BackgroundLaparoscopic anterior resection with trans-rectal specimen extraction (NOSES) has been demonstrated as a safe and effective technique in selected patients with upper rectal cancer (RC). However, improper selection of RC candidates for NOSES may lead to complications such as bacteria contamination and anastomotic leak. Unfortunately, no tools are available for evaluating the risk and excluding improper cases before surgery. This study aims to investigate independent clinical-pathological predictors for selection of candidates for NOSES surgery in upper RC and to develop a validated scoring nomogram to facilitate clinical decision making.MethodsThe study was performed at Shanghai East hospital, a tertiary medical center and teaching hospital. A consecutive and eligible serial of 111 patients with upper RC underwent elective laparoscopic anterior resection with or without NOSES between February and October of 2017. Multivariate analyses were performed to compare characteristics between the two surgical techniques. Odds ratios (OR) were determined by logistic regression analyses to identify and quantify the ability of predictors for selection of NOSES. The nomogram was constructed and characterized by c-index, calibration, bootstrapping validation, ROC curve analysis, and decision curve analysis.ResultsUpper RC patients with successful NOSES tended to be featured with female gender, negative preoperative CEA/CA19-9, decreased mesorectum length (MRL),ratio of diameter (ROD) and ratio of area (ROA) values, while no significant correlations were observed with age, body mass index (BMI), tumor location, and tumor-related biological characteristics (ie., vascular invasion, lymph node count, TNM stages). The nomogram incorporating three independent preoperative predictors including gender, CEA status and ROD achieved a high c-index of 0.814 and considerable reliability, accuracy and clinical net benefit.ConclusionsNOSES for patients with upper RC is multifactorial. The first nomogram is useful for proper patient selection in the future.