SOLID TUMOR-MODELS FOR THE ASSESSMENT OF DIFFERENT TREATMENT MODALITIES .18. CHANGES IN GROWTH-RATE OF AN EXPERIMENTAL SOLID TUMOR FOLLOWING INCREASING DOSES OF CYCLOPHOSPHAMIDE

  • 1 January 1980
    • journal article
    • research article
    • Vol. 40  (7) , 2179-2183
Abstract
Well-defined times for minimum and maximum growth rates of rat hepatoma 3924A cells were found when cyclophosphamide doses were increased from 50 to 250 mg/kg. Minimum growth rates occurred 8-10 days after treatment and maximum growth rates occurred 13 to 16 days after treatment in 5 groups of 10 animals each that received 50, 100, 150, 200 and 250 mg of cyclophosphamide per kg. Tumor growth delay increased from 6 to 18 days when the dose was increased from 50 to 250 mg/kg. The accelerated growth rate of treated tumors on day 14 after cyclophosphamide (150 mg/kg) was more than twice that of controls on the same day, 0.349 .+-. 0.030 (SE) (day-1) and 0.156 .+-. 0.011 (day-1), respectively. The accelerated growth rate of treated tumors on day 14 was greater than that of controls at initiation of treatment, 0.298 .+-. 0.026 (day-1) on day 2. Increased DNA synthetic rate precedes increased tumor cell proliferation, which, in turn, increases tumor volume. Biochemical studies demonstrating increased cellular proliferation confirm accelerated tumor growth following treatment.