Abstract Background: Fecal SDC2 methylation is a promising noninvasive biomarker for colorectal cancer (CRC), whereas serum tumor markers, including carcinoembryonic antigen (CEA), carbohydrate antigen 19-9 (CA19-9), CA242, and CA50, are primarily used for postoperative surveillance and have limited value as standalone early diagnostic markers. This study evaluated the diagnostic performance of combining fecal SDC2 methylation with these four serum markers for CRC detection.
