New stool DNA test for neoplasia showed promising results

A comparison of stool DNA testing methods with occult blood tests for detecting colorectal cancer produced mixed results, according to findings published recently in the Annals of Internal Medicine.

Researchers from several U.S. institutions conducted the study of 4,482 average-risk adult participants.

The researchers assessed two stool DNA tests. Stool DNA test 1 was a pre-commercial 23-marker assay. Stool DNA test 2 was a novel assay that targets three broadly informative markers. These two tests were compared with the Hemoccult and Hemoccult Sensa (Beckman Coulter) fecal blood cards.

The researchers evaluated for efficacy in detecting screen-relevant neoplasia, including curable-stage cancer, high-grade dysplasia or adenomas larger than 1 cm.

Results showed that stool DNA test 1 provided no improvement over Hemoccult Sensa. Stool DNA test 2 detected significantly more neoplasms than either of the Hemoccult tests, but with more positive results in patients who had normal colonoscopies. Stool DNA test 2 also was highly sensitive in detecting adenomas.

Stool DNA test 2 detected 46% of screen-relevant neoplasms compared with 16% for Hemoccult and 24% for Hemoccult Sensa. For adenomas larger than 1 cm, Stool DNA test 2 detected 46%, Hemoccult detected 10% and Hemoccult Sensa detected 5%.

Daniel Chung, MD, of the Gastrointestinal Unit and Cancer Center at Massachusetts General Hospital, commented on these results in an accompanying editorial. “Bleeding is minimal and intermittent from adenomas, so the constant sloughing of adenomatous epithelial cells makes stool DNA testing a more attractive strategy,” he wrote.

“Stool DNA testing is currently imperfect, but reasons for optimism remain,” he wrote. “In time, perhaps a few strands of DNA may be all it takes to deliver an ounce of prevention.”

Ann Intern Med.2008;149:441-450.