Pilot study of simplified low-dose S-1 plus CPT-11 as first-line chemotherapy for patients with advanced colorectal cancer.

BACKGROUND

S-1 is a novel oral anticancer drug, composed of tegafur (FT), gimestat (CDHP) and otastat potassium (Oxo) in a molar ratio of 1:0.4:1. S-1 plus irinotecan (CPT-11) administered for advanced colorectal cancer could be expected to show as equally good results as the infusional 5-fluorouracil/leucovorin (5-FU/LV) with CPT-11 (FOLFIRI) regimen. When toxicity is too severe preventing patients from receiving an intensive chemotherapeutic regimen, survival benefit might be forfeited. A pilot study of low-dose S-1 plus CPT-11 therapy with constant doses without consideration of body surface area (BSA) was therefore performed.

PATIENTS AND METHODS

Twenty-two patients were enrolled in this study. S-1 was given orally at 40 mg b.i.d. for 21 consecutive days followed by a 14-day rest period. CPT-11 was administered as a 90-minute intravenous infusion at a dose of 80 mg on days 1 and 15. Courses of treatment were repeated every 35 days.

RESULTS

The median age was 62.5 years (26-74). The median cycles were 8.5 (3-20). The overall response rate was 45.5% (complete response (CR), 1; partial response (PR), 9). Median progression-free survival (PFS) and median overall survival time (MST) were 9.0 and 20.2 months respectively. No grade 3 or 4 toxicities were observed. Eight patients (36.4%) did not have any sign or symptom of toxicity throughout all the treatment courses. The response, survival and toxicity were not significantly different according to BSA.

CONCLUSION

These results suggest that simplified low-dose S-1 plus CPT-11 treatment might be of considerable advantage as first-line chemotherapy for patients with advanced colorectal cancer who would like to avoid toxicity.