Department of Pulmonology, Maastricht University Medical Center+, the Netherlands.
Department of Radiation Oncology (Maastro Clinic), GROW School for Oncology and Developmental Biology, Maastricht University Medical Center+, the Netherlands.
Radiother Oncol. 2021 Dec;165:8-13. doi: 10.1016/j.radonc.2021.10.007. Epub 2021 Oct 18.
The definition of the clinical target volume (CTV) for post-operative radiotherapy (PORT) for thymoma is largely unexplored. The aim of this study was to analyze the difference in CTV delineation between radiation oncologists (RTO) and surgeons.
This retrospective multi-center study enrolled 31 patients who underwent PORT for a thymoma from five hospitals. Three CTVs were delineated per patient: one CTV by the RTO, one CTV by the surgeon (blinded to the results of the RTO) and a joint CTV after collaboration. Volumes (cm), Hausdorff distances (HD) and Dice similarity coefficients (DSC) were analyzed.
RTO delineated significantly bigger CTVs than surgeons (mean: 93.9 ± 63.1, versus 57.9 ± 61.3 cm, p = 0.003). Agreement was poor between RO and surgeons, with a low mean DSC (0.34 ± 0.21) and high mean HD of 4.5 (±2.2) cm. Collaborative delineation resulted in significantly smaller volumes compared to RTO (mean 57.1 ± 58.6 cm, p < 0.001). A mean volume of 18.9 (±38.1) cm was included in joint contours, but missed by RTO. Conversely, a mean volume of 55.7 (±39.9) cm was included in RTO's delineations, but not in the joint delineations.
To the best of our knowledge, this is the first study investigating CTV definition in thymoma. We demonstrated a significant variability between RTO and surgeons. Joint delineation prompted revisions in smaller CTV as well as favoring the surgeons' judgement, suggesting that surgeons provided relevant insight into other risk areas than RTO. We recommend a multidisciplinary approach to PORT for thymomas in clinical practice.
胸腺癌术后放疗（PORT）的临床靶区（CTV）定义在很大程度上尚未得到探索。本研究旨在分析放射肿瘤学家（RTO）和外科医生之间 CTV 勾画的差异。
这是一项回顾性多中心研究，共纳入来自五家医院的 31 例接受 PORT 治疗的胸腺癌患者。每位患者勾画了三个 CTV：一个由 RTO 勾画，一个由外科医生（不了解 RTO 的结果）勾画，一个在合作后共同勾画。分析了体积（cm）、Hausdorff 距离（HD）和 Dice 相似系数（DSC）。
RTO 勾画的 CTV 明显大于外科医生（平均：93.9±63.1cm，vs 57.9±61.3cm，p=0.003）。RTO 和外科医生之间的一致性较差，平均 DSC 较低（0.34±0.21），平均 HD 较高（4.5±2.2）cm。与 RTO 相比，合作勾画的体积明显较小（平均 57.1±58.6cm，p<0.001）。联合轮廓中包含 18.9（±38.1）cm 的平均体积，但 RTO 未包含。相反，RTO 勾画的体积中包含 55.7（±39.9）cm 的平均体积，但不在联合勾画中。
据我们所知，这是第一项研究胸腺癌 CTV 定义的研究。我们发现 RTO 和外科医生之间存在显著差异。联合勾画促使 CTV 体积缩小，并倾向于外科医生的判断，表明外科医生对 RTO 以外的其他风险区域提供了相关见解。我们建议在临床实践中采用多学科方法进行胸腺癌 PORT。
