Management of adjuvant S-1 therapy after curative resection of gastric cancer: Dose reduction and treatment schedule modification

Abstract

Background: The aim of this study was to determine the optimal management of adjuvant S-1 therapy for stage II or III gastric cancer, encompassing the details of dose reduction and treatment schedule modification. Methods: We retrospectively examined 97 patients with stage II or III gastric cancer who received S-1 chemotherapy following gastrectomy between January 2003 and December 2007. S-1 (80 mg/m2 per day) was orally administered twice daily for 4 weeks, followed by a 2-week rest. As a rule, treatment was continued for 1 year after gastrectomy. Dose reduction or treatment schedule modification was performed according to toxicity profiles. Results: Among the 97 patients, 57 (59%) underwent dose reduction at least once and 39 (40%) received treatment schedule modification. Of the 57 patients who required dose reduction, 45 (79%) underwent reduction within 3 months of the beginning of treatment. The most common reasons for dose reduction were anorexia (47%), followed by diarrhea (32%), leukopenia (24%), and rash (16%), with the reasons overlapping. Although the difference in the requirement for dose reduction was not significant, patients with a low creatinine clearance level or those who underwent total gastrectomy had a greater tendency to require dose reduction. The duration of the S-1 treatment period was at least 3 months in 88% of the patients, at least 6 months in 82%, and the planned 1-year period in 73% of the patients. Conclusions: In most patients, the planned 1-year adjuvant S-1 therapy for stage II or III gastric cancer could be completed by modifying the dose reduction and treatment schedule. © 2011 The International Gastric Cancer Association and The Japanese Gastric Cancer Association.