Index of estimated benefit from lymph node dissection for stage I-III transverse colon cancer: an analysis of the JS']JSCCR database

Purpose Main lymph node metastasis (LNM) dissection of transverse colon (TC) cancer is a difficult surgical procedure. Nonetheless, the main LNM ratio and the benefit of main lymph node (LN) dissection in TC cancer were unclear. This study aimed to identify high-risk patients for LNM and to evaluate the benefit of LN dissection in TC cancer. Methods Data for 26,552 colorectal cancer patients between 2007 and 2011 were obtained from the JSCCR database. Of these, 871 stage I-III TC cancer patients underwent surgery with radical LN dissection. These patients were evaluated using the index of estimated benefit from lymph node dissection (IEBLD), where IEBLD = (LNM ratio of each LN station) x (5-year overall survival (OS) rate of the patients with LNM) x 100. Results None of the patients with depth of invasion pT1-2 had main LNM. The presence of main LNM was associated with depth of invasion pT4, CEA-4H (carcinoembryonic antigen 4 times higher than preoperative cutoff value), or type 3, and 323 patients (37.1%) who had these factors were high-risk patients for main LNM. In these high-risk patients, the LNM ratio, 5-year OS rate of patients with LNM and IEBLD values, respectively, were 43.9%, 70.3%, and 30.5 for the pericolic LN; 20.3%, 66.0%, and 15.1 for the intermediate LN; and 9.6%, 58.5%, and 5.6 for the main LN. Conclusion Main LNM is associated with depth of invasion pT4, CEA-4H, or type 3. The IEBLD for the main LN of high-risk TC cancer patients was over 5.