Superiority of log odds of positive lymph nodes (LODDS) for prognostic prediction after gastric cancer surgery: a multi-institutional analysis of 7620 patients in China

Purpose To compare the 8th pN system with ratio-based and Log odds of positive lymph nodes (LODDS) staging systems for predicting the overall survival (OS) of gastric cancer (GC) patients after curative gastric resection. Methods We analyzed, retrospectively, clinicopathologic and prognostic data from three Chinese medical centers, on 7620 patients who underwent curative surgery for GC. We established a hypothetical tumor-LODDS-metastasis (TLM) and tumor-ratio-metastasis (TRM) staging system. The relative discriminative abilities of the different staging systems were assessed using Akaike’s Information Criterion (AIC), a linear trend chi-square test, and a likelihood ratio chi-square test. Results The cut-off points of the LODDS were set as: ≤ − 1.5, − 1.5 to − 1.0, − 1.0 to − 0.5, − 0.5 to 0, and > 0. There were significant differences in the survival of patients in different LODDS classifications for each pN or LNR group. When stratified by the LODDS classification, the prognosis was more homologous according to the pN or lymph-node ratio (LNR) classifications. The modified TLM staging system had better discriminatory ability and better optimistic prognostic stratification than the 8th TNM or the TRM staging systems for predicting the prognosis of patients with GC. Conclusions The LODDS staging system was superior to other lymph-node classifications for predicting the prognosis of patients undergoing gastrectomy GC. LODDS may be incorporated into a GC staging system if these results are confirmed by other studies.