Although the research is still in its infancy, "we are trying to develop a test that can be integrated into an annual checkup that is just another box for a doctor to check on the menu of blood tests he or she can order," says study author Søren Jensby Nielsen, PhD, the scientific manager for Diagnostic Product Development at Exiqon A/S in Copenhagen, Denmark. Exiqon is developing the new screening test and technology.
Researchers used cutting-edge technology to analyze blood samples taken from people with early stage colon cancer and people without colon cancer. They identified a specific biomarker profile in the blood samples that could help identify people with colon cancer earlier and less invasively than with colonoscopy. The study focuses on short RNA molecules or microRNAs, which are found in the blood in small but detectable amounts.
"We have the potential to detect the majority of early colon cancers with this test, but we are just one year into a four-year project," he tells WebMD. "We are not saying that we can diagnose colon cancer with 100% specificity from a blood sample, but our test would be an alarm signal and if you are positive, you should have a colonoscopy," he says.
When and how frequently this blood test could be administered is still unknown. "More research is needed to validate these findings," he says. Nielson says the screening test must be validated before he can share any numbers about how specific or sensitive the new blood test is.
Regular colon cancer screening typically begins at age 50, or earlier if there are any symptoms or risk factors. The U.S. Preventive Services Task Force recommends screening for colorectal cancer using colonoscopy or other colon cancer screening tests. During a colonoscopy, a doctor guides a thin, flexible tube capped with a tiny camera through the colon to look for tumors or other abnormalities.
Blood Test for Early Colon Cancer Is Holy Grail
"Early detection of colon cancer has been shown to reduce mortality, but compliance with screening colonoscopy is a big issue, so a blood test that is simple to perform, if it was sensitive and specific, would, of course, be the holy grail," says Robert S. Bresalier, MD, a professor of medicine at the University of Texas M.D. Anderson Cancer Center in Houston.
"There is a lot of interest in blood, stool, and other less invasive screening tests to replace colonoscopy," he says.
Whether or not this specific test is the holy grail is unknown, he says. "This is encouraging and exciting, and uses cutting-edge technology, but it needs to be validated," he says. "We will have to wait and see how this performs."
Leonard Augenlicht, PhD, a professor of medicine and cell biology at the Albert Einstein College of Medicine in the Bronx, says that the only definitive early screening test for colon cancer is the colonoscopy. "It is not as bad as it sounds, but many people are reluctant, so we looking for better noninvasive tests," he tells WebMD.
"This could be a noninvasive test that is relatively simple to perform, but the big question is just how efficient or valid is this test," he says.
"The danger is the risk of a false-negative result," he says. "If someone is told that they are negative on the basis of this test or another blood test, and that discourages them from more definitive testing, cancer could be missed."