Combination therapy with methotrexate and 5-fluorouracil: a prospective randomized clinical trial of order of administration.

Because of biochemical and tissue culture evidence casting doubt on the physiologic relevance of reported synergy afforded by sequential administration of methotrexate (MTX) followed by 5-fluorouracil (5-FU), a randomized controlled clinical trial was conducted in 108 patients with advanced cancer, including 70 with squamous cell carcinoma (SCC) of the head and neck, nine with SCC of other primary sites, 24 with colorectal, and five with gastric adenocarcinomas. Patients were randomized to receive weekly therapy consisting of MTX followed one hour later by 5-FU, or 5-FU followed one hour later by MTX. There was a trend to higher tumor response rates in patients treated with MTX before 5-FU (45% v 33% overall; 65% v 39% in patients with previously untreated head and neck cancer), but these differences were not significant, either by chi-square test or by multivariate stepwise logistic regression. The trend in survival favoring the reverse sequence of 5-FU before MTX was not significant in univariate analys...