Purpose: Supratentorial pilocytic astrocytomas in adults are uncommon. A prospective clinical trial was conducted to obtain clinical and outcome data in these patients.
Methods and materials: Between 1986 and 1994, 20 eligible adults with supratentorial pilocytic astrocytomas were enrolled in a prospective intergroup trial of radiotherapy (RT) after biopsy (3 patients) or observation after gross (11 patients) or subtotal (6 patients) resection.
Results: At the time of analysis (median follow-up, 10 years), 1 patient (5%) had died and 19 patients (95%) were alive. The 5-year progression-free and overall survival rates were 95%. The cause of death in the patient who died (2.1 years after enrollment) was unknown; a radiographic examination obtained shortly before the patient's demise revealed no signs of progression. Progression in 1 patient approximately 1 month after enrollment required injection of (32)P into an enlarging cyst. The patient required RT approximately 18 months later because of further progression. This patient was alive without evidence of progression 9 years after RT. No toxic effects had been recorded at the latest follow-up examinations.
Conclusion: With follow-up comparable or superior to that in many retrospective studies, the results of this prospective trial confirm that adults with pilocytic astrocytomas have a favorable prognosis with regard to survival and neurologic function. The vast majority of patients remained stable after gross or subtotal resection and no adjuvant therapy. RT need not be offered to adults with supratentorial pilocytic astrocytoma after gross or subtotal resection; instead, close observation is recommended. Because only 3 patients received RT after biopsy, it is difficult to comment on the effect of RT on their outcome as a group.