Feasibility study of adjuvant chemotherapy with S-1 (TS-1; tegafur, gimeracil, oteracil potassium) for gastric cancer
We conducted a feasibility study using S-1, a novel oral derivative of 5-fluorouracil, as postoperative adjuvant chemotherapy for curatively resected gastric cancer patients.
Adjuvant chemotherapy consisted of eight courses (4-week administration and 2-week withdrawal) of S-1, at 80–120 mg/body per day. Forty-one patients from 11 institutions were enrolled in this pilot study, from November 1999 to October 2000.
Thirty-five patients were eligible. In 7 patients, S-1 administration was discontinued due to recurrence. Among the 28 patients without recurrence, the planned eight courses of S-1 were administered to 17 patients (60.7%). In 4 patients, S-1 administration was discontinued due to subjective symptoms, such as anorexia, in the first course. Adverse reactions such as neutropenia, leukopenia, elevated total bilirubin, anorexia, general fatigue, diarrhea, nausea, and stomatitis were seen in more than half of the patients. Although grade 3 neutropenia (29.3%), leukopenia (9.8%), and diarrhea (9.8%) were observed, no grade 4 adverse effects appeared. Compared with the treatment of unresectable or recurrent gastric cancer with S-1, the incidence of adverse reactions in the adjuvant setting was slightly higher, probably due to the influence of gastrectomy.
Except for the early development of anorexia, most likely due to adverse effects of surgery, postoperative administration of S-1 for 1 year seems feasible as adjuvant chemotherapy for gastric cancer.