Is unchanged tumor volume after radiosurgery a measure of outcome?

We report three patients who underwent Gamma Knife radiosurgery for benign tumors (meningioma, neurinoma and hemangioblastoma), in whom an 'unchanged tumor volume' demonstrated by postirradiation follow-up neuroimaging could be regarded as a successful treatment results, as compared with preradiosurgery tumor growth. It is our view that unless significant tumor growth has been observed before radiosurgery, 'unchanged in size' after radiosurgery cannot be regarded as a successful treatment result. Because relatively few hemangioblastoma patients have been treated radiosurgically, this report emphasizes the course of one case with hemangioblastoma.