Abstract
We studied the combined effects of local irradiation on in vivo partially synchronized solid mouse tumors. Syngeneic fibrosarcoma cells were transplanted s.c. into the thighs of C3H/He mice. When the tumors grew to 179 cu mm in volume, 1-β-d-arabinofuranosylcytosine (ara-C) was repeatedly injected i.p. followed by a single injection of vinblastine sulfate at 5 hr after the end of the ara-C treatment. The mitotic indexes increased from 4% in control to 22 to 23% at 5 hr after the ara-C treatment, and the level continued for another 5 hr. Further treatment with vinblastine sulfate after the ara-C injections resulted in more effective accumulation of mitotic cells, i.e., 30% at the sixth hr. The tumor was locally irradiated with a single dose of 3000 rads of γ-rays at the maximum level of mitotic index. The results indicated a synergistic inhibition of tumor growth and an 84% prolongation of the 50% survival day beyond that of the nontreated control mice.
This work was supported in part by a Grant-in-Aid for Cancer Research from the Ministry of Education, Science, and Culture.