Re-examining the optimal extent of lymph node dissection for colon cancer using the lymphadenectomy index.

The optimal extent of lymph node dissection in colon cancer surgery is specified in guidelines based on the results of past analyses. However, with advances in surgical techniques and multidisciplinary treatments, the clinical significance of dissecting each lymph node may change. In this study, we re-examined the optimal dissection range in each colon cancer localization. We retrospectively analyzed 788 cases of T1-T4 colon cancer who underwent radical resection between 2008 and 2018 at our hospital, and evaluated the Lymphadenectomy Index. No metastases to the main lymph node were found in T1 cases. In T2 cases, dissection effect to the main lymph node were observed in cases with tumors localized in the ascending colon and left side of the transverse colon. For tumors localized in the cecum, dissection was effective for lymph nodes in nodal station 213, in the right side of the transverse colon in station 211, in the descending colon in station 221, and in the sigmoid colon in station 231. These lymph nodes could have been considered out of scope for dissection if the Japanese guidelines were followed. In these cases, the extent of lymph node dissection should be carefully considered on a case-by-case basis.