Weekly 24-hour infusion with high-dose 5-Fluorouracil and 6s-leucovorin as a 2nd-line therapy in advanced colorectal-cancer resistant to a 5-fluorouracil/6s-leucovorin bolus combination.

Recently, experimental data suggested the possibility that resistance to 5FU may be overcome by administering the drug in a different schedule. To test this hypothesis we treated seventeen patients, who failed to respond to a common 5FU/leucovorin bolus regimen, with an intravenous infusion of 6S-leucovorin, at a dose of 250 mg/m(2), concurrently with 5FU at 2,600 mg/m(2) over a 24-hour period. Treatment was repeated every week.