Proposal of a new classification system for complete mesocolic excison in right-sided colon cancer

Although complete mesocolic excision has been performed for 10 years there remains no published prospective data. The lack of a classification which includes completeness of mesocolic tissue removal as well as plane of surgery contributes to the problem of comparing studies. The aim of the present study was to develop such a classification for right hemicolectomy.

In a prospective, non-randomized trial we collected specimens of right hemicolectomies from 38 German hospitals between February 2012 and October 2016. The degree of radicality of resection was reported. Photographs were taken of the specimens. After screening the images it became apparent that the specimens could be divided into four main groups according to the degree of missing mesocolic tissue, and three subgroups reflecting the plane of surgery.

Of 1373 patients 1097 images were available. Grading was possible in 1077 (98.2%). Distribution was Type 0 (best) 38.6%, Type I 43.3%, Type II 8.5%, Type III (poorest) 7.8%. Surgery was considered to be in a suboptimal plane of surgery in 15.2% overall, highest in Type III (37%) and lowest in Type 0 (7.8%, p < 0.001).

The proposed classification may be a relevant tool for the further investigation of CME for right colon cancer because it allows us to differentiate the aspects of lymphadenectomy and the preservation of the integrity of the mesocolon.