MONDAY, Aug. 11, 2014 (HealthDay News) -- The U.S. Food and Drug
Administration on Monday approved a new at-home, DNA-based stool
test that screens for colorectal cancer with more than 90 percent
The decision was based on an FDA panel's unanimous decision in
March that the benefits of Exact Sciences Corp.'s Cologuard test
outweighed its risks.
"This approval offers patients and physicians another option to screen for colorectal cancer," Alberto Gutierrez, director of the Office of In Vitro Diagnostics and Radiological Health at the FDA's Center for Devices and Radiological Health, said in an agency news release.
"Fecal blood testing is a well-established screening tool and the clinical data showed that the test detected more cancers than a commonly used fecal occult [blood] test," he said.
At the same time, the U.S. Centers for Medicare & Medicaid
Services announced that it would review the potential for
nationwide coverage of the Cologuard test. The agency is proposing
that the stool test be covered for people aged 50 to 85 who have no
symptoms of colorectal disease and who are at average risk for
"This is the first time in history that FDA has approved a technology and CMS has proposed national coverage on the same day," Patrick Conway, chief medical officer and deputy administrator for innovation and quality for CMS, said in the news release.
Last year, nearly 143,000 new cases of colorectal cancer were
diagnosed in the United States and almost 50,000 Americans died of
the disease, according to the U.S. National Cancer Institute.
A study published in March in the
New England Journal of Medicinefound Cologuard had a very
high accuracy rate in spotting colon cancer.
An accurate, noninvasive test would be a huge addition to the
fight against colon cancer, experts say. That's because one-third
of Americans fail to heed public health recommendations to undergo
invasive colonoscopy every 10 years starting at age 50, explained
study co-author Dr. Steven Itzkowitz, director of the
gastroenterology fellowship program at the Icahn School of Medicine
at Mount Sinai in New York City.
Commonly used stool tests such as FIT (fecal immunochemical
testing) rely on detecting blood in the stool. The new Cologuard
test checks for blood as well as abnormal DNA, "with the advantage
that some lesions, even cancers, don't bleed very much," Itzkowitz
But the Cologuard test also features a DNA analysis not included
in other fecal exams.
"By increasing the pick-up rate in this way," said Itzkowitz, "we found that the new test had a 92 percent sensitivity for detection of colorectal cancer. That kind of result is really unprecedented for a noninvasive stool-based screening."
The research was funded by Exact Sciences Corp., which is based
in Madison, Wisc.
To assess the potential of the DNA method, nearly 10,000 men and
women aged 50 and older were screened for colon cancer and
precancerous polyps at one of 90 sites across the United States and
Canada. All were considered at average risk for colon cancer.
Each patient was screened three ways: by means of a standard
colonoscopy; a commercially available fecal test (FIT); and the new
DNA test, which requires patients to collect their own stool sample
at home and mail it in for laboratory analysis.
In the end, colonoscopy screenings -- considered the gold
standard of colon cancer screening -- revealed colon cancer in 65
participants, while another 757 were found to have advanced
The new DNA test accurately detected 60 of those 65 cancers. The
FIT test spotted only 48 cancers, with an accuracy rate of 74
percent compared to 92 percent for the new test.
The DNA test was less accurate with respect to precancerous
lesions, spotting about 42 percent of cases. Yet that still topped
FIT, which detected roughly 24 percent of precancerous lesions.
Cologuard's sensitivity was 69 percent for precancerous polyps most
likely to progress to cancer versus 46 percent for the FIT
However, the DNA test was more likely to falsely suggest the
presence of cancer than either a colonoscopy or FIT testing.
"It [the DNA test] is not a perfect test," Itzkowitz acknowledged. "But neither is a colonoscopy. Also, I don't think we're saying that this test should be done as a replacement for a colonoscopy, but rather as an adjunct. Certainly if a person who does this test comes out with a positive reading then they will need to do a colonoscopy afterwards to confirm it."
Dr. Frank Sinicrope, a professor of medicine and oncology at the
Mayo Clinic in Rochester, Minn., said, "These data demonstrate the
superiority of stool DNA testing compared to FIT for colorectal
Sinicrope, who was not part of the study team, also suggested
that the Cologuard method might offer some advantages over standard
In particular, he pointed to the DNA test's success in
identifying certain advanced-stage polyps, noting such precancerous
growths are typically flat and "located in the right side of the
colon and are difficult to detect at colonoscopy."
Nevertheless, Sinicrope said there are still "important issues
that await further research." Those would include determining how
best to deal with false positive results and establishing how often
patients should take the DNA test to maximize its screening
For more information on colorectal cancer, visit the
U.S. National Cancer Institute.
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