Testing for DNA changes in stools might provide a new, accurate, and less invasive way to screen patients for colorectal cancer, according to an article in the April 17th issue of the Lancet.

In the current study, Hannes M Muller and his Austrian colleagues investigated whether patients with colorectal cancer could be identified by testing stool samples for changes in DNA methylation, a form of genetic alteration that is common in colorectal cancer cells. The researchers used a polymerase chain reaction assay to identify DNA changes in stools from patients with the disease and from healthy controls in order to assess the most promising DNA methylation markers from a long list of candidate genes. They then tested for these potential markers in samples from two sets of patients and healthy controls for a total of 49 individuals.

A gene known as SFRP2 was methylated more frequently in DNA from the stools of patients with colorectal cancer than in samples from people without the disease, with a sensitivity of 77 to 90 percent and specificity of 77 percent. SFRP2 methylation could, therefore, be useful as a marker in screening for colorectal cancer.

Martin Widschwendter, the principle investigator, said, "To our knowledge, SFRP2 methylation represents one of the most sensitive markers for identifying colorectal cancer, besides mutation analysis and protein analysis, in stool samples. Whether a panel of genetic and epigenetic markers in stool could be used to identify colorectal cancer at an early stage remains to be shown."