Clinicopathological study of brain tumor radiotherapy.

A clinicopathological study was made on 45 autopsy cases of brain tumors treated with radiotherapy. Morphological changes after radiotherapy were classified into six categories : 1) tumor disappearance, 2) small residual tumor, 3) extensive tumor necrosis, 4) proliferative tumor growth, 5) mixed glioblastoma and fibrosarcoma, and 6) no remarkable change. When the tumors are primarily radiosensitive, tumor disappearance or small residual tumors might occur. Germinomas, some of lymphomas and medulloblastomas were representative of primary radiosensitivity. When the tumors are secondarily radiosensitive, or tumor cell necrosis is brought about by blood vessel degeneration caused by radiation, there might be extensive tumor necrosis. About one a half of the astrocytic tumors and glioblastomas were thought to have a combination of primary and secondary radiosensitivity. One case of oligodendroglioma, two cases of ependymoblastoma, two cases of malignant lymphoma and two cases of metastatic tumor also showed extensive tumor necrosis. The other half of the astrocytic tumors and glioblastomas showed proliferative tumor growth. They seemed to be less radiosensitive. Two cases of glioblastoma at the time of the operation changed into mixed glioblastoma and fibrosarcoma in the autopsy. No remarkable changes were ob served in cases of teratoma and pineocytoma which were mature benign tumors with little blood vessel supply. No definite correlations were observed between the pathological changes and therapies such as the degree of resection, doses of irradiation and chemotherapy in astrocytic tumors and glioblastomas. There were, however, some tendencies for small residual tumors and extensive tumor necrosis to be brought about by extensive tumor resection, full courses of radiotherapy and intensive chemotherapy.