Jan 20, 2010 -- A new blood test has potential for detecting -- and even
preventing -- colon cancer, a study shows.
The test spots a protein called CD24 that is elevated in the presence of
both colon cancer and growths that
are destined to become colon cancer. In contrast, levels of the protein are low
in healthy tissue.
CD24 is produced early in colorectal cancer development and may be involved
in the spread of tumor cells, says researcher Sarah Kraus, PhD, of the Tel Aviv
Souraski Medical Center in Israel.
"Colon cancer is often diagnosed at a late stage, when it has a poor
prognosis. The idea of the new test is to detect the cancer earlier when it is
more curable," she tells WebMD.
The test may also prove useful for identifying patients who would benefit
most from colonoscopy, Kraus says.
The findings were released today in advance of the annual Gastrointestinal
Cancers Symposium, being held later this week in Orlando, Fla.
Colorectal cancer is one of the most common forms of cancer, diagnosed in
more than 150,000 people each year in the U.S. Although colonoscopy can detect
the disease at an early stage when it is most curable -- and even prevent it by
finding polyps before they become cancerous -- many people shun the procedure
because of discomfort, pain, and a small risk of
There are other noninvasive tests for colorectal cancer, such as the fecal
occult blood test, which looks for blood in the stool. But occult, or hidden,
blood is also found in the stool of people with a host of other conditions,
such as hemorrhoids, resulting in a high rate of false-positive results.
CD24 not only predicts the presence of the cancer with a low false-positive
and false-negative rate, but also can detect high-risk precancerous growths,
Removing them can prevent colon cancer from developing, she explains.
In the new study, Kraus and colleagues first measured levels of the CD24
protein in 63 people with colon cancer, 19 people with adenomas, or
precancerous colon growths, and 68 healthy people.
"CD24 was [dramatically] elevated in colon cancer and adenoma patients,
compared with healthy subjects," Kraus says.
Then, they further tested the accuracy of the CD24 blood test in 73 people:
11 had colon cancer, 24 had adenomas, and 38 showed no signs of colon
The researchers found that the test accurately detected colorectal cancer in
92% of cases; only 8% of colon cancers were missed. It gave false-positive
results to 8% of people who didn't have the cancer.
As for adenomas, the test accurately caught 84% of growths. The
false-positive rate was 11%.
The next step is to validate the findings in studies of larger groups of
people, Kraus says.