Efficacy of single-bolus vs. frequent low-dose treatment with nitrosourea in experimental gliomas

Background: Malignant glioma remains a fatal disease. Continuous or frequent low-dose (FLD) chemotherapy with nitrosoureas reportedly causes fewer side-effects than single-bolus therapy without decreasing the antitumour effects. Materials and Methods: To study the effect of FLD treatment with nimustine (ACNU) in rats with glioma, we intracerebrally inoculated with C6 glioma cells. We began the ACNU treatment 5 or 8 days later (total dose, 25 or 40 mg/kg) i.p. as either one bolus or smaller doses spread over 5 days week. Results: At a total dose of 25 mg/kg beginning at day 8, survival duration did not differ between untreated controls and the FLD group, while the bolus significantly prolonged survival; the FLD group showed some improvement beyond control survival at 40 mg/kg (each p <0.001). Beginning treatment after 5 rather than 8 days prolonged survival somewhat further. Conclusion: FLD treatment with ACNU is less effective against experimental glioma in rats than bolus treatment.