Comparison of Survival After Treatment of Presumed Intracranial Meningioma by Radiotherapy or Surgery in 285 Dogs

ABSTRACT Background The comparative effectiveness of radiotherapy and surgery for treating intracranial meningioma is unknown. Objectives To compare survival after treatment of suspected intracranial meningioma by either surgery or radiotherapy. Animals Two hundred eighty‐five companion dogs with suspected intracranial meningiomas presenting to 11 specialty clinics in three countries. Methods Parallel cohort comparison study on retrospective data. Dogs diagnosed with intracranial meningioma by board‐certified veterinary neurologists or radiologists and treated by radiotherapy or surgery were identified through medical record searches and presenting and survival data extracted. Lesion site was classified as rostro‐ or caudotentorial and size was measured on contrast magnetic resonance images. Outcome was all‐cause death. Analysis of survival by Cox proportional hazards, including selection for optimal multivariable model using lasso, counterfactual modeling including variables associated with treatment allocation and survival. Results One hundred sixty‐eight dogs received radiotherapy and 117 received surgery. All analyses indicated reduced survival associated with surgery compared to radiotherapy. There was a median survival after surgery of 297 (IQR: 99–768) days compared with 696 (IQR: 368–999) for dogs treated by radiation, associated with a univariable hazard ratio of 1.802 (95% CI: 1.357–2.394). Counterfactual modeling estimated a mean survival of 480 (95% CI: 395–564) days after surgery and 673 (95% CI: 565–782) days after radiotherapy, representing a decrease in survival of 29%. Location and size of the lesion were not associated with survival duration. Conclusions and Clinical Importance Dogs with suspected intracranial meningioma have substantially superior survival after radiotherapy compared to surgery.