Canine soft tissue sarcoma (STS) has served as a preclinical model for radiation, hyperthermia, experimental therapeutics, and tumor microenvironmental research for decades. Stereotactic body radiotherapy (SBRT) demonstrates promising results for the control of various tumors in human and veterinary medicine; however, there is limited clinical data for the management of STS with SBRT. In this retrospective study, we aimed to define overall efficacy and toxicity of SBRT for the treatment of macroscopic canine STS to establish this preclinical model for comparative oncology research. Fifty-two canine patients met inclusion criteria. Total radiation dose prescribed ranged from 20–50 Gy delivered in 1–5 fractions. Median progression-free survival time (PFST) was 173 days and overall survival time (OST) 228 days. Best overall response was evaluable in 46 patients, with 30.4% responding to treatment (complete response n = 3; partial response n = 11). For responders, OST significantly increased to 475 days vs. 201 days (P = 0.009). Prognostic factors identified by multivariable Cox regressions included size of tumor and metastasis at presentation. Dogs were 3× more likely to progress (P = 0.009) or 3.5× more likely to experience death (P = 0.003) at all times of follow up if they presented with metastatic disease. Similarly, every 100-cc increase in tumor volume resulted in a 5% increase in the risk of progression (P = 0.002) and death (P = 0.001) at all times of follow up. Overall, 30.8% of patients developed acute toxicities, 7.7% grade 3; 28.8% of patients developed late toxicities, 11.5% grade 3. Increased dose administered to the skin significantly affected toxicity development. SBRT serves as a viable treatment option to provide local tumor control for canine macroscopic STS, particularly those with early-stage disease and smaller tumors. The results of this study will help to define patient inclusion criteria and to set dose limits for preclinical canine STS trials involving SBRT.

几十年来，犬软组织肉瘤 (STS) 一直是放射、热疗、实验治疗和肿瘤微环境研究的临床前模型。立体定向放射治疗 (SBRT) 在控制人类和兽医学中的各种肿瘤方面取得了可喜的成果；然而，关于 SBRT 治疗 STS 的临床数据有限。在这项回顾性研究中，我们旨在确定 SBRT 治疗肉眼可见的犬 STS 的整体疗效和毒性，以建立这种比较肿瘤学研究的临床前模型。五十二名犬类患者符合纳入标准。规定的总辐射剂量范围为 20-50 Gy，分 1-5 次给药。中位无进展生存时间 (PFST) 为 173 天，总生存时间 (OST) 为 228 天。在 46 名患者中可评估最佳总体反应，其中 30.4% 对治疗有反应（完全反应 n = 3；部分反应 n = 11）。对于响应者，OST 显着增加到 475 天与 201 天（P = 0.009）。多变量 Cox 回归确定的预后因素包括肿瘤的大小和就诊时的转移。如果狗出现转移性疾病，则在随访的所有时间里，狗进展的可能性增加 3 倍（P = 0.009）或死亡的可能性增加 3.5 倍（P = 0.003）。类似地，肿瘤体积每增加 100 cc 导致进展风险 ( P = 0.002) 和死亡 ( P= 0.001) 在所有随访时间。总体而言，30.8% 的患者出现急性毒性，7.7% 为 3 级；28.8% 的患者出现晚期毒性，11.5% 为 3 级。增加皮肤给药剂量显着影响毒性发展。SBRT 作为一种可行的治疗选择，为犬肉眼可见的 STS 提供局部肿瘤控制，尤其是那些患有早期疾病和较小肿瘤的 STS。这项研究的结果将有助于确定患者纳入标准，并为涉及 SBRT 的临床前犬 STS 试验设定剂量限制。