The log odds of negative lymph nodes/T stage: a new prognostic and predictive tool for resected gastric cancer patients

PURPOSE: When only the TNM classification is used to predict survival in gastric cancer (GC) patients, the impact of the degree of lymphadenectomy on the prognosis is neglected. This study aimed to establish a more effective nomogram based on the log odds of negative lymph nodes/T stage ratio (LONT) to predict survival in surgically treated GC patients. METHODS: The data of resected GC patients were extracted from the Surveillance, Epidemiology, and End Results Program (SEER) database. Univariate and multivariate Cox regression analyses were used to identify the significant prognostic factors. The prognostic performance was assessed using a calibration plot, concordance index (C-index), and area under the (time-dependent receiver operating characteristic) curve (AUC) to compare the predicted survival probability based on the nomogram score groups. RESULTS: The results showed LONT as an independent prognostic factor for cancer-specific survival (CSS) and overall survival (OS), independent of clinicopathological factors. After removing potential redundancy, only LONT, T stage, N stage, location and age were used in the final nomogram model. The model had a higher C-index (0.736 ± 0.012) and AUC (0.798) than the TNM staging system (0.685 ± 0.012 and 0.744). The nomogram score could predict a significant survival difference between any two adjacent groups in terms of CSS and OS. CONCLUSION: High LONT is associated with improved survival of gastric cancer patients, independent of other clinicopathological factors. The prognostic nomogram model based on LONT could effectively predict CSS and OS for resectable GC patients. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00432-021-03654-y.