Detection of colorectal cancer cells from feces using quantitative real‐time RT‐PCR for colorectal cancer diagnosis

Early detection of colorectal cancer (CRC) is desired for reducing its mortality rate. Recently, the feasibility of a new method for isolating colonocytes from feces was demonstrated, followed by direct sequencing analysis for detecting colorectal cancer. In the present study, gene expression analysis was conducted using quantitative real-time reverse transcriptase-polymerase chain reaction (RT-PCR). One hundred and sixty-six patients with CRC and 134 healthy volunteers were enrolled. Messenger RNA expressions of CEA, MMP7, MYBL2, PTGS2 and TP53 in the colonocytes isolated from feces were analyzed by quantitative real-time RT-PCR. Beta-2-microglobulin, used for internal control, could not be detected in approximately 25% each of the CRC patients (39/166) and healthy volunteers (33/134). CEA expression did not differ significantly between CRC patients and healthy volunteers (P = 0.21). MMP7, MYBL2, PTGS2 and TP53 gene expressions were significantly higher in CRC patients than in healthy volunteers (P < 0.001). The overall sensitivity and specificity using these gene expressions were 58.3% (74/127, 95% CI; 49.2-67.0) and 88.1% (89/101, 95% CI; 80.2-93.7), respectively. The sensitivity was dependent on the tumor location (P = 0.01) and tumor size (P = 0.02), but not the tumor depth (P = 0.06) or cancer stage (P = 0.37). Gene expression analysis of colonocytes isolated from feces may be a useful method for CRC screening, if the number of isolated colonocytes is sufficiently high for analysis by quantitative real-time PCR. Therefore, improvement of the colonocyte retrieval system from feces may be necessary for the technique to be developed for clinical use.