Response of extra-axial tumors to stereotactically implanted high-activity 125I seeds.

125I seeds can deliver a very high dose of radiation (100-500 Gy) to a well-circumscribed area over their average life of 87 days, which enable them to destroy slow-growing extra-axial tumors after permanent implantation. Stereotactic implantation of 125I seeds was performed in 26 patients with extra-axial tumors, with a median follow-up of 32 months. No acute morbidity or mortality resulted from the procedure. Cranial nerve involvement in 5 patients was the only delayed complication. One patient developed radionecrosis outside the range of 125I dose distribution, which was felt to be due to the hyperfractionated external radiation the patient had received prior to 125I seed placement. All 26 patients showed tumor regression. The results indicate that this form of treatment is relatively safe and effective in the management of extra-axial tumors.