The 6-day subrenal
capsule assay for determining chemotherapeutic sensitivities of
brain tumors was studied. Rat
glioma 9L and
ACNU resistant 9L-2 were transplanted under the renal
capsule of normal immunocompetent WKA rats for laboratory investigation. Evaluation of implanted
tumor growth till 12 days was performed. The effects of chemotherapeutic agents administered intravenously were evaluated by measuring the growth rate of implanted
tumor specimens. The results obtained from SRC were compared with the results from colony forming assay. Both were correlated to each other. On the other hand, histological investigation revealed that implanted human
tumor cells had been diminished and implanted
tumor was replaced by immunoreactive cells from the host in many cases. These results threw doubt on a reliability of SRC. To avoid this immunoreaction,
cyclophosphamide was injected as
immunosuppressive agent subcutaneously 24 hours before implantation. In such cases, the growth rates of implanted
tumors were increased and histologically the implanted
tumor cells existed for 6 days after implantation. Twenty-three malignant
brain tumors (malignant
astrocytomas 16, metastatic
tumors 5,
malignant lymphoma 2) were obtained as surgical specimens. Evaluable assay rate of our study were 89%. 15 patients with malignant
astrocytomas were studied about correlation between the sensitivities of
ACNU and post-operative clinical courses. Overall clinical correlation of 15 cases of malignant
astrocytomas was 47%. These results from subrenal
capsule assay are not seemed to be beneficial for clinical use. Immunoreactive response when using immunocompetent rats must be solved in future.