CyberKnife stereotactic radiotherapy for treatment of primary intracranial tumors in dogs.

Background: Limited data exist about the use, efficacy, and prognostic factors influencing outcome when CyberKnife is used to treat dogs with intracranial neoplasia.

Objectives: To determine the prognosis and associated prognostic factors for dogs that were imaged, determined to have primary intracranial tumors, and treated with CyberKnife radiotherapy.

Animals: Fifty-nine dogs treated with CyberKnife radiotherapy for primary intracranial tumors.

Methods: Retrospective medical record review of cases from January 2010 to June 2016. Data extracted from medical records included signalment, weight, seizure history, tumor location, tumor type (based on imaging), gross tumor volume, planned tumor volume, treatment dates, radiation dose, recurrence, date of death, and cause of death.

Results: The median progression-free interval (PFI) was 347 days (range 47 to 1529 days), and the median survival time (MST) was 738 days (range 4 to 2079 days). Tumor location was significantly associated with PFI when comparing cerebrum (median PFI 357 days; range 47-1529 days) versus cerebellum (median PFI 97 days; range 97-168 days) versus brainstem (median PFI 266 days; range 30-1484 days), P = .03. Additionally, the presumed tumor type was significantly associated with MST (P < .001).

Conclusions And Clinical Importance: Use of Cyberknife and SRT might improve MST, compared with RT, in dogs with intracranial neoplasia.