[A case of CA19-9 producing gastric cancer treated by low-dose administration of TS-1 for adjuvant chemotherapy].

A 72-year-old woman underwent total gastrectomy for CA19-9 producing gastric cancer. TS-1 was administered for recurrent gastric cancer because the duodenal stump was histologically positive and the serum CA19-9 level elevated after temporary regression. The dose was reduced from 80 mg/body/day to 50 mg/body/day because of grade 3 neutropenia. One course consisted of consecutive administration for 28 days followed by 14 days' rest. Upon the completion of the second course, the serum CA19-9 level became within normal limits, and no recurrence nor remarkable adverse reaction has been recognized for 6 courses. Adjuvant use of TS-1 for gastric cancer is ongoing as clinical trials, however, the incidence of adverse reaction does not seem to be negligible with administration of the recommended dose. Low-dose administration of TS-1 is thought to be one effective method of postoperative adjuvant chemotherapy for gastric cancer.