PC3 - 138 Stereotactic Radiosurgery for Intracranial Hemangiopericytomas – A Multicenter Study

Abstract

Hemangiopericytomas (HPC) are widely recognized for their aggressive clinical behavior. We report a large multicenter study, through the International Gamma Knife Research Foundation reviewing management and outcome following stereotactic radiosurgery (SRS) for recurrent or newly-discovered HPC’s. Methods: Eight centers participated, reviewing a total of 90 patients harboring 133 tumors. Prior treatments included embolization (n = 8), chemotherapy (n=2), and fractionated radiotherapy (n=34). The median tumor volume at the time of SRS was 4.9 ml (range 0.2-42.4 ml). WHO-grade II (typical) HPC’s formed 78.9% (n=71) of the cohort. The median margin and maximal doses delivered were 15 Gy (2.8-24) and 32 Gy (8-51), respectively. The median clinical and radiographic follow-up period was 59 months (6-190) and 59 months (6-183), respectively. Results: At last follow-up, 55% of tumors and 62.2% of patients demonstrated local tumor control. New remote intracranial tumors were found in 27.8%. 24.4% of patients developed extra-cranial metastases. Adverse radiation effects were noted in 6.7%. The overall survival was 91.5%, 82.1%, 73.9%, 56.7%, and 53.7% at 2, 4, 6, 8, and 10 years, respectively, after initial SRS. Local progression free survival was 81.7%, 66.3%, 54.5%, 37.2%, and 25.5% at 2, 4, 6, 8, and 10 years, respectively, after initial SRS. In our cohort, 32 patients underwent 48 repeat SRS procedures for 76 lesions. Margin dose greater than 16 Gy (p=0.037) and tumor histology (p=0.006) were shown to influence PFS. Conclusions: SRS provides a reasonable rate of local tumor control and a low risk of adverse effects