Retrospective Analysis of Survival and Adverse Effects Associated With Stereotactic Body Radiation Therapy in 12 Dogs...

This retrospective analysis evaluated 12 dogs with hepatocellular carcinoma (HCC) who received stereotactic body radiation therapy (SBRT). Dogs received between 6 and 25 Grey (Gy) per fraction for 1-5 fractions for a total dose of 13-30 Gy. Eleven patients (92%) experienced acute adverse effects (AE), with the majority being VRTOG grade 2-3 stomach/small intestinal AE. Additionally, 70% of patients experienced late AE, with the majority being VRTOG grade 2 stomach/small intestinal AE. Liver-specific side effects were also observed following SBRT, including VCOG-CTCAE grade 4 hepatic encephalopathy and grade 5 liver failure. There was a statistically significant correlation between the gross tumour volume (GTV) and the overall survival time (OST; p = 0.02) as well as a significant correlation between the percentage of normal liver affected by the mass and the severity of acute stomach/small intestinal AE (p = 0.01). Statistically significant correlations were observed between the dose of radiation to the normal liver, starting with a threshold dose of 7 Gy, and an increase of the liver enzyme ALT. Median survival time (MST) of the cohort was 301 days. Dogs with > 28.7% of the liver affected by the mass had a MST of 182 days vs. 419 days for dogs with < 28.7% affected (p = 0.009). This study suggests parameters for GTV, percentage of liver affected, and dose to normal liver could affect survival and the likelihood for adverse effects and liver enzyme elevation when treating with SBRT.