Researchers have developed the first reliable blood test for detecting colorectal adenomas and colorectal
cancers – findings that may prove useful for identifying patients who would benefit most from
colonoscopy. The test examines blood levels of the CD24 protein, which is produced early in the
multistep process of colorectal cancer development and may be involved in the spread of tumour cells.

“Screening is effective for early colorectal cancer detection and prevention, but for a range of reasons,
many people are reluctant to undergo colonoscopy. Most people, however, are willing to have a blood
test,” said lead author Sarah Kraus, PhD, who heads a research laboratory at Tel Aviv Souraski Medical
Center in Israel. “The CD24 blood test holds promise for identifying the patients at risk for colorectal
cancer and could help guide the best use of colonoscopy resources.”

Colonoscopy and stool testing for occult blood are currently the primary methods for detecting colorectal
cancer and colorectal adenomas (growths that have the potential to progress to cancer). However,
colonoscopy remains underutilized in the U.S., and the stool blood test is not very sensitive.

In this study, Dr. Kraus and her colleagues examined the sensitivity (ability to accurately detect an
abnormality) and specificity (ability to differentiate cancer or adenomas from other diseases) of the CD24
blood test in 150 patients undergoing colonoscopy. They found that the CD24 test was 92.3 percent
sensitive and specific for detecting colorectal cancer, and 84.2 percent sensitive and 89.2 percent specific
for detecting adenomas.

Dr. Kraus noted that larger studies are needed to validate these findings before the blood test can be
widely used for colorectal cancer screening. The test is expected to be relatively inexpensive (less than
$50).


Source: 2010 Gastrointestinal Cancers Symposium