[Treatment of rectocolic and gastric adenocarcinomas with 5-fluorouracil associated with high doses of folinic acid. Results of an experimental study].

We report the results of a therapeutic trial in patients with rectocolic and gastric metastatic adenocarcinomas. This trial is based on experimental evidence that an excess of reduced intracellular folic acid increases the cytotoxicity of fluoropyrimidines. The treatment consists of 5-fluorouracile (5-FU) (370 to 400 mg/m2/24 h) and folinic acid in high doses (200 mg/m2: 24 h) given simultaneously for 5 consecutive days; the interval between courses is 21 days. Thirty patients with measurable rectocolic adenocarcinomas were evaluated. They were divided into two groups: 16 patients had had no previous chemotherapy and 14 had not responded to chemotherapy with 5-FU alone or associated with other cytostatic drugs. Response rates were 56% in the first group and 21% in the second. Five patients with measurable gastric adenocarcinomas were also evaluated; none had received previous chemotherapy. A partial response was recorded in three of these patients. Toxicity of the therapeutic regimen was acceptable. Stomatitis was the most common toxic side-effect. In patients with severe adverse side-effects recurrence was efficiently prevented by decreasing the daily dose of 5-FU to 30 mg/m2 during subsequent courses. We conclude that in the tumors studied folinic acid in high doses can improve the antitumoral effect of 5-FU and induce a response to this agent in some rectocolic tumors which were previously resistant.