New Blood Test for Colon Cancer Highly Accurate in Trial

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March 14, 2024 – Detecting colorectal cancer may be as easy as a simple blood test one day. 

Promising results of this new option -- the results of the study were published this week in the New England Journal of Medicine -- could help convert the estimated 1 in 3 people who don’t stay up-to-date on screenings that should begin at age 45. If everyone in the U.S. got screened regularly, as many as 90% of deaths linked to colorectal cancer may be avoided, the researchers wrote. Current screening options are often considered unpleasant experiences -- collecting a fecal sample at home and mailing it, or taking laxatives and going under sedation for a colonoscopy procedure.

The blood test can detect DNA shed into the bloodstream from tumors, and in a trial of more than 7,800 people, the new test accurately detected colon cancer at early, treatable stages 87% of the time. The false-positive rate was 10%. The test was less successful at detecting advanced precancerous lesions, with just 13% being detected. In comparison, fecal tests are about 42% successful at early detection, and colonoscopies are up to 93% accurate, according to a summary from the American College of Surgeons.

Colorectal cancer is the second leading cause of cancer death in the U.S. and one of the most common types of cancer overall. More than 150,000 people nationwide are diagnosed annually, and more than 50,000 people die each year from cancers of the colon or rectum.

Early detection at the precancerous stage is an important consideration, according to a group of medical professionals who specialize in diseases of the gastrointestinal tract. 

“While a blood test can be an additional tool, it shouldn't be used in place of a colonoscopy,” a statement from the American Gastroenterological Association advised.

“Colonoscopies allow detection and removal of precancerous polyps as well as identifying cancer early when it is in the most treatable stages. The blood test reported in the New England Journal of Medicine study is only designed to pick up cancers and not precancerous polyps.”

Current screening guidelines suggest a colonoscopy every 10 years for people at average risk, or annual fecal testing.

The new blood test would be given every 3 years, and, according to maker Guardant Health, may be considered for approval by the FDA sometime this year, NBC News reported.