ObjectivesThis study investigated the prognostic role of log odds of negative lymph node/T stage (LONT) and established a nomogram based on LONT to predict the prognosis in colorectal cancer (CRC) patients.DesignA retrospective cohort study.Setting and participantsWe enrolled 80 518 CRC patients from the Surveillance, Epidemiology and End Results database between 2010 and 2015. The dataset was split into a training cohort (56 364 patients) and a validation cohort (24 154 patients) at a ratio of 7:3. Furthermore, 500 CRC patients who underwent surgery in the Tenth Affiliated Hospital of Southern Medical University between 1 January 2017 and 20 December 2018, were recruited as the external validation set.Outcome measures1-, 3- and 5-year cancer-specific survival (CSS).MethodsThe univariate and multivariate Cox regression analyses were carried out to identify the significant independent prognostic factors of CSS. A nomogram was established based on LONT to predict the prognosis. The performance of the nomogram was comprehensively assessed via the time-dependent receiver operating characteristic curve, concordance index (C-index), calibration curve and decision curve analysis (DCA) comprehensively. Moreover, Kaplan-Meier curves were performed to assess the CSS of the three risk subgroups.ResultLONT was a significant independent prognostic factor for CSS (LONT1 vs LONT2, HR=0.670, 95% CI 0.642 to 0.698, p<0.001; LONT1 vs LONT3, HR=0.443, 95% CI 0.420 to 0.467, p<0.001). LONT, age, sex, race, subsite, differentiation, histology, tumour size, T stage, N stage, M stage and chemotherapy were included in the nomogram. The 1-, 3- and 5-year survival area under the curve were 0.856, 0.862 and 0.852, respectively. The C-index of the model was 0.809 (95% CI 0.825 to 0.839) in the model. The calibration curve and DCA verified the favourable predictive performance and clinical application of the nomogram.ConclusionCRC patients with a high LONT had a low incidence of CSS. The nomogram based on LONT could effectively predict the CSS of CRC.
