SDC2 and colorectal cancer: Of these, 115 were excluded due to repetitive publications, and 70 articles were excluded based on the inclusion/exclusion criteria: 38 were not relevant to the diagnostic accuracy of SDC2 methylation in colorectal cancer; 10 were review articles; 12 were conference abstracts; 1 was an editorial; 1 was non-English literature; 1 was book chapter; 1 use bowel lavage fluid as sample for detecting methylated SDC2; 6 were unable to be contained sufficient data to form 2 × 2 tables.