A fecal test that detects mutated DNA from tumors may offer better screening for colorectal cancer than the standard Hemoccult II test for blood in stool, according to researchers. Even so, most tumors identified by colonoscopy won't be detected by either the DNA or fecal occult blood test.

The study involved 4,404 adults age 50 or older at average risk for colorectal cancer. Researchers tested stool samples from all of the people using both DNA and Hemoccult II tests. All subjects also underwent colonoscopy. Researchers analyzed results from a randomly selected group of 2,507 people.

The fecal DNA test detected more cases of invasive colorectal cancer (16 of 31 cases) than the Hemoccult II test (4 of 31 cases). The DNA test was also about twice as sensitive as the Hemoccult test at detecting precancerous tumors. Both tests had about the same rate of false-positive results.

Despite promising results, DNA fecal testing for colorectal cancer may not replace Hemoccult testing any time soon: The DNA test costs between $400 and $800, compared with $3 to $40 for a Hemoccult test.

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