Index of estimated benefit from lymph node dissection for stage I-III transverse colon cancer: an analysis of the 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) × (5-year overall survival (OS) rate of the patients with LNM) × 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.