Determinants of Lymph Node Yield and Involvement in Resectable Colon Cancer: A Study of Anatomical, Pathological, and Fresh, Nonfixed Specimen Dissection

The objective of this study is to assess the success of lymph nodal harvest, extent of nodal spread in pericolic and apical stations, and factors affecting nodal metastasis in freshly resected colon cancer specimens. Following surgery, the lymph nodes were dissected off the specimen in the presence of an onco-pathologist. Apical lymph nodes were stationed according to “Japanese society of nodal classification for colon and rectum,” and pericolic lymph nodes were put into zones, proximally and distally, according to the distances from the tumor epicenter. Pathological analysis was done to see the pattern of nodal spread. Age, sex, T-stage, grade, and lymphovascular invasion (LVI) had no significant association with total lymph nodal yield. The chance of finding positive pericolic lymph nodes within proximal and distal 5 cm ( p = 0.002 vs. p = 0.011) and proximal 5 to 10 cm ( p = 0.010) of the tumor was significantly high. Beyond 10 cm proximal and 5 cm distal of the tumor epicentre, there were no pericolic positive nodes. Apical lymph nodal harvest rate was 74.64%, and positivity rate was 7% (5 out of 71). T-stage, grade, lymphovascular invasion (LVI), and perineural invasion (PNI) have statistically significant association with pericolic and apical node metastasis. In the fresh colonic specimen, pericolic nodal positivity beyond 10 cm proximal and 5 cm distal of tumor epicenter is rare. Apical and pericolic lymph node positivity is highly dependent upon multiple clinicopathological factors like T-stage, grade, and the presence of LVI and PNI. The lymph nodal yield is much better in fresh specimens by a surgeon under the supervision of a pathologist than fixed specimen. Trial Registered under Clinical Trials Registry-India (CTRI), REF/2019/05/025631.