A nomogram for predicting feasibility of laparoscopic anterior resection with trans-rectal specimen extraction (NOSES) in patients with upper rectal cancer

BACKGROUND: Laparoscopic anterior resection with trans-rectal specimen extraction (NOSES) has been demonstrated as a safe and effective technique in appropriate patients with upper rectal cancer (RC). However, improper selection of RC candidates for NOSES may lead to potential surgical and oncological unsafety as well as 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 estimate its clinical relevancy and to investigate independent clinical-pathological predictors for identifying candidates for NOSES in patients with upper RC and to develop a validated scoring nomogram to facilitate clinical decision making. METHODS: The study was performed at Shanghai East hospital, a tertiary medical center and teaching hospital. 111 eligible patients with upper RC who underwent elective laparoscopic anterior resection between February and October of 2017 were included in the final analysis. Univariate and 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 clinical relevancy and ability of predictors for identifying NOSES candidate. The nomogram was constructed and characterized by c-index, calibration, bootstrapping validation, ROC curve analysis, and decision curve analysis. RESULTS: Upper 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 statistical correlations were observed with age, body mass index (BMI), tumor location, and tumor-related biological characteristics (ie., vascular invasion, lymph node count, TNM stages). Furthermore, the two techniques exhibited comparably low incidence of perioperative complications and achieved similar functional results under the standard procedures. The nomogram incorporating three independent preoperative predictors including gender, CEA status and ROD showed a high c-index of 0.814 and considerable reliability, accuracy and clinical net benefit. CONCLUSIONS: NOSES for patients with upper RC is multifactorial; while it is a safe and efficient technique if used properly. The nomogram is useful for patient evaluation in the future. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12893-021-01290-4.