Increasing doses of 5-fluorouracil and high-dose folinic acid in the treatment of metastatic colorectal cancer

Aims and background Combined 5-fluorouracil (5FU) and folinic acid (FA) is the first-line treatment of metastatic colorectal cancer. The aims of this study were to individualize the dose of 5FU in a weekly schedule in which the maximum tolerated dose of 5FU is administered to each patient, and to evaluate the impact of increasing 5FU doses on response and survival. Methods Thirty-two patients (30 evaluable for response) with metastatic colorectal cancer were treated with weekly intravenous doses of FA 150 mg/m2 and a fast infusion of 5FU, at an initial dose of 600 mg/m2 which was increased by 60 mg/m2 every week until the appearance of a side effect, in order to determine the maximum tolerated dose for the patient. Results We obtained 11 objective responses (36.7%, median survival 22 months) and 15 disease stabilizations (50%, median survival 15 months); there were four cases of progressive disease (13.3%, median survival 4 months). The overall survival was 15 months. Twenty-eight patients (87.5%) tolerated 5FU doses of 720 mg/m2 or more. Conclusions Weekly 5FU with high-dose FA modulation can be individualized by dose escalation. A 5FU dose of 720 mg/m2 per week seems to be critical, as higher doses are no more effective and lead to severe side effects. This schedule gives good results in terms of response, even though the complete response rate remains low.