The pilocytic astrocytoma is assigned as grade 1 in WHO classification 2007 and the surgical resection is curative. However, complete surgical resection is not always eligible for diverse causes.

     Authors reviewed the outcome of Gamma knife radiosurgery in order to evaluate the role of Gamma knife radiosurgery (GKS) in pilocytic astrocytomas.

     Between 1997 and 2008, 13 pilocytic astrocytomas were irradiated through GKS. Only seven patients (3male and 4 female, mean age 20.1 years), who were followed-up more than 6 months, were included in this study. Five tumors were the post-operative residual lesions and there were two recurrent lesions. Four lesions were located in the posterior fossa, including two brain stem lesions.

     The median volume of lesion was 3.3cm3 (range; 0.14 ~ 8.3) and mean irradiation dose was 16.1 Gy (range; 11~20). The mean follow-up period was 30months (range; 6 ~95).

     There was no radiation-related adverse reaction. All tumors were controlled except one. The progressive case suffered neurofibromatosis type 1. There was no other noticeable clinical and radiosurgical factor regarding to the recurrence.

     This is a retrospective study.

     The GKS is effective as an adjuvant modality in the management of pilocytic astrocytomas.