Craniopharyngiomas: A six year experience with Gamma Knife radiosurgery.

The focused radiation produced by radiosurgery offers the theoretical advantage of a reduced radiation dose to surrounding structures during the treatment of residual craniopharyngiomas when compared with fractionated radiotherapy. A retrospective analysis of 23 patients treated since 1992 was undertaken. Intracystic bleomycin treatment in 10 patients with cystic tumors proved to be effective in preparing the tumors for radiosurgery. The mean prescription dose in this series was 10.8 ¿ 8.7 Gy delivered to a mean prescription 47% isodose. There was a volume reduction of the residual tumor in 74%. In this series, initial tumor volume and target volume were significant prognostic factors. Smaller tumors and targets were more likely to shrink. Five patients with large multicystic residual or recurrent tumors after multiple surgical attempts showed further progression. The maximum radiation dose, prescription dose and choice of prescription isodose were not significant prognostic factors within this series. Radiosurgery resulted in no mortality and no significant morbidity could be attributed to it. Clinically, the best results with radiosurgery were obtained with monocystic tumors amenable to stereotactic drainage and intracystic bleomycin treatment.