Long-term tumor control of benign intracranial tumors after Gamma Knife radiosurgery in 280 patients followed more than 5 years.

The objective of the study was to assess the long-term radiological outcome of benign intracranial tumors (BIT) after Gamma Knife radiosurgery. We report the radiological outcome of 280 patients who underwent radiosurgical irradiation for BIT in a single center. Our series included 120 meningiomas, 139 vestibular schwannomas, 12 other schwannomas and 9 pituitary adenomas. Serial imaging studies were performed after irradiation for at least 5 years for all patients. The median tumor volume was 1.9 cc, and the median margin dose was 12 Gy. After a median follow-up of 6.8 years, the tumor control rate was 92.1%: tumor decreased in 176 cases (62.9%), remained unchanged in 82 lesions (29.3%) and increased in 22 cases (7.9%). The actuarial tumor control rate was 93.2% at 5 years, 92.3% at 7.5 years and 91.0% at 10 years. No atypical or malignant transformation of irradiated tumors occured during the follow-up period. Gamma Knife radiosurgery provides a high rate of tumor control for BIT even in the medium to long-term.