BALTIMORE, Jan. 30 (UPI) -- A genetically based stool test for colon cancer can detect the earliest, curable stages of colon cancer, researchers report in the Jan. 31 issue of the New England Journal of Medicine.
"Colorectal cancer is of those cancers in which death is preventable if the cancer is detected early," Dr. Bert Vogelstein, professor of oncology at the Kimmel Cancer Center, Johns Hopkins University in Baltimore, told United Press International. "Though there are screening methods available, they are not being used as widely and, importantly, as routinely as they could be -- as evidenced by the fact that about 60,000 people die of colorectal cancer in the United States every year, and about half a million die worldwide."
Colon cancer is 90 percent curable if detected and treated before spreading to other organs.
The researchers studied stool samples taken from 74 subjects, including 28 with early colon cancers, 18 with premalignant colon tumors called adenomas and 28 with no disease. The test revealed a genetic mutation in 61 percent of those with early colon cancer, in 50 percent with premalignant adenomas and in none who were disease-free.
"In terms of its applicability based on the results of this research, it's very encouraging," Vogelstein said. "There were no false positives with the method we used, which is very important for any potential screening test. And the sensitivity for early cancers is 61 percent.
"We feel that with a little more research, we'll get that up to 70 percent. That is comparable to other widely used screening tests, for example mammography and Pap smears, which are widely used, have become part of the annual check-up routine and save a lot of lives," he added.
The new test is believed to be the first to accurately uncover colon cancer linked to APC gene mutations in DNA shed into feces. APC gene mutations are present in nearly every cancer, but normal copies appear in stool as well as mutated gene copies.
The researchers created a new technology named Digital Protein Truncation or Dig-PT. It enabled them to divide extracted DNA into tiny portions, permitting the mutated copies of the gene to stand out.
"Essentially, Dig-PT makes it possible to find the needle by dividing the haystack into very small, more manageable piles," said Giovanni Traverso, graduate student at Johns Hopkins and lead author of the study.
"The primary obstacle in colon cancer screening at the moment is getting the general public to believe that screening is a) effective and b) not too onerous. This test appears to satisfy both criteria," Dr. Lindsay Frazier, assistant professor of pediatrics at Harvard University Medical School in Boston told UPI. "It remains to be seen whether the cost of the test will make it a competitive option compared to the other available screening tests. It is likely that with the advances in automation of genetic analyses that are so rapidly occurring that it will be a cost-effective option."
The research was funded by the National Colorectal Cancer Research Alliance, the Caroline Law Fund, University of Texas MD Anderson Cancer Center, the Clayton Fund, and the National Institutes of Health.
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(Reported by Bruce Sylvester from West Palm Beach, Fla.)
