Interobserver variability in target volume delineation in definitive radiotherapy for thoracic esophageal cancer: a multi-center study from China

• Published in: Radiation oncology (London, England) Vol. 16; no. 1; pp. 1 - 102
• Main Authors: Chang, Xiao, Deng, Wei, Wang, Xin, Zhou, Zongmei, Yang, Jun, Guo, Wenling, Liu, Miaoling, Qi, Xiaolu, Li, Ling, Zhang, Kaixian, Zhang, Min, Shi, Yonggang, Liu, Ke, Zhao, Yidian, Wang, Huitao, Yu, Zhilong, Zhang, Jihong, Wang, Lihua, Qiao, Xueying, Han, Chun, Zhu, Shuchai, Zhang, Ruohui, Chen, Junqiang, Hu, Cairong, Zhang, Fuquan, Hou, Xiaorong, Pang, Qingsong, Zhang, Wencheng, Li, Gaofeng, Lin, Hailei, Sun, Xinchen, Ge, Xiaolin, Li, Caihong, Ge, Hong, Li, Dingjie, Wang, Yadi, Lu, Na, Gao, Xianshu, Qin, Shangbin, Tian, Yuan, Xiao, Zefen
• Format: Journal Article
• Language: English
• Published: London BioMed Central Ltd 09.06.2021; BioMed Central; BMC
• Subjects: Cancer; Cancer of the esophagus; Cancer therapies; Care and treatment; Consistency; Contouring; Contours; Delineation; Development and progression; Dose-response relationship (Biochemistry); Esophageal cancer; Esophagus; Interobserver variability; Lymphatic system; Metastasis; Methods; Patient outcomes; Radiation therapy; Radiotherapy; Target volume delineation; Thorax; Tumors; Variability; China
• ISSN: 1748-717X; 1748-717X
• DOI: 10.1186/s13014-020-01691-4

Abstract Purpose To investigate the interobserver variability (IOV) in target volume delineation of definitive radiotherapy for thoracic esophageal cancer (TEC) among cancer centers in China, and ultimately improve contouring consistency as much as possible to lay the foundation for multi-center prospective studies. Methods Sixteen cancer centers throughout China participated in this study. In Phase 1, three suitable cases with upper, middle, and lower TEC were chosen, and participants were asked to contour a group of gross tumor volume (GTV-T), nodal gross tumor volume (GTV-N) and clinical target volume (CTV) for each case based on their routine experience. In Phase 2, the same clinicians were instructed to follow a contouring protocol to re-contour another group of target volume. The variation of the target volume was analyzed and quantified using dice similarity coefficient (DSC). Results Sixteen clinicians provided routine volumes, whereas ten provided both routine and protocol volumes for each case. The IOV of routine GTV-N was the most striking in all cases, with the smallest DSC of 0.37 (95% CI 0.32–0.42), followed by CTV, whereas GTV-T showed high consistency. After following the protocol, the smallest DSC of GTV-N was improved to 0.64 (95% CI 0.45–0.83, P  = 0.005) but the DSC of GTV-T and CTV remained constant in most cases. Conclusion Variability in target volume delineation was observed, but it could be significantly reduced and controlled using mandatory interventions.