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Could a genetic test on stool samples make colonoscopies unnecessary someday?

Let’s be honest: nobody really wants to get a colonoscopy, even if the procedure is crucial in finding nascent tumors.  So, here’s hoping researchers working on less uncomfortable alternatives succeed.

One possibility comes from a group at Maastricht University Medical Center in the Netherlands , which reports in the latest Journal of the National Cancer Institute (JCNI) on a potential biomarker for colorectal cancer from cells contained in stool samples.

Headed by Manon von Engeland, the research group compared stool samples taken from subjects who had colorectal cancer with those from subjects who did not and found a significant difference in a gene called NDRG4.  

In particular, the difference lies in a region of NDRG4 called the promoter, which acts as a switch to turn on the gene. In cells collected from cancer patients, the promoter was highly methylated--it had many more chemical compounds called methyl groups attached to it--compared with those from non-cancer subjects.  

Methylation inhibits the promoter from activating the NDRG4 gene, which based on additional findings published in the paper, likely has a role in suppressing tumors. This difference led the scientists to conclude that high levels of NDRG4 methylation may flag colon cancer.

In an accompanying editorial for JCNI, Gad Rennert of Carmel Medical Center in Haifa , Israel , calls the findings promising, saying that the NDRG4 marker is more sensitive and specific than previously tested genetic markers. Family history plays a strong role in colorectal cancer, with many genes implicated in raising the risk, but NDRG4's role has not been previously studied.

Rennert goes on to say that a collection of biomarkers including NDRG4 may be the best approach to improving the technique’s precision.   Other groups, such as the diagnostic company Exact Sciences, are working on similar stool tests, too, focusing on different biomarkers.

However, as the National Cancer Institute (NCI) points out, more testing needs to be done to determine if biomarkers can detect precancerous cells as effectively as colonoscopies.   Removal of precancerous polyps is one of the best ways to avoid becoming one of 49,000 people in the U.S. who die each year from colon cancer, according to the NCI.       

Image of the colonoscopy courtesy of leezsnow via IstockPhoto

 

 

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