Purpose: To determine the most effective dose of leucovorin (folinic acid [FA]) within a weekly bolus fluorouracil (FU) schedule, we conducted a randomized multicenter trial to compare therapeutic effects and toxicity of high-dose FA versus low-dose FA combined with FU at equal doses in both treatment groups.
Patients and methods: Patients with measurable inoperable or metastatic colorectal cancer were randomized to receive weekly FU 500 mg/m2 by intravenous (IV) bolus combined with high-dose FA 500 mg/m2 (group A) or low-dose FA 20 mg/m2 (group B) by 2-hour infusion.
Results: Of 291 assessable patients (group A, n = 148; group B, n = 143), we observed, in group A, complete response (CR)/partial response (PR) in 32 (21.6%), no change (NC) in 64 (43.2%), and progressive disease (PD) in 52 (35.1%); and in group B, CR/PR in 25 (17.5%), NC in 63 (44.1%), and PD in 55 (38.5%). The median response duration was 24.8 weeks in group A and 23.1 weeks in group B. Median progression-free intervals were 29.3 weeks (group A) and 30 weeks (group B). The median survival time was 55.1 weeks in group A and 54.1 weeks in group B. Overall toxicity was moderate. Mild nausea and vomiting, and stomatitis were common side effects in both groups. The incidence of World Health Organization (WHO) grade III/IV diarrhea was significantly higher in group A (40 v 23 patients). Severe side effects were observed only in a minority of patients in both arms. WHO grade IV diarrhea was observed in seven patients: four in group A and three in group B. The rate of toxicity-related adjustments of dose and schedule was comparable in both groups.
Conclusion: High-dose FA/FU is not superior to low-dose FA/FU within a weekly treatment schedule. Response rates and survival were comparable in both treatment arms. Treatment-related toxicity was higher in group A (high-dose FA). Therefore, low-dose FA combined with weekly FU may be considered the preferred treatment for metastatic colorectal cancer.