Feasibility study of adjuvant chemotherapy with S-1 (TS-1; tegafur, gimeracil and oteracil potassium) for colorectal cancer.

BACKGROUND/AIMS: The aim of this study is to evaluate feasibility and safety of 3-week method (3-week administration and 1-week withdrawal) for colorectal cancer as adjuvant chemotherapy with an oral anticancer drug, S-1.

METHODOLOGY

Forty-two patients with stage II or III colorectal cancer who underwent curative resection in our hospital during a one year period in 2005 were enrolled in the preliminary pilot study. Between 2006 and 2007, 104 patients with stage II or III colorectal cancer who underwent curative resection in our hospital were chosen and were randomly divided into two groups, 3-week method or 4-week method (4-week administration and 2-week withdrawal) for a prospective randomized trial.

RESULTS

The one-year completion rate in the 3-week method group was 98% (50/51) which was significantly better than that in the 4-week method group, 68% (36/53) (p=0.035). There were no grade 3 or 4 adverse reactions in both laboratory and clinical findings in the pilot study and in the prospective randomized trial.

CONCLUSIONS

Three-week method of S-1 administration had good feasibility, easily manageable toxicity, high accumulated dose in one year and good compliance. The 3-week method with S-1 may be a standard adjuvant chemotherapy schedule for colorectal cancer.