Mitomycin C

Abstract

Thirty patients received mitomycin C by constant infusion for 5 consecutive days (16 patients ) or for extended period by an ambulatory infusion pump (Cor-Med model) for 9 to 30 days (14 patients). The short-term 5-day infusions were delivered at dose rates of 2, 3, 4, 5 and 6 mg/m2/d with a cumulative dose of 15-50 mg. The protracted infusions were delivered at dose rates of 0.75-3 mg/m2/d with a cumulative dose of 21.6-65.2 mg. Marrow suppression was dose-limiting and occurred in 5/6 evaluable patients receiving more than 30 mg in the short-term infusion schedule and 8/10 evaluable patients receiving more than 20 mg in the protracted infusion schedule. The characteristics of the marrow suppression are that: a) thrombocytopenia precedes or is observed without concomitant leukopenia and b) the nadir day is delayed (WBC day 42, platelet day 36). Mitomycin C delivered by constant infusion leads to dose-limiting marrow toxicity at 20 to 30 mg cumulative dose depending upon the dose rate and duration of treatment. For short-term 5-day therapy, 3 mg/m2/d and for protracted therapy (up to 30 d) 0.75 mg/m2/d are the recommended dose rates for the constant infusion schedule.