The Screening Value of Septin9, SDC2, and BCAT1 Triple Gene Methylation Detection Combined with Colonoscopy for Early Colorectal Cancer

Objective : To explore the screening value of combined detection of Septin9, syndecan-2 (SDC2), and BCAT1 gene methylation biomarkers with colonoscopy for early colorectal cancer. Methods : From May 2025 to July 2025, community residents in Lucheng District, Changzhi City, Shanxi Province were enrolled as research subjects. The high-risk population was identified using the Asia-Pacific Colorectal Screening (APCS) score. For these high-risk individuals, blood samples were collected for Septin9, SDC2, and BCAT1 methylation detection, and colonoscopy was performed to analyze the screening value of the combined approach. Results : A total of 1,267 individuals completed the screening questionnaire, and 302 of them were identified as high-risk individuals. Of these, 200 underwent further detection and were included in the analysis. Based on colonoscopy findings and pathological diagnosis, participants were classified into four groups: normal/inflammation/other group (78 cases, 39.0%), polyp group (58 cases, 29.0%), precancerous lesion group (34 cases, 17.0%), and early colorectal cancer group (30 cases, 15.0%). The positive rate of the combined three-gene methylation detection was highest in the early colorectal cancer group, reaching 46.7%, which was significantly higher than that in other groups (P<0.001). Multivariate regression analysis showed that the positive result of the combined three-gene methylation detection was an independent risk factor for early colorectal cancer (adjusted OR=22.22, 95%CI: 7.38-66.92, P<0.001). ROC analysis revealed an AUC of 0.781, with a sensitivity of 70.0% and a specificity of 74.1%. Conclusion : The combined detection of the methylation of Septin9, SDC2, and BCAT1 genes has a favorable diagnostic efficacy in early screening of colorectal cancer, and is expected to serve as an important supplementary method for colorectal cancer screening.