Fecal DNA test promising for colorectal cancer detection
Last Updated: December 23, 2004



NEW YORK (Reuters Health) - A non-invasive test that analyzes mutated
DNA in feces may be a useful method of detecting colorectal cancer in
average risk, asymptomatic individuals, according to a study in the
December 23rd issue of The New England Journal of Medicine.


In the study, 4404 average-risk adults age 50 or older underwent
fecal occult-blood testing with the Hemoccult II, fecal DNA testing,
as well as colonoscopy -- the reference standard.

Dr. Thomas F. Imperiale from the Indiana University School of
Medicine and the Regenstrief Institute in Indianapolis and
multicenter colleagues compared test results in a random subgroup of
2507 subjects seen in private-practice or university-based settings.

The fecal DNA test detected just over half (16 of 31) of all invasive
colorectal cancers (TNM stage I, II, or III), for a sensitivity of
51.6%, they report.

"The fecal DNA test was better than the Hemoccult II, the current
standard noninvasive screening test," Dr. Imperiale told Reuters
Health, noting that the Hemoccult II detected only 4 of 31 invasive
colorectal cancers in the same population, for a sensitivity of 12.9%.

Moreover, the sensitivity of the fecal DNA test was "more than twice"
that of Hemoccult II for detecting adenomas containing high-grade
dysplasia (32.5% vs 15.0%). Among 418 individuals with advanced
neoplasia, the DNA fecal test had a sensitivity of 18.2% compared
with a sensitivity of 10.8% for Hemoccult II.

"Specificity in subjects with negative findings on colonoscopy was
94.4% for the fecal DNA panel and 95.2% for Hemoccult II," the
authors also report.

Dr. Imperiale and colleagues point out that while "the majority of
neoplastic lesions identified by colonoscopy were not detected by
either noninvasive test, the multitarget analysis of fecal DNA
detected a greater proportion of important colorectal neoplasia than
did the Hemoccult II without compromising specificity."

They emphasize, however, that the place of DNA fecal testing in
colorectal cancer screening remains to be determined.

Dr. Steven H. Woolf, from the Virginia Commonwealth University in
Richmond, agrees, noting in an editorial that while testing stool for
DNA is a "potentially smarter strategy" than testing it for occult
blood, numerous questions remain including issues of
generalizability, superiority, testing intervals, not to mention
affordability.

The price tag for fecal DNA testing is $400 to $800 compared with a
cost of $3.00 to $40 for fecal occult blood testing, he notes.

The current study was funded by grants from EXACT Sciences, Inc.,
manufacturer of the stool DNA panel.





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