Abstract
In the present studies, the interaction of adriamycin (A) and x-irradiation (X) in T1699 mouse mammary tumors was evaluated. Mitotic indices and thymidine labeling indices were determined at various intervals after A or X alone, and after A + X given in combination. The results with A (1.0 mg/kg) and X (200 R) alone suggests that those quantities of each agent induce a G
2 progression delay of 9–12 brs. The kinetic results after A + X in combination indicated increased S phase transit. time and G
2 progression delay. Recovery kinetics after A + X were used to predict “optimmn” sequence intervals for subsequent A + X fractions. Sequential A + X treatment schedules, up to 4 fractions, were designed and evaluated by regrowth delay measurements. The results indicated that the interaction was additive when A and X were given together in combination. Fractionation of A + X to minimize proliferstive recovery between fractions resulted in an enhanced antitumor effect.
