Standardization before radicality: Current evidence for complete mesocolic excision

Despite the ongoing discussion around complete mesocolic excision (CME) during right colectomy, it remains a poorly defined concept, and its oncologic role in the treatment of right-sided colon cancer remains unclear. Since its original description, CME has been interpreted inconsistently, with multiple techniques and definitions used across studies. This heterogeneity, combined with a reliance on retrospective and observational data, has limited the meaningful assessment of efficacy.

This narrative literature review aimed to summarize recent data evaluating the oncologic efficacy of CME for right-sided colon cancer. Relevant literature was identified through PubMed/MEDLINE searches using combinations of keywords including "complete mesocolic excision," "central vascular ligation," "D3 lymphadenectomy," and "right hemicolectomy." Particular emphasis was placed on prospective randomized trials.

Most studies reporting improved outcomes after CME have compared it with inadequately defined "conventional" colectomy, often using historical controls in whom the quality of mesocolic dissection, vascular ligation, and lymphadenectomy was unclear. Consequently, it is difficult to determine whether the observed benefits are attributable to more radical central (D3) lymphadenectomy or, perhaps more plausibly, to improved standardization and overall surgical quality in a procedure that traditionally has not been centralized to specialized colorectal units. The Radical Extent of Lymphadenectomy of Laparoscopic Right Colectomy (RELARC) trial for colon cancer provides the first high-quality randomized evidence addressing this issue. With standardized, high-quality surgery in both arms, RELARC demonstrated no significant difference in disease-free or overall survival at either 3 or 5 years between D2 dissection and D3/CME dissection.

Contemporary data support moving away from imprecise terminology, such as "CME," and toward explicit descriptions of lymphadenectomy extent. High-quality D2 dissection should be regarded as the standard of care for routine right colectomy, with future efforts prioritizing standardization, training, and quality improvement, while refining indications for selective D3 dissection in selected patients.