To Explore the Effect of NLR and PLR on Prognosis of Rectal Cancer on the basis of T3 substage, and to draw the related nomogram

Background: Approximately 50% of patients with rectal cancer are classified into T3 stage, and they are positioned as substage by various criteria. These patients with different neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) develop disparate outcomes. We sought to develop and validate nomograms to predict survival in patients with rectal cancer on the basis of T3 substage. Methods: : We conducted a retrospective cohort study by collecting 170 cases from China. Individuals with rectal cancer after 2 or more years of follow up after surgery were eligible for inclusion. Candidate predictors consisted of NLR, PLR, T3 substage and clinical characteristics available at the time of rectal cancer diagnosis. The optimal cut-off values for NLR and PLR were determined using X-Tile (Version 3.6.1) software and were determined before statistical analyses. Variables with P values below 0.1 in the univariable analyses were further evaluated using Cox multivariate analysis. Model discrimination was assessed using receiver operating characteristic (ROC) curve and concordance index (C-index) analysis. Results were internally validated using related software. Results: : We analyzed data from 170 patients with T3 rectal cancer. The optimal cut-off value of NLR in relation to overall and disease-free survival were 3.1 and 2.9, and that of PLR were 181.9 and 202.7. Among them, postoperative adjuvant chemotherapy, T3 substage, N stage, CA199 and NLR were independent risk factors affecting overall survival（OS）and disease-free survival (DFS). There was no significant difference in survival rate between T3a and T3b, or between T3c and T3d. The final nomograms of 2-year OS (area under the curve,0.886; The c-index,0.870) and 2-year DFS (area under the curve,0.895; The c-index,0.867) were developed according to independent risk factors analyzed by SPSS 26 (SPSS Inc., Chicago, IL, USA) software. The calibration curves showed negligible optimism. Conclusion: We developed nomograms based on postoperative adjuvant chemotherapy, T3 substage, N stage, CA199 and NLR to help identify patients with poor prognosis and to guide individualized therapy.