Retrospective Study
Copyright ©The Author(s) 2022. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastrointest Oncol. May 15, 2022; 14(5): 1027-1036
Published online May 15, 2022. doi: 10.4251/wjgo.v14.i5.1027
Improving the accuracy and consistency of clinical target volume delineation for rectal cancer by an education program
Yang-Zi Zhang, Xiang-Gao Zhu, Ma-Xiaowei Song, Kai-Ning Yao, Shuai Li, Jian-Hao Geng, Hong-Zhi Wang, Yong-Heng Li, Yong Cai, Wei-Hu Wang
Yang-Zi Zhang, Xiang-Gao Zhu, Ma-Xiaowei Song, Kai-Ning Yao, Shuai Li, Jian-Hao Geng, Hong-Zhi Wang, Yong-Heng Li, Yong Cai, Wei-Hu Wang, Department of Radiation Oncology, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Peking University Cancer Hospital & Institute, Beijing 100142, China
Author contributions: Zhang YZ drafted the manuscript, and was involved with data analysis; Zhu XG, Yao KN, Li S, and Geng JH participated in the collection and analysis of the data; Song MX, Wang HZ, and Li YH revised the article critically for important intellectual content; Wang WH and Cai Y participated in the design of the study and revision of the article; and all authors read and approved the final manuscript.
Supported by the Beijing Municipal Science & Technology Commission, No. Z181100001718192; the Capital’s Funds for Health Improvement and Research, No. 2020-2-1027 and No. 2020-1-4021; the National Natural Science Foundation, No. 82073333; and the Beijing Natural Science Foundation, No. 1212011.
Institutional review board statement: This study was reviewed and approved by the Beijing Cancer Hospital Research Ethics Committee (Approval No. 2021YJZ111).
Informed consent statement: The participants of the study were not required to give informed consent to the study because the analysis used anonymous image data that were obtained from the education program.
Conflict-of-interest statement: The authors declare that there is no conflict of interest.
Data sharing statement: The datasets used and/or analyzed during the current study are available from the corresponding authors on reasonable request.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: https://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Wei-Hu Wang, MD, Chief Physician, Department of Radiation Oncology, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Peking University Cancer Hospital & Institute, No. 52 Fucheng Road, Haidian District, Beijing 100142, China. wangweihu88@163.com
Received: December 10, 2021
Peer-review started: December 10, 2021
First decision: January 12, 2022
Revised: January 24, 2022
Accepted: April 24, 2022
Article in press: April 24, 2022
Published online: May 15, 2022
Processing time: 150 Days and 19.3 Hours
Abstract
BACKGROUND

Accurate target volume delineation is the premise for the implementation of precise radiotherapy. Inadequate target volume delineation may diminish tumor control or increase toxicity. Although several clinical target volume (CTV) delineation guidelines for rectal cancer have been published in recent years, significant interobserver variation (IOV) in CTV delineation still exists among radiation oncologists. However, proper education may serve as a bridge that connects complex guidelines with clinical practice.

AIM

To examine whether an education program could improve the accuracy and consistency of preoperative radiotherapy CTV delineation for rectal cancer.

METHODS

The study consisted of a baseline target volume delineation, a 150-min education intervention, and a follow-up evaluation. A 42-year-old man diagnosed with stage IIIC (T3N2bM0) rectal adenocarcinoma was selected for target volume delineation. CTVs obtained before and after the program were compared. Dice similarity coefficient (DSC), inclusiveness index (IncI), conformal index (CI), and relative volume difference [ΔV (%)] were analyzed to quantitatively evaluate the disparities between the participants’ delineation and the standard CTV. Maximum volume ratio (MVR) and coefficient of variation (CV) were calculated to assess the IOV. Qualitative analysis included four common controversies in CTV delineation concerning the upper boundary of the target volume, external iliac area, groin area, and ischiorectal fossa.

RESULTS

Of the 18 radiation oncologists from 10 provinces in China, 13 completed two sets of CTVs. In quantitative analysis, the average CTV volume decreased from 809.82 cm3 to 705.21 cm3 (P = 0.001) after the education program. Regarding the indices for geometric comparison, the mean DSC, IncI, and CI increased significantly, while ΔV (%) decreased remarkably, indicating improved agreement between participants’ delineation and the standard CTV. Moreover, an 11.80% reduction in MVR and 18.19% reduction in CV were noted, demonstrating a smaller IOV in delineation after the education program. Regarding qualitative analysis, the greatest variations in baseline were observed at the external iliac area and ischiorectal fossa; 61.54% (8/13) and 53.85% (7/13) of the participants unnecessarily delineated the external iliac area and the ischiorectal fossa, respectively. However, the education program reduced these variations.

CONCLUSION

Wide variations in CTV delineation for rectal cancer are present among radiation oncologists in mainland China. A well-structured education program could improve delineation accuracy and reduce IOVs.

Keywords: Rectal cancer; Radiotherapy; Clinical target volume; Delineation; Interobserver variation; Education

Core Tip: Accurate clinical target volume (CTV) delineation is essential to ensure appropriate tumor control while minimizing the exposure of surrounding normal tissues. However, a large degree of variation in CTV delineation for rectal cancer still exists, despite the availability of several CTV delineation guidelines. Our study aimed to evaluate the impact of an education program on CTV delineation for rectal cancer. The results first confirmed the wide variations in CTV delineation for rectal cancer among radiation oncologists from mainland China and proved that a well-structured education program could improve the accuracy and consistency of delineation.