External Quality Assessment of SDC2 Promoter Hypermethylation Detection in Colorectal Cancer by Novel EQA Materials for Reliable Clinical Testing in China

Background Colorectal cancer (CRC) is a significant public health concern, and the early screening and diagnosis of this disease have a substantial impact on patient outcomes. Syndecan 2(SDC2) promoter hypermethylation has emerged as a crucial marker for the early detection of CRC. However, the clinical detection of SDC2 methylation in China lacks appropriate SDC2 external quality assessment (EQA) materials and nationwide EQA to monitor the accuracy of the assay, which is essential for ensuring reliable and consistent results. Results A total of 3 monoclonal cell lines with hypermethylation of SDC2 promoter were constructed, and they were used as a novel EQA material to successfully conduct a nationwide EQA of SDC2 methylation detection. In this EQA report, there are 8 false results (3 commercial diagnostic laboratories had one false positive result each and 2 commercial diagnostic laboratories had one false negative each, while 1 commercial diagnostic lab had three false negative results). Of the 140 participating laboratories, 134 (95.71%) obtained acceptable performance scores and 6 (4.29%) required improvement. Conclusions The novel EQA materials helps monitor the accuracy of the assay of the clinical detection of SDC2 promoter hypermethylation in CRC in China, ensuring reliable and consistent results. Improving the reproducibility and accuracy of SDC2 methylation detection contributes to early screening and diagnosis of CRC.