Stereotactic radiosurgery for recurrent or unresectable pilocytic astrocytoma.
OBJECTIVE
To report the outcomes in patients with recurrent or unresectable pilocytic astrocytoma (PA) treated with Gamma Knife stereotactic radiosurgery (SRS).


METHODS
Retrospective review of 18 patients (20 lesions) with biopsy-confirmed PA having SRS at our institution from 1992 through 2005.


RESULTS
The median patient age at SRS was 23 years (range, 4-56). Thirteen patients (72%) had undergone one or more previous surgical resections, and 10 (56%) had previously received external-beam radiation therapy (EBRT). The median SRS treatment volume was 9.1 cm(3) (range, 0.7-26.7). The median tumor margin dose was 15 Gy (range, 12-20). The median follow-up was 8.0 years (range, 0.5-15). Overall survival at 1, 5, and 10 years after SRS was 94%, 71%, and 71%, respectively. Tumor progression (local solid progression, n = 4; local solid progression + distant, n = 1; distant, n = 2; cyst development/progression, n = 4) was noted in 11 patients (61%). Progression-free survival at 1, 5, and 10 years was 65%, 41%, and 17%, respectively. Prior EBRT was associated with inferior overall survival (5-year risk, 100% vs. 50%, p = 0.03) and progression-free survival (5-year risk, 71% vs. 20%, p = 0.008). Nine of 11 patients with tumor-related symptoms improved after SRS. Symptomatic edema after SRS occurred in 8 patients (44%), which resolved with short-term corticosteroid therapy in the majority of those without early disease progression.


CONCLUSIONS
SRS has low permanent radiation-related morbidity and durable local tumor control, making it a meaningful treatment option for patients with recurrent or unresectable PA in whom surgery and/or EBRT has failed.
Department of Radiation Oncology, Mayo Clinic, Rochester, MN, USA.
Christopher L
CL
Hallemeier
Bruce E
BE
Pollock
Paula J
PJ
Schomberg
Michael J
MJ
Link
Paul D
PD
Brown
Scott L
SL
Stafford
D000293:Adolescent; D000328:Adult; D001254:Astrocytoma / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy / Q000601:surgery*; D001929:Brain Edema / Q000209:etiology; D001932:Brain Neoplasms / Q000401:mortality / Q000532:radiotherapy / Q000601:surgery*; D002648:Child; D002675:Child, Preschool; D018450:Disease Progression; D018572:Disease-Free Survival; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy / Q000601:surgery*; D016634:Radiosurgery / Q000379:methods* / Q000401:mortality; D012189:Retrospective Studies; D016896:Treatment Outcome; D047368:Tumor Burden; D055815:Young Adult