"Standardizing the Definition of Each Colon Cancer Segment: Delphi Consensus"

Reviewed by

Reza Lankarani

M.D

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Diseases of the Colon & Rectum

DOI: 10.1097/DCR.0000000000003739

Published online:June 2025

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This international Delphi consensus study addresses a critical gap in colorectal oncology: the lack of standardized anatomical definitions for colon cancer segments. Its primary strength lies in its rigorous methodology and global representation. The three-round Delphi process engaged 295 colorectal surgery experts from 28 countries across four continents, ensuring diverse perspectives and high retention rates (91% completed round 2; 89% all three rounds). The structured approach—using a 9-point Likert scale, predefined consensus thresholds (≥70% for strong agreement), iterative refinement, and a final consensus conference—enhances the validity and reliability of the findings. The resulting definitions leverage clinically accessible landmarks (e.g., ileocecal valve for cecum, disappearance of teniae for sigmoid colon) and introduce a practical "10-cm rule" for flexure boundaries, balancing anatomical precision with surgical applicability. Crucially, the study clarifies responsibility: surgeons should define tumor location intraoperatively (98% consensus), challenging current ICD coding priorities.

However, the study also reveals persistent challenges requiring further resolution. While strong consensus (>90%) was achieved for 7/8 colon segments (cecum to sigmoid), significant geographical discordance emerged regarding the rectosigmoid concept. Experts from the Americas/Europe overwhelmingly supported abolishing the term (75-76% consensus), favoring classification as upper rectal cancer, whereas Asian experts favored retaining it (63% consensus), reflecting entrenched regional guidelines (e.g., Japanese classifications). Additionally, defining overlapping segment tumors achieved only moderate consensus (64%), with the "center of the lesion" approach lacking universal endorsement. These discrepancies highlight the influence of regional practices and underscore that anatomical definitions alone may not resolve all clinical dilemmas, particularly where embryological boundaries (e.g., hindgut vs. midgut) influence treatment paradigms. Future validation correlating these definitions with oncologic outcomes is essential.

Over۷all, this study provides a much-needed, methodologically robust foundation for standardizing colon segment definitions globally, enhancing registry data comparability and research validity. Its key limitation is unresolved regional divergence on the rectosigmoid junction and overlapping lesions, indicating areas for targeted interdisciplinary research integrating anatomical, molecular, and outcome data.

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Reza Lankarani

M.D

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