Volumetric Modulated arc Therapy (VMAT) based Stereotactic Radiotherapy (SRT) for canine adrenocortical tumors with vascular invasion



To evaluate the feasibility and efficacy of hypofractionated stereotactic volumetric modulated arc radiotherapy (HFS-VMAT RT) in treating canine adrenal tumours with vascular invasion.


A single-arm clinical study was performed. The dogs underwent total body computed tomography (CT), brain and abdomen magnetic resonance imaging (MRI) and endocrine assay. Adrenal masses were classified as cortisol secreting adrenal tumour (CSAT) o non-secreting adrenal tumour (NSAT). RT treatments were delivered by HFS-VMAT via a linear accelerator (LINAC). The overall survival was estimated by the Kaplan-Meier method. The overall response and radio-toxicity effects were evaluated.


Nine dogs were enrolled. Three dogs were affected by CSATs and the remaining dogs had NSATs. The prescribed doses ranged from 30 to 45 Gy in three or five consecutive daily fractions. The median overall survival time was 1030 days, with 2 subjects censored (1632 and 1592 days after SRT). The overall mean reduction of the dorso-ventral diameter and volume were, respectively, 31.59 ± 7.45% and 30.60 ± 7.96%. The endocrine profile normalized in two dogs with CSATs. Radio-toxicities were mild and self-limiting. Seven deaths were recorded during the follow-up period and two dogs were censored. The median survival time was 1030 days.

Clinical significance:

HFS-VMAT RT should be considered as a feasible and effective therapeutic option for adrenal tumours when vascular invasion is present.

Accepted for publication on 

Journal of Small Animal Practice