Log odds of positive lymph nodes in colon cancer: a meaningful ratio-based lymph node classification system

Background The log odds of positive lymph nodes (LODDS), defined as the log of the ratio between the numbers of positive and negative lymph nodes, has recently been proposed as a new prognostic index in surgical oncology. The aim of the present study was to investigate whether the LODDS system of lymph node classification was a more accurate prognostic tool than the tumor node metastasis (TNM) and lymph node ratio (LNR) classifications in colon cancer patients.Materials and methods Clinicopathologic data from 258 colon cancer patients who had undergone surgical resection were reviewed. Lymph node parameters were categorized according to the Internation Union Against Cancer/American Joint Cancer Commission (UICC/AJCC) TNM staging system, the LNR (LNR0 with ratio <= 0.05, LNR1 with 0.05 < ratio <= 0.20, LNR2 with ratio > 0.20), and the log odds ratio (LODDS0 <= -1.36, -1.36 < LODDS1 <= -0.53, and LODDS2 > -0.53).Results The LODDS was able to identify patients who would have been included in different prognostic categories, according to both the TNM and LNR. In addition, LODDS was significantly related to the number of positive and negative lymph nodes, as well as the number of examined lymph nodes. In multivariate analysis, LODDS classification (LODDS0: HR 1; LODDS1: HR 3.687, p = 0.003; LODDS2: HR 9.440, p < 0.001) was identified as an independent prognostic factor.Discussion The LODDS system is a highly reliable staging system with strong predictive ability for patient outcome. Compared with other nodal staging systems, the prognostic power of LODDS is less influenced by the number of lymph nodes dissected and examined.