Blood Test May Detect Colon Cancer, Early Research Suggests

Blood Test May Detect Colon Cancer, Early Research Suggests

New research indicates many people may one day be able to avoid the uncomfortable procedure with a simple, noninvasive and reliable test for colon cancer.
NBC NEWS -- Most people would rather deliver a speech naked than get a colonoscopy (and some would argue there's not much difference). New research indicates many people may one day be able to avoid the uncomfortable procedure with a simple, noninvasive and reliable test for colon cancer.

According to a study published Friday in the Journal of Molecular Diagnostics, the future of colorectal cancer screening may lie in the development of biomarkers for the disease.

South Korean researchers from Genomictree Inc. and Yonsei University College of Medicine in Seoul discovered that alterations of a certain gene could discriminate pretty accurately between blood samples from people with cancer and blood samples from people without cancer. Experts say that the blood test findings, while "not quite ready for prime time," are promising.

"Based on the data they presented, it looks really good," said Chhavi Chauhan, the journal's scientific editor. "But to turn this into a diagnostic test available to everyone, the research has to be duplicated by others and with more numbers."

Researchers found that their simple blood test detected cancer correctly 87 percent of the time and was right about those without cancer about 95 percent of the time. When they looked only at early - or stage I - disease, the test caught the cancer 92 percent of the time.

While the promise of a blood test for colon cancer is still in early stages, this kind of research is "very exciting," said Dr. Eric Esrailian, co-chief of the division of digestive diseases at the David Geffen School of Medicine at the University of California, Los Angeles.

At the same time, other scientists are trying to determine whether an older, less invasive test is as good as a colonoscopy when it comes to a first screening.

Colonoscopies are credited with reducing deaths from colorectal cancer, but Dr. H. Gilbert Welch says there is no indication that the tests actually save more lives than a lower tech, less invasive alternative: the stool test.

Colonoscopy became much more popular than the alternative simply because "the basic idea of it was so appealing," said Welch, a professor of medicine at the Dartmouth Institute for Health Policy and Clinical Practice. "It was being used as the follow-up test for the [stool] test. And the idea was, 'Wow if we do this as a follow-up test, maybe we could just do it on everyone'."

Until now, though, no one's ever compared the two methods head-to-head in terms of the number of lives that could be saved.

That's what Dr. Douglas Robertson and his colleagues are doing in an ongoing trial: comparing the efficacy of using a stool test once a year with a follow-up colonoscopy for patients who test positive to simply getting a colonoscopy once every 10 years.

The idea behind the yearly stool test is to winnow down the pool of people who end up needing a colonoscopy. Testing positive on a stool test doesn't necessarily mean you have colon cancer, but it does mean you're at much greater risk.

The most important thing for people to know is that screening does save lives, said Robertson, an associate professor of medicine at the Dartmouth Medical School and chief of gastroenterology at the VA Medical Center in White River Junction, Vt.

Deaths among people who are screened are reduced by 30 to 50 percent.

The problem is getting people in the door.

Experts say one of the biggest failings of colorectal screening is that many people skip the tests. Part of the blame for that may be that physicians aren't telling patients there's an alternative to colonoscopy.

"There are data that show that if you give people options, they're more likely to comply with screening and that is what is most important - getting screened with some test," Robertson said.

Unfortunately, neither method is completely foolproof, said Esrailian of the University of California. Polyps can be missed in a colonoscopy because they are hidden in the crevices of the intestines. And not every cancer will be caught with a stool test.

Colorectal cancer is the second leading cause of cancer-related deaths among men and women in the U.S., according to the American Cancer Society. About 142,000 new cases of colorectal cancer will be diagnosed in the U.S. this year and over 50,000 people will die from it.

The good news is, colorectal cancer has declined 39 percent since 1975, said Welch.
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