. The investigators presume they can achieve high completion rate with low toxicity.

Chemotherapy comprised eight courses (4-week administration, 2-week withdrawal) of S-1 (FT, gineracil, oteracil potassium; Taiho Pharmaceutical, Tokyo, Japan) at 80-120 mg/body/day according to body surface area (BSA): BSA <1.25 m2, 80 mg/day; BSA >1.25 m2 but <1.5 m2, 100 mg/day; and BSA >1.5 m2, 120 mg/day. S-1 was administered orally, twice daily after meals, starting within 4 weeks after surgery.

Inclusion Criteria:

1. NSCLC with histological proof.
2. Pathological stage IB, II, or IIIA NSCLC (fifth edition of UICC/AJCC 1997) after complete resection.
3. No prior treatment except for surgery.
4. Sufficient oral intake.
5. Performance status (PS) 0 or 1.
6. Patients also had to have adequate organ function (3500 <leukocytes < 12,000/mm3; thrombocytes, >100,000/mm3; total bilirubin,<1.5 mg/dl; AST and ALT, less than twice the normal limits at each institution; BUN, <25 mg/dl; creatinine, less than the normal limits at each institution; and creatinine clearance (Ccr))

Exclusion Criteria:

1. History of drug hypersensitivity.
2. Contraindication of oral S-1 administration (refer appended paper).
3. Serious surgical or non-surgical complications
4. Active secondary cancer.
5. Watery diarrhea.
6. Pregnant or lactating women.
7. Male who has intention to make pregnant
8. Patient to whom primary doctor judged inadequate to register.