Continuous 5-fluorouracil infusion and pulse methotrexate/leucovorin for colorectal adenocarcinoma. A report of excessive toxicity.

Thirteen patients with metastatic colorectal adenocarcinoma underwent treatment with continuous ambulatory 5-fluorouracil (5-FU) infusion 300 mg/m2/day and intermittent bolus methotrexate (MTX) (200 mg/m2) with calcium leucovorin (LCV) 10 mg/m2 orally every 6 h X four to eight doses given 24 h after MTX. Although MTX administration was planned every 14 days, the average time between treatments exceeded 19 days (range 14-42) because of excessive toxicity. All patients experienced toxicity at some time in their treatment course, requiring interruption of 5-FU infusion in 12 of 13 patients. Significant toxicities included stomatitis (13 of 13 patients), hand-foot syndrome (8 of 13 patients), and diarrhea (3 of 13 patients). Toxicity did not appear to be minimized by attenuation of MTX and/or 5-FU dosage or by increasing the dose and/or duration of LCV. At this dosage schedule the addition of MTX/LCV to 5-FU infusion results in excessive and unacceptable toxicity and does not appear to improve treatment results.