Single high-dose radiation therapy and liquid fiducial markers can be used in dogs with incompletely resected soft tissue sarcomas.

OBJECTIVE: To evaluate the outcome and effects of single high-dose radiation therapy with the aid of liquid fiducial markers in dogs following resection of soft tissue sarcomas (STSs). ANIMALS: 36 client-owned dogs. METHODS: Dogs with a histologic diagnosis of a grade II or III STS that underwent liquid fiducial guided single fraction, 20-Gy stereotactic radiation therapy following surgical excision of an STS between May 2017 and March 2019 were prospectively enrolled in this study. Data collected from the medical records included patient signalment, tumor-related information, treatment details, and outcome. Kaplan-Meier survival analysis was performed for overall survival time (OST) and disease-free interval (DFI). The median OST and DFI were not reached, so restricted mean OST and DFI were also calculated. RESULTS: 36 dogs were included in the study. All dogs underwent radiation therapy a mean of 36.1 days (range, 20 to 59 days) after surgery. Acute and delayed radiation toxicity effects occurred in 80.5% and 36.1% of dogs, respectively, all of which affected the skin. Tumor recurrence was noted in 24.3% of dogs with a median time to recurrence of 272 days (range, 14 to 843 days). The restricted mean OST was 1,556 days (range, 1,383 to 1,728 days) and restricted mean DFI was 1,330 days (range, 1,101 to 1,559 days). CLINICAL RELEVANCE: The results of this study showed that administering a single 20-Gy fraction of radiation in combination with a liquid fiducial marker to treat marginally or incompletely resected STS in the absence of gross disease resulted in similar OST and DFI compared to other previously reported radiation protocols.

Use of CT and MR imaging in radiation therapy planning of imaging-diagnosed canine intracranial meningioma achieves better tumor coverage than CT alone.

The aim of this retrospective, secondary analysis study was to quantify the dosimetric impact of the lack of interobserver agreement on gross tumor volume (GTV) delineation for canine meningioma. This study used a previously reported population of 13 dogs with GTVs contoured on CT alone and on registered CT-MR by 18 radiation oncologists. The "true" GTV was generated for each dog using a simultaneous truth and performance-level estimation algorithm, and "true" brain was defined as the whole brain minus true GTV. Treatment plans were generated for each dog and observer combination, using criteria applied to the observer's GTV and brain contours. Plans were then categorized as a pass (met all planning criteria for true GTV and true brain) or fail. A mixed-effects linear regression was performed to examine differences in metrics between CT and CT-MR plans and mixed-effects logistic regression was performed to examine differences in percentages of pass/fail between CT and CT-MRI plans. The mean percent coverage of true GTV by prescribed dose was higher for CT-MR plans than for CT plans (mean difference 5.9%; 95% CI, 3.7-8.0; P < 0.001). There was no difference in the mean volume of true brain receiving ≥24 Gy and in maximum true brain dose between CT plans and CT-MR plans (P ≥ 0.198). CT-MR plans were significantly more likely to pass the criteria for true GTV and true brain than CT plans (OR 1.75; 95% CI, 1.02-3.01; P = 0.044). This study demonstrated significant dosimetric impact when GTV contouring was performed on CT alone compared with CT-MR.

Intratumoral bleomycin and IL-12 electrochemogenetherapy for treating head and neck tumors in dogs.

Bleomycin and Interleukin 12 have been used clinically to treat tumors; however, the co-administration of Bleomycin and Interleukin 12 followed by electroporation has not been tested clinically. In this study, dogs with spontaneous head and neck tumors were treated with one co-administration of Bleomycin and Interleukin 12 plasmid DNA followed by electroporation. The regression of the recurrent papillary tumor and the adjacent metastatic bone tumor was analyzed by multiple CT scans. The papillary tumor was completely eradicated in less than 2 weeks, and the bone tumor was not visible 23 weeks after the administration.