Treatment of autochthonous rat brain tumors with chemotherapy and radiotherapy

: The authors tried to establish a model of primary, autochthonous avian sarcoma virus-induced rat glioma for experimental chemotherapy and radiotherapy. It was found that the intracerebral inoculation of 2 X 10(6) FFU/5 microliter of an infectious cells-free homogeneous sub-group D Schmidt-Ruppin avian sarcoma virus into 3-day-old inbred Fischer rats induced brain tumors in all rats. The mean survival time of the inoculated rats was 58.7 +/- 12 days. With regard to the classification of the induced brain tumors in Fischer rats, astrocytoma accounted for 70%. This ASV-induced tumor in rats fulfills the following criteria for a desirable animal model. Spontaneously arising. Glial origin. Intraparenchymal growth. Uniformly fatal within a reasonable time period. In the present study, the therapeutic effects of anticancer drugs, such as ACNU and vincristine were evaluated and additionally, the effect of ACNU used in conjunction with radiation was also evaluated in this model. The mean survival time of rats was prolonged significantly with ACNU (20 mg/kg) or radiation therapy (1,000 rads), respectively, and in cases where ACNU was used together with radiation, the mean survival time was prolonged further still, but not very significantly, in comparison with radiation therapy alone. In conclusion, the ASV-induced rat glioma model was considered to be closely akin to a spontaneous brain tumor in terms of morphology, blood supply and kinetics of the primary tumor. Moreover, the therapeutic sensitivity of this model to anticancer drugs was fairly similar to that of human anaplastic astrocytoma. Considering these observations, this model seems to be an excellent experimental brain tumor model which is useful for evaluating the effect of new therapies against malignant brain tumors.