New Colon Cancer Test Might Spot Trouble Earlier

By Amanda Gardner
HealthDay Reporter
Thursday, January 24, 2008; 10:00 AM

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THURSDAY, Jan. 24 (HealthDay News) -- Researchers say they have zeroed in on a biomarker that could detect colorectal cancer in its earliest stages in a simpler, less invasive and more accurate way than existing blood tests.

The marker, called colon cancer-specific antigen-2 (CCSA-2), could also differentiate between early- and late-stage disease, the researchers added.

The study was one of several concerning colon cancer being presented at the annual Gastrointestinal Cancers Symposium being held Jan. 25 to 27 in Orlando, Fla.

A second study found that patients who are uninsured or who have coverage with Medicaid tend to be diagnosed with colorectal cancer at a later stage than individuals with private insurance or Medicare. This is the first nationwide survey to confirm similar findings from smaller polls.

And a third study is a step on the road to so-called personalized medicine. "This study assesses the benefit of treatment with a monoclonal antibody for colorectal cancer patients based on their tumor's molecular signature," Dr. Nicholas Petrelli, an official with the symposium, said during a Wednesday teleconference on the findings.

According to the American Cancer Society, colorectal cancer is the third most common cancer among American men and women. Some 150,000 new cases are diagnosed each year in the United States.

Regular screening can catch the disease while it is still curable. Colon cancer can also be prevented if polyps and adenomas are found and removed before they become malignant.

There are already blood tests for colorectal cancer, but they result in false-positives in 60 percent to 90 percent of cases, depending on the test, said the authors of the first study.

The researchers, from Johns Hopkins University and the University of Pittsburgh, looked at 135 blood samples from individuals who had undergone colonoscopies. They were compared with samples from individuals with other types of cancer or with benign diseases.

Only about 20 percent of results were false positives, while only 9 percent of cancers went undetected.