<h4>Objective</h4>To explore the application value of fecal Syndecan-2 gene Methylation (mSDC2) detection, combined detection of serum Carcinoembryonic Antigen (CEA) and Carbohydrate Antigen 72-4 (CA72-4) in screening of Colorectal Cancer (CRC) and precancerous lesions.<h4>Methods</h4>A total of 196 participants were enrolled in this case-control study from March to December 2023, including 65 with CRC, 38 with advanced adenomas, 33 with non-advanced adenomas, and 60 controls. The gene discussed is SDC2; the disease is adenoma.