Abstract: | TS-1 is an oral anticancer drug that produces biochemical modulation. TS-1 is composed of FT (tegafur), CDHP (gimestat, which inhibits 5-FU degradation enzyme), and Oxo (otastat potassium, which reduces 5-FU gastrointestinal toxicities), in a molar ratio of 1:0.4:1. We administered TS-1 to a 68-year-old female gastric cancer patient, after distal gastrectomy (Stage IV, cur C). As a result of abdominal CT, the diameter of metastatic lymph node increased before and after surgery, and before TS-1 (45 x 35 mm), but it was reduced after 1 course of TS-1 (37 x 25 mm), 2 courses of TS-1 (35 x 20 mm), 3 courses of TS-1 (30 x 20 mm), 4 courses of TS-1 (30 x 20 mm), and 6 months after 4 courses of TS-1 (20 x 20 mm). The reduction rate is 74.6%. The value of CA125 was reduced 74.4 to 8.6 after TS-1. Anorexia and back pain, which occurred after operation, disappeared after TS-1. There was no side effect over grade 3. |