Purpose

Organ at risk (OAR) dose constraints are a critical aspect of SABR treatment planning. There is limited evidence supporting preferred dose constraints for many OARs. We sought to evaluate OAR dose constraints used in ongoing clinical trials of SABR for oligometastatic disease.

Methods and Materials

Clinicaltrials.gov was searched from inception to February 2020 to capture actively accruing clinical trials using SABR in oligometastatic disease. Dose constraints were obtained by contacting principal investigators and abstracted by 2 authors. Variability of constraints was assessed by comparing the width of the interquartile range and difference between the maximum and minimum dose to a volume.

Results

Fifty-three of 85 eligible clinical trials contributed OAR constraints used in analysis. Dose constraints for 1 to 8 fractions of SABR were collected for 33 OARs. Variability was found in the absolute allowable OAR doses, use of planning OAR volumes, and whether constraints were optional versus mandatory. For many OARs, modal dose constraints often matched a pre-existing publication, but no single pre-existing publication matched the modes of all OAR dose constraints. Organs displaying the most variability were the rectum, penile bulb, and chest wall and ribs. The esophagus, stomach, duodenum, and small bowel also indicated high variability for at least 1 constraint. OARs previously evaluated by HyTEC appeared to have less variability among study protocols.

Conclusions

We found substantial variability in OAR dose constraints used in current clinical trials evaluating SABR in oligometastatic disease. We are unable to comment on toxicity rates or acceptability of dose constraints used. Future research and recommendations for standardized OAR dose constraints, as well as consistency in implementing planning OAR volume margins, should be priorities for the field of radiation oncology.

中文翻译：

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SABR 中的器官风险剂量限制：积极临床试验的系统评价

目的

危及器官 (OAR) 剂量限制是 SABR 治疗计划的一个关键方面。支持许多 OAR 的首选剂量限制的证据有限。我们试图评估在正在进行的 SABR 治疗寡转移性疾病临床试验中使用的 OAR 剂量限制。

方法和材料

从开始到 2020 年 2 月，对 Clinicaltrials.gov 进行了搜索，以捕获使用 SABR 治疗寡转移性疾病的积极积累的临床试验。通过联系主要研究人员获得剂量限制，并由 2 位作者提取。通过比较四分位间距的宽度以及最大和最小剂量与体积之间的差异来评估约束的可变性。

结果

85 项符合条件的临床试验中有 53 项提供了用于分析的 OAR 限制。为 33 个 OAR 收集了 1 到 8 份 SABR 的剂量限制。在绝对允许的 OAR 剂量、计划 OAR 体积的使用以及约束是可选的还是强制的方面发现了可变性。对于许多 OAR，模态剂量限制通常与预先存在的出版物相匹配，但没有一个预先存在的出版物与所有 OAR 剂量限制的模式相匹配。表现出最大变异性的器官是直肠、阴茎球部、胸壁和肋骨。食道、胃、十二指肠和小肠也表明至少 1 个约束的高变异性。先前由 HyTEC 评估的 OAR 似乎在研究方案中的变异性较小。

结论

我们发现目前评估寡转移性疾病中 SABR 的临床试验中使用的 OAR 剂量限制存在很大差异。我们无法评论毒性率或所用剂量限制的可接受性。未来对标准化 OAR 剂量限制的研究和建议，以及实施规划 OAR 体积裕度的一致性，应该是放射肿瘤学领域的优先事项。