Does pilocytic astrocytoma (PA) in adults have a different prognosis than PA in children?

Abstract

Background: Pilocytic astrocytoma (PA) accounts for up to 25% of all brain tumors in children. A 75% progression-free survival rate at 5 years and overall survival rates of 95.8% at 10 years have been reported after a complete resection. However, the incidence in adults is low and the outcome less well characterized. We conducted a retrospective analysis of adult PAs identified in order to review the clinical characteristics and outcome of this neoplasm in this age group. Methods: A descriptive, cross-sectional study was undertaken in patients over 16 y.o., diagnosed with PA between January 1990 and December 2010 at our center. Clinical characteristics, date and extent of surgery, tumor location, postoperative treatment, complications and recurrences were collected from hospital records. Results: From May, 1990 to December, 2010, 18 eligible adult patients (pts) with the diagnosis of PA were identified. Median age was 25,5 (16-52) years, 72,2% female and 83,3% had an ECOG performance status ≤ 2. The most frequent tumor sites were the cerebellum (44,4%), followed by the cerebral hemispheres (38%). All patients underwent surgery as primary treatment, 72% had a complete macroscopic resection (CMR) and 28% had a partial resection (PR). Two patients received postoperative radiotherapy: one following a PR and the other after tumor relapse following a CMR. Two patients relapsed five months and 44 months after initial complete gross resection. Salvage surgery achieved CMR in both. With a median follow-up of 89 months, all patients are alive, except for one who died in the postoperative period due to fungal meningitis. Of note, none of 5 pts undergoing a partial resection progressed and 3 are alive for more than 10 years. Conclusions: As it occurs in the pediatric population, PA in adults seems to carry a similarly favorable prognosis. It is conceivable that after initial surgical resection a watch and wait type of approach is appropriate, even following partial resection. The role of upfront radiotherapy is uncertain and it should probably be left for progressive tumors.