Effects of stereotactic radiosurgery on metastatic brain tumors of various histopathologies

Although reports have been published describing clinical results in a large series of patients with metastatic brain tumors treated by stereotactic radiosurgery (SRS), clinical neuropathological correlation has rarely been available. The present paper describes three autopsy cases and one surgical case treated with linear accelerator based radiosurgery. The cases comprised a lung cancer, a rectal cancer, an osteosarcoma, and a malignant melanoma. Histological sections of each tumor were analyzed by light microscopy based on the Ohosi and Shimosato's histopathological classification of the effects of radiation therapy. In three cases (pulmonary squamous cell carcinoma, rectal adenocarcinoma and osteosarcoma), a large area of the tumors consisted of coagulation necrosis and non-viable tumor cells, while coagulation necrosis and non-viable tumor cells comprised a very small part of the malignant melanoma. Histopathological type of the metastatic brain tumor may be one of the factors influencing outcome after SRS.