Analysis of the proliferative potential of residual tumor after radiosurgery for intraparenchymal brain metastases.

A retrospective immunohistochemical study of radiosurgically treated brain metastases was performed to determine whether residual tumor has reduced proliferative potential. The monoclonal antibodies MIB-10 and PC-10 were used as markers for proliferation. The experimental group consisted of pathological specimens obtained from five patients in whom brain metastasis previously had been treated with radiosurgery. Pathological specimens obtained from 10 patients with brain metastases, matched in histology to diseases in the experimental group but untreated by radiosurgery, served as controls. A significant decrease in proliferative indices was observed in metastatic brain cancers after radiosurgery (p < 0.001). These results indicate that the persistent tumor that is present at the site of a metastasis previously treated with radiosurgery is less viable and may not in itself be a significant finding.