Cyberknife Stereotactic Radiosurgery for Residual, Recurrent, and Metastatic Hemangiopericytomas: A Single-institution Experience

Introduction: Hemangiopericytomas are relatively rare vascular neoplasms deriving from Zimmermann pericytes on capillary walls. Treatment consists of gross total resection followed by adjuvant radiotherapy. Due to their dural sinus invasion, high vascularity, and anatomic inaccessibility, limitations occur in surgical approaches with potential for recurrence. Stereotactic radiosurgery (SRS) has been suggested to serve as a potential modality for postoperative adjuvant therapy. This study aims to present a long-term retrospective evaluation of the role of CyberKnife SRS in the management of residual, recurrent, and metastatic hemangiopericytomas in a single-institution experience.

Methods: We retrospectively reviewed the clinical and radiological outcomes of patients with histopathologically confirmed hemangiopericytomas treated with CyberKnife SRS at Stanford University Medical Center from 2009 to 2022. A total of 12 patients with 58 tumors underwent CK SRS for residual (17.2%), recurrent (50%), and metastatic (44.8%) hemangiopericytomas. The median patient age was 51 years (range: 40-85 years) at the time of CK treatment.

Results: The median follow-up period was 22 months (range: 3-74 months) and the median duration from surgery to SRS treatment was 59 months (range: 3-162 months). All patients had been previously treated with surgical resection. The median tumor volume was 1.2 cc (range: 0.02-179 cc) and the median marginal and maximum radiosurgical doses to the tumors were 20 Gy (range: 18-27 Gy) and 26.8 Gy (range: 22-37 Gy), respectively. Clinical and radiographical follow-up data were available for all tumors. Of the 58 tumors treated, 19 showed recurrence (32.8%) after CK therapy. The median time to recurrence was 23 months. The local tumor control (LTC) and the overall survival (OS) rates were 69.4% and 64.4% at 36-months, respectively.

Conclusion : CyberKnife SRS represents an effective and safe management option for residual, recurrent, and metastatic hemangiopericytomas. Postoperative SRS is an attractive treatment modality that increases time to recurrence as well as patient survival.