Radiation therapy of rat brain tumor using misonidazole as hypoxic cell sensitizer.

Rat brain tumor was used as a model to evaluate radiation therapy with and without misonidazole. BD-IX rats were implanted intracerebrally with an ethylnitrosourea-induced glioma. Three series of experiments were performed, with radiation given 14 days after inoculation of the glioma clone. In each series, the following radiation doses were given: 500 rads once, 1,000 rads once; and 1,000 rads twice, every time with or without two different doses of misonidazole. Radiation therapy significantly prolonged survival when compared to the longevity of the control group. The dose of 1,000 rads given twice was highly effective and the life-span of tumor-bearing rats increased from 72% to 121%. Misonidazole plus irradiation negated the prolongation of survival, achieved with radiation therapy alone.