Value of faecal exfoliated cells in colorectal tumour screening using SDC2 methylation test

Background This study aimed to evaluate the diagnostic value of a non-invasive methylation gene test in clinical colorectal tumour screening.Method The quantitative methylation-specific PCR technique was used to detect faecal methylated syndecan-2 (mSDC2) in patients who received the screening of colorectal cancer (CRC). To evaluate the positive predictive value (PPV) of mSDC2 in patients with colorectal cancer, advanced adenoma (AA), and colorectal tumor (CRN) in risk factor stratification.Method The quantitative methylation-specific PCR technique was used to detect faecal methylated syndecan-2 (mSDC2) in patients who received the screening of colorectal cancer (CRC). To evaluate the positive predictive value (PPV) of mSDC2 in patients with colorectal cancer, advanced adenoma (AA), and colorectal tumor (CRN) in risk factor stratification.Results The PPV of CRC, CRC + AA and CRN in male patients were 28.03%, 43.55% and 56.24%, respectively, which were higher than female patients. The positive detection rate of mSDC2 and the PPV of CRC gradually increased with age; The PPV in patients aged over 80 years was up to 78.05%, which was more significant than in younger patients with CRC. The PPV of CRC, AA and CRN were 37.10%, 11.80% and 63.37%, respectively. mSDC2 has a high detection rate of 85-100% in AA with intramucosal carcinoma alone or in combination with severe atypical hyperplasia or villous adenoma.Conclusion The mSDC2 test has a higher PPV in patients with colorectal cancer and colorectal adenoma (AD), especially in high-risk groups over 50 years of age, and may help in the early diagnosis of colorectal tumours in the future.