Randomized Controlled Study of Postoperative Adjuvant Therapy for Gastric Cancer Using TS-1 or TS-1+PSK

Inclusion Criteria: * Patients with microscopic stage II or IIIA resectable gastric cancer * Patients who have not received preoperative cancer therapy (radiotherapy, chemotherapy or immunotherapy) * Patients with serum immunosuppressive acidic protein (IAP) measured within 2 weeks before surgery * Patients with no metachronous or synchronous multiple cancer * Patients without severe impairment of renal, hepatic and bone marrow functions * Patients who are judged to be capable of tolerating surgery * Patients with preoperative performance status 0 to 2 * Patients with no serious concurrent complications (such as bone marrow suppression, diarrhea and infection) * Patients who are judged to be capable of tolerating this treatment, and who have given written informed consent to participate in this study Exclusion Criteria: * Patients with fresh hemorrhage from the gastrointestinal tract * Patients with retention of body fluid necessitating treatment * Patients with infection, intestinal palsy or intestinal occlusion * Patients who are pregnant or hope to become pregnant during the study period * Patients with diabetes treated by continuous use of insulin or showing poor glycemic control * Patients with a history of ischemic heart disease * Patients with concurrent psychiatric disease or psychotic symptoms, and judged to have difficulties participating in the study * Patients receiving continuous administration of steroids * Patients who have experienced serious drug allergy in the past * Others, patients judged by the investigator or subinvestigator to be inappropriate as subject