[Fecal Biomarker for Colorectal Cancer Diagnosis]

The fecal occult blood test (FOBT) is widely used for colorectal cancer (CRC) screening to reduce the mortality rate associated with this cancer. However, several problems exist, as FOBT results can contain some false-negative CRC patients and some-false positive healthy subjects. Thus, to resolve these problems, several fecal biomarkers based on fecal protein, fecal DNA, and fecal RNA have been reported. Fecal calprotectin, which indicates intestinal bleeding or inflammation of the colon mucosa, and fecal tumor M2-PK, which is produced by cancer cells, have been extensively investigated as fecal protein biomarkers. To detect small amounts of CRC-specific proteins, the chemiluminescent enzyme immunoassay (CLEIA), which is a highly sensitive protein detection method using immunomagnetic beads, will be used. DNA mutation of APC, KRAS, and TP53 genes and DNA methylation of VIM, TFPI2, BMP3, NDRG4, and SFRP2 genes were reported as fecal DNA biomarkers. Consequently, a fecal DNA test named Cologuard from Exact Sciences was approved by the FDA in August 2014. Fecal COX2, MMP7, miR-106a, miR-92a, and miR-223 were also reported as fecal RNA biomarkers. This review article summarizes fecal biomarkers using fecal samples for CRC diagnosis.