Optimal Indication of <scp>D3</scp> Lymph Node Dissection for Non‐Metastatic Colon Cancers by Tumor Stages: Evaluation of Therapeutic Value Index for Each Lymph Node Station

ABSTRACT Aims To explore the therapeutic impact of D3 lymph node dissection for non‐metastatic colon cancers, evaluating the therapeutic value index for each lymph node station according to surgical stages. Methods Consecutive patients with surgical Stage I–III colon and rectosigmoid cancer who underwent curative resection between January 2003 and December 2014 were identified from the Japanese Society for Cancer of the Colon and Rectum database and analyzed. The therapeutic value index (TVI) was defined as the incidence of lymph node metastasis times 5‐year overall survival and calculated for each nodal station stratified by tumor stages. Results A total of 21 914 patients, including 9583 patients with right‐sided colon cancer and 12 331 with left‐sided colon cancer, were eligible for analysis. In right‐sided colon cancer, reflecting differences in tumor location and the presence of the right colic artery, variability in the TVIs was observed among stations #203 to #223. When the three stations were collectively considered as a single group of main lymph nodes, the combined TVIs for sT1Nany, sT2N0, sT2Nany, sT3‐4 N0, and sT3‐4Nany were 0.630, 0.493, 0.857, 0.849, and 2.274, respectively. For station #253 in left‐sided colon cancers, the TVIs for sT1Nany, sT2N0, sT2Nany, sT3‐4 N0, and sT3‐4Nany were 0.120, 0.278, 0.634, 0.475, and 1.234, respectively. Conclusion Within a D3‐treated cohort stratified by surgical stage, the TVI of the main lymph nodes for sT2N0 tumors remained low, approximating that of sT1Nany rather than sT2Nany or sT3‐4 tumors. Further evaluation of the therapeutic impact of D3 lymphadenectomy for clinically node‐negative T2 colon cancer is warranted.