[Continuous administration and safety of S-1 in adjuvant chemotherapy for gastric cancer].

Patients taking more than 8 courses of S-1 were classified in the continuous group (n=30) and those in whom S-1 was discontinued or reduced due to adverse reactions in the discontinuation/reduction group (n=29). Factors affecting the continuous administration of S-1 as the adjuvant chemotherapy were examined in the two groups. 10 cases in the continuous group and 8 cases in the discontinuation/reduction group began with a stage 1 reduction of the S-1 regimen. Significant factors which affected the reduction or discontinuation of S-1 due to adverse reactions were 1) serum albumin value (Alb) (odds ratio 9.227; 95% confidence interval 1.056-80.603, p=0.0196) and 2) creatinine clearance value (Ccr) (odds ratio 5.850; 95% confidence interval 1. 222-27.995, p=0.0221). Among the reasons for reduction or discontinuation, non-hematotoxicities including malaise, nausea and diarrhea accounted for 24/59 cases (40.7%) and hematotoxicities such as leukopenia for 5/59 cases (8.5%). The present study revealed that most of the reduction or discontinuation of S-1 was due to non-hematotoxicity such as malaise and suggested that these risks increased when Alb decreased to less than 3.5 g/dL and Ccr to less than 80 mL/min. Prognosis is reportedly satisfactory when administration of S-1 is continued for one year even if withdrawal or reduction is necessary during the period. Serious adverse reactions will have ill effects on future compliance with to administration in patients who have experienced them. The above results indicate that the occurrence of non-hematotoxicity should be observed carefully in patients with Alb less than 3.5 g/dL and Ccr less than 80 mL/min at the beginning of S-1 administration, and these patients should receive appropriate guidance. Modification or reduction of S-1 regimen at the beginning may be one way to alleviate hematotoxicity.