Prediction of histopathology in colon cancer by multidetector computed tomography stratified by tumour side and microsatellite status: A national register study

OBJECTIVE: Multidetector computed tomography (MDCT) is widely used for colon cancer staging, although it has known limitations. This study evaluates the accuracy of MDCT in predicting the T category, regional lymph node metastases, and locally advanced disease. We stratified these predictions by tumour location, right-sided versus left-sided colon cancers, and, within right-sided colon cancers, further analysed them based by microsatellite instability status.

METHODS: A retrospective, population-based register study, utilising prospectively recorded data from the Danish Colorectal Cancer Group, on 14,455 patients undergoing resection for primary colon adenocarcinoma between 2015 and 2022. The sample size was determined by cases available in the DCCG database.

RESULTS: To predict pT3-T4 tumours, MDCT showed NPVs of 0.43 (right-sided) and 0.45 (left-sided), with 57% and 55% understaged, respectively; PPVs were a similar 91%. For MSI and MSS tumours, NPVs were 0.47 and 0.40, respectively. For lymph node metastases (pN1-2), PPVs were 0.47 (right-sided) and 0.50 (left-sided). NPVs for MSI and MSS right-sided cancers were 0.56 and 0.72, respectively. Sensitivity for locally advanced disease was 0.56 for both sides. PPVs were 0.62 (right-sided) and 0.67 (left-sided), resulting in 38% and 33% overstaged, respectively. For MSI and MSS tumours, PPVs were 0.60 and 0.65, with 40% and 35% overstaged, respectively.

CONCLUSIONS: Multidetector computed tomography for clinical staging in colon cancer regarding T category, regional lymph node metastases, and locally advanced disease has critical limitations. Clinicians must be aware that treatment decisions based on MDCT carry a risk clinically significant over- or undertreatment.

TRIAL REGISTRATION: Danish Colorectal Cancer Database (#DCCG_2023_02_24).