Stereotactic radiosurgery for well-circumscribed fibrillary grade II astrocytomas: an initial experience

OBJECTIVE: To examine the role of stereotactic radiosurgery in the management of patients with progressive, well-circumscribed grade II fibrillary astrocytomas. METHODS: During a 13-year interval, 12 patients (median age: 25 years) required multimodality management for recurrent or unresectable World Health Organization (WHO) grade II fibrillary astrocytomas. Tumors involved the brainstem (n = 4), thalamus (n = 1), cerebellum (n = 1), frontal lobe (n = 4), temporal lobe (n = 1), and parietal lobe (n = 1). Diagnosis was confirmed by stereotactic biopsy (n = 5), partial resection (n = 5), and near total resection (n = 2). Multimodality management of patients prior to radiosurgery included fractionated radiation therapy (n = 4), stereotactic cyst drainage (n = 1), and ventriculoperitoneal shunt placement (n = 2). Tumor volumes varied from 1.2 to 45.1 cm(3). The median radiosurgical dose to the tumor margin was 16 Gy. RESULTS: After radiosurgery, serial imaging showed complete tumor resolution in 1 patient, reduced tumor volume in 4, stable tumor volume in 3, and delayed tumor progression in 4 (3 patients with increase in cyst size only). Therapy after radiosurgery included additional cytoreductive surgery (n = 1) for recurrence of a higher grade tumor, stereotactic cyst aspiration (n = 1), and stereotactic intracavitary irradiation (n = 1). All patients were alive at a median follow-up of 52 months after radiosurgery and 103 months after diagnosis. In 8 patients, follow-up lasted more than 60 months. CONCLUSION: Stereotactic radiosurgery is a potential alternative or adjunctive strategy in the management of selected patients with WHO grade II fibrillary astrocytomas.