Performance of a MethyLight assay for methylated SFRP2 DNA detection in colorectal cancer tissue and serum

Background: Colorectal cancer is one of the five most common cancers in China, and its incidence is steadily increasing. An accurate and non-invasive screening method is needed to increase the population uptake of colorectal cancer screening. Secreted frizzled-related protein 2 (SFRP2) has been found to be hypermethylated in most colorectal cancer patients, and it may fulfill the role of a non-invasive biomarker for colorectal cancer screening. Methods: Methylation status of SFRP2 was examined in 17 cancer tissues and paired adjacent paracancer tissues by a new SFRP2 MethyLight assay, which was also used to test the serum of 62 patients with colorectal cancer and 55 normal individuals. Results: The limit of detection of the SFRP2 MethyLight assay was about 200 pg per reaction. The SFRP2 methylation level was higher in 94.1% colorectal cancer tissues than in paired adjacent paracancer tissues (P<0.001). The sensitivity and specificity of SFRP2 for detecting colorectal cancer in serum were 69.4% (95% confidence interval (CI) 56.2, 80.1%) and 87.3% (95% CI 74.9, 94.3%), respectively. Conclusion: SFRP2 methylation in serum has the potential to be a non-invasive biomarker for colorectal cancer screening.