Performance of risk-based scoring systems in Colorectal cancer screening

Abstract

Background: According to the 2024 national health statistics of Mongolia, colorectal cancer accounts for 5.1% of all newly diagnosed cancers, with 74.1% detected at an advanced stage. Although population-based screening programs have recently been implemented, no studies have established a risk factor–based scoring system with an optimal cut-off value or evaluated its clinical utility in resource-limited settings in Mongolia. Aim: To develop a modified APCS (mAPCS) scoring system and evaluate its clinical applicability for colorectal cancer screening. Materials and Methods: A hospital-based prospective cross-sectional study was conducted between December 2024 and February 2026 at the outpatient clinics of the Mongolian National University of Medical Sciences and the Mongolia–Japan Hospital. A total of 447 eligible participants were enrolled. Anthropometric measurements (height and weight) were obtained, and six categories of questionnaires (demographic data, APCS risk score, behavioral factors, medical history, and medication use) were administered. Eleven participants declined colonoscopy; therefore, 436 participants underwent colonoscopic examination, with histopathological evaluation performed when indicated. Results: A total of 436 participants were included, of whom 282 (64.7%) were female, with a mean age of 54.8±11.5 years. Colorectal adenomas (advanced and non-advanced) and colorectal cancer were detected in 199 (45.6%) participants. Among them, 43 (21.6%) had advanced colorectal neoplasia. Multivariable regression analysis identified age ≥55 years (OR 4.8), BMI ≥28 kg/m² (OR 3.6), and a family history of colorectal cancer (OR 3.1) as independent risk factors for advanced neoplasia. The optimal cut-off value for the mAPCS score was 4, with an overall diagnostic accuracy of 41.7% (sensitivity 97.7%, specificity 35.6%). Conclusions: 1. Age ≥55 years, BMI ≥28 kg/m², and a family history of colorectal cancer were identified as independent risk factors for advanced colorectal neoplasia. At a cut-off value of ≥4, the mAPCS scoring system demonstrated high sensitivity (97.7%), low specificity (35.6%), high negative predictive value (99.2%), and low positive predictive value (14.2%). 2. Therefore, the mAPCS scoring system may serve as a useful tool for risk stratification and efÏcient allocation of limited resources in colorectal cancer screening.