Two Cases of Patients with Advanced Gastric Cancer Completely Responding to the TS-1 Treatment

Patient 1: a 58-year-old man visited to the hospital for treatment of double gastric cancers on the body and antrum of the stomach. He received daily oral administration of 100 mg TS-1, a novel oral anticancer agent, the treatment course of which consisted of a four-week administration followed by two drug-free weeks before the operation. A pathological examination revealed no cancer cells in the resected specimen, and that was considered as complete response (CR). Patient 2: An 87-year-old man, who had diabetes mellitus, asthma, hypertension, an old myocardial infarction, and early laryngeal cancer followed by radio therapy, visited the hospital because of progressive appetite loss. A gastrointestinal endoscopic examination revealed an ulcerative lesion at the upper side of the stomach, and the pathological examination of the biopsy specimen showed papillary adenocarcinoma. He chose the TS-1 chemotherapy, rather than an operation in consideration of the risk of his age and multiple complications, and received a daily oral administration of 100 mg TS-1. This treatment was, however, stopped because of leukocytopenia and severe fatigue just before completion of two courses. An endoscopic examination showed that the tumor size was dramatically reduced at the 19th day after the start of this treatment, and the primary tumor was reduced to an ulcer scar with pathological confirmation of a complete disappearance of the cancer tissue at the 140th day. TS-1 treatment for an advanced gastric cancer may be recommended as one of the therapeutic strategies especially for a patient with a high surgical risk.