Surgery Resident NorthstarVETS Lumberton, New Jersey
Soft tissue sarcomas (STS) are common in dogs and are typically found on the extremities. Postoperative radiotherapy is employed to eliminate residual microscopic disease, and use of a liquid fiducial marker could allow more precise treatment delivery. The objective of this prospective study was to evaluate clinical outcome in dogs receiving single, high dose radiotherapy following marginal or microscopically incomplete resection of STS.
Dogs with grade 2 or 3 STS that underwent single fraction, 20Gy stereotactic radiotherapy (SRT) following excision were included. Acute and delayed toxicities were scored based on published criteria. Overall survival time (OST) and disease-free interval (DFI) were determined. Thirty-nine dogs were included. Acute or delayed toxicities occurred in 82% and 33% of dogs respectively. Tumors recurred locally in 9/39 (23%) dogs. The restricted mean OST and DFI were 1409.8 days and 1246 days respectively. Median OST and DFI were not reached. Dogs in this study that received postoperative fiducial-guided SRT had prolonged restricted mean OST and DFI compared to previous studies. The incidence of treatment-related toxicity was similar to a previous report in which a majority of dogs undergoing radiotherapy experienced self-limiting grade 1 or 2 acute toxicities. Limitations of the current study include small sample size, imprecise definition of tumor resection cavities, and exclusion of dogs with reconstructive scars or likelihood of excessive motion in the treatment field. Postoperative single fraction SRT achieves good local tumor control in dogs with grade 2 and 3 STS, while limiting the number of anesthetic episodes and owner costs.
