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

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. 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. 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. SFRP2 methylation in serum has the potential to be a non-invasive biomarker for colorectal cancer screening