Stool test shows promise in detecting many cancers
CHICAGO, 03 june 2009– Using just a stool sample, doctors may now be able to detect colon and many other cancers of the digestive tract including stomach, pancreatic, bile duct and esophageal cancer, U.S. researchers said on Tuesday.
They said a new test, which detects genetic material shed from the surface of cancer cells, found nearly 70 percent of assorted digestive tract cancers.
And the DNA test accurately showed negative results in all 70 healthy patients they tested, Dr. David Ahlquist of the Mayo Clinic in Minnesota told the Digestive Disease Week meeting in Chicago.
"It opens the door to detecting cancers that are, sadly, not screened. The mortality rates of these cancers is extremely high," Ahlquist said in a telephone interview.
"In pancreatic cancer, the five-year survival rate is only about 5 percent or less. Without detection at an early stage, it will be hard to make much progress."
Gastrointestinal cancers account for about one in four cancer deaths in the United States, but currently, patients are only routinely screened for colon cancer.
The stool sample test is an expanded version of a DNA test Ahlquist and colleagues are working on for colon cancer. It looks for evidence of cells from tumors and precancerous polyps as they pass through the gastrointestinal tract.
"What's common to all of the cancers in the GI tract is that they shed cells and they are going downstream and are excreted in the stool. We've exploited that common biology to explore this as a screening approach," Ahlquist said.
The team tested 70 patients with various cancers of the digestive tract, including colon, throat, esophagus, stomach, pancreatic, bile duct, gallbladder and small bowel to see if gene mutations could be found in stool samples. They also used the test on 70 healthy patients.
It found 65 percent of esophageal cancers, 62 percent of pancreatic cancers and 75 percent of bile duct and gallbladder cancers.
And it found 100 percent of both stomach and colorectal cancers. The test worked equally well on early and late-stage cancers. "We've looked at DNA changes that are cancer-specific. They have proved to be a very reliable marker in this study," he said.
Ahlquist said both he and Mayo Clinic have a financial interest in the DNA stool test, which they hope to license to a company that will commercialize it.