EFFECT OF TIME BETWEEN X-IRRADIATION AND CHEMOTHERAPY ON THE GROWTH OF 3 SOLID MOUSE-TUMORS .1. ADRIAMYCIN

Experiments have been carried out to determine the effect of different time intervals between X-irradiation (1200 rad) and the administration of adriamycin (ADR) (6 mg/kg) on the growth delay produced in 3 mouse tumors. The tumors used were the EMT6/St/i.d. tumor in BALB/c mice and the KHT and RIF-1 sarcomas in C3H mice. All tumors were grown intramuscularly in the gastrocnemius muscle and treatment was carried out at a mean tumor weight of 450 mg. Time to reach 2X (for KHT) or 4X (for EMT6/St/i.d. and RIF-1) treatment volume was used as the endpoint of response. The drug was administered by the intraperitoneal route either 24, 6, or 2 hr before radiation, immediately before the start of radiation, or 3, 6, or 24 hr after radiation. All irradiations were carried out in unanesthetized mice. For a single administration at this dose level (close to the maximum tolerated dose), ADR alone produced only minimal growth delay in any of the tumors. Furthermore, the growth delays produced by drug/radiation combinations were not significantly different from the addition of the growth delays produced by the single modalities. © 1979.