Nationwide practice in CT-based preoperative staging of colon cancer and concordance with definitive pathology

In an era of exploring patient-tailored treatment options for colon cancer, preoperative staging is increasingly important. This study aimed to evaluate completeness and reliability of CT-based preoperative locoregional colon cancer staging in Dutch hospitals.Patients who underwent elective oncological resection of colon cancer without neoadjuvant treatment in 77 Dutch hospitals were evaluated between 2011 and 2021. Completeness of T-stage was calculated for individual hospitals and stratified based on a 60% cut-off. Concordance between routine CT-based preoperative locoregional staging (cTN) and definitive pathological staging (pTN) was examined.A total of 59,558 patients were included with an average completeness of 43.4% and 53.4% for T and N-stage, respectively. Completeness of T-stage improved from 4.9% in 2011-2014 to 74.4% in 2019-2021. Median completeness for individual hospitals was 53.9% (IQR 27.3-80.5%) and were not significantly different between low and high-volume hospitals. Sensitivity and specificity for T3-4 tumours were relatively low: 75.1% and 76.0%, respectively. cT1-2 tumours were frequently understaged based on a low negative predictive value of 56.8%. Distinction of cT4 and cN2 disease had a high specificity (>95%), but a very low sensitivity (<50%). Positive predictive values of <60% indicated that cT4 and cN1-2 were often overstaged. Completeness and time period did not influence reliability of staging.Completeness of locoregional staging of colon cancer improved during recent years and varied between hospitals independently from case volume. Discriminating cT1-2 from cT3-4 tumours resulted in substantial understaging and overstaging, additionally cT4 and cN1-2 were overstaged in >40% of cases.