The purpose of this bi‐institutional retrospective study was to determine whether survival for dogs with extremity osteosarcoma (OS) is improved through the use of stereotactic radiotherapy (SRT; a single fraction of 25 Gy, or 36 Gy total given in three consecutive daily fractions) plus chemotherapy, vs lower dose conventionally planned and delivered hypofractionated radiotherapy (CHRT; 14‐20 Gy total in 1‐2 consecutive daily fractions) plus chemotherapy. We also sought to determine whether baseline pain severity influences oncologic outcomes following radiotherapy for canine extremity OS. The medical records of 82 dogs undergoing radiotherapy for confirmed or presumed OS were reviewed. In dogs receiving combinations of both chemotherapy and radiotherapy, survival was significantly longer with SRT vs CHRT (median overall survival time: 350 vs 147 days; P = .031). In a univariate analysis, dogs with pulmonary metastases and high pain at the time of irradiation had short overall survival times; use of high radiation doses and chemotherapy were associated with improved survival. Separate multivariable models were built to assess the predictive nature of various factors that might influence event‐free or overall survival in dogs treated with radiotherapy, with or without chemotherapy; for dogs treated with both chemotherapy and radiotherapy, overall survival times were significantly longer when baseline pain scores were ‘low’ (vs ‘high’; hazard ratio: 0.258; P = .030), radiation doses were high (hazard ratio: 0.943; P = .034). Neither pain nor radiation dose were associated with survival in dogs treated with radiotherapy, without chemotherapy.

中文翻译：

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放疗剂量和治疗前疼痛水平对接受放疗联合或不联合化疗的犬的生存率的影响。

这项双机构回顾性研究的目的是确定是否通过使用立体定向放射治疗（SRT；单次 25 Gy 或 36 Gy 分次连续给药，每天分三次给予四肢骨肉瘤（OS）犬的存活率得到改善） ) 加化疗，与较低剂量的常规计划和提供的大分割放疗（CHRT；每天 1-2 次连续分次共 14-20 Gy）加化疗。我们还试图确定基线疼痛严重程度是否会影响犬四肢 OS 放疗后的肿瘤学结果。回顾了 82 只因确诊或推定 OS 而接受放疗的狗的医疗记录。在接受化疗和放疗联合治疗的狗中，SRT 与 CHRT 相比，生存时间明显更长（中位总生存时间：P = .031）。在单变量分析中，有肺转移和放疗时剧烈疼痛的狗的总生存时间较短；使用高辐射剂量和化疗与提高生存率有关。建立了单独的多变量模型来评估可能影响接受放疗（有或没有化学疗法）的犬的无事件或总体生存率的各种因素的预测性质；对于同时接受化疗和放疗的狗，当基线疼痛评分“低”（相对于“高”；风险比：0.258；P = .030）、放射剂量高（风险比：0.943；磷= .034）。在接受放疗、不接受化疗的狗中，疼痛和放疗剂量均与存活率无关。