Fecal Blood Tests Effective at Spotting Colon Cancer

But they are underused, experts say.

By Ed Edelson
HealthDay Reporter
Tuesday, September 25, 2007; 12:00 AM

Copyright © 2007 ScoutNews, LLC. All rights reserved.

TUESDAY, Sept. 25 (HealthDay News) -- A new generation of fecal blood tests can screen for colon cancer with unprecedented accuracy, researchers report.

But the tests, although easily available, are greatly underused, said study author Dr. James Allison, an investigator with the Kaiser Permanente division of research in Oakland, Calif.

"A lot of gastroenterologists think that colonoscopy is the only test for colon cancer," Allison said.

But colonoscopy is also expensive, uncomfortable and carries the risk of damage such as internal bleeding, he said. A simple fecal occult blood test, costing less than $30 and done in minutes, can single out that small percentage of the general population that would benefit from colonoscopy, Allison said.

The study is published in the Sept. 25 issue of the Journal of the National Cancer Institute.

At least 10 fecal occult blood tests have been approved by the U.S. Food and Drug Administration, Allison said. The most widely used is Hemoccult, which has been shown in controlled trials to reduce mortality from colorectal cancer.

The two tests described in the new journal report use different methods to detect hidden blood. "Each one has different pluses and minuses," Allison said. "We need to find out which is best -- which we should be using in the United States and elsewhere."

One of the tests described in the journal report uses guaiac, the chemical in Hemoccult, as a detector. The other uses an immunochemical method. Screening of 5,841 people showed the immunochemical test to have a sensitivity of 81.8 percent, meaning that it detected that percentage of colorectal cancers and polyps. And it had a specificity -- the ability to determine which people did not have the conditions -- of 96.9 percent. The guaiac test was 64.3 percent sensitive and 90.1 percent specific.

Allison has been conducting something of a crusade to promote use of fecal occult blood tests to screen for colorectal cancer. "I am doing a tour of the United States and talking to primary-care physicians," he said.