The U.S. Food and Drug Administration has approved an at-home colon cancer test. Called Cologuard , it is the first stool-based screening test that detects certain DNA mutations and red blood cells that could be indications of colorectal cancer, according to the FDA. The test, which is ordered through a doctor's office, can be done at home.
"Unlike many other screening options, Cologuard does not require medication or dietary restrictions, or bowel preparation prior to taking the test," the manufacturer says.
The FDA says Cologuard could be used to help determine who is at risk of developing colorectal cancer at its earliest stages when the cancer is still asymptomatic. The agency approved the test this week.
Most cases of colorectal cancer begin as small polyps attached to the walls of the large intestine or rectum. Colorectal cancer primarily affects men and women over the age of 50. And in most situations it is preventable. If caught in time, the FDA says at least 60% of colorectal cancer deaths could be avoided.
The new stool-based test detects certain abnormalities associated with colorectal cancer cells. Patients who test positive with Cologuard would be advised to undergo further tests, including a colonoscopy.
"This approval offers patients and physicians another option to screen for colorectal cancer," said Alberto Gutierrez, director of the Office of In Vitro Diagnostics and Radiological Health at the FDA's Center for Devices and Radiological Health. "Clinical data showed that the (new) test detected more cancers than a commonly used fecal occult test."
Fecal occult blood tests, or fecal immunochemical tests, are previously approved screening tests that can be done once a year at home. The American Cancer Society recommends people with an average risk for colorectal cancer also have a flexible sigmoidoscopy every five years or a colonoscopy every 10 years.
Although it adds another method for detecting some cases of colorectal cancer, the new at-home test has both pros and cons, says Dr. Won Kyoo Cho, chief of gastroenterology/hepatology at MedStar Washington Hospital Center in Washington.
"When it comes to spotting more abnormalities the test is very good. The Cologuard picks up about 92.3% of abnormalitites, compared to 74% with the FIT (fecal immunochemical test)."
But Cho warns, "The downside is the new test was not as good at finding 'true negatives.' ” Cologuard correctly identified a negative result in 87% of patients, the FDA says; the fecal immunochemical test correctly identifies negative results about 95% of the time.
"That means you may be picking up abnormalities, but it doesn't necessarily mean those abnormalities are cancerous, so the false positives are higher," Cho says. "Many people who test positive on the test may be worried for no reason."
The approval of Cologuard does not mean current colorectal cancer screening guidelines have changed. The FDA notes that stool DNA testing is not currently recommended to screen for colorectal cancer by the U.S. Preventive Services Task Force. The task force still believes patients between the ages of 50 to 75 should be screened using fecal occult blood testing, a sigmoidoscopy or a colonoscopy.
A colonoscopy is the "gold standard" in colorectal cancer detection.
"(Cologuard) doesn't really detect polyps that could be the beginning of colon cancer," Cho said. "When you go in with a colonoscopy, you can snip those polyps out immediately. Done. But if you miss those polyps and they grow in the colon, you could be facing serious surgery, or even the possible spread of the cancer."
At this point, the main issue with Cologuard is cost. According to Cologuard's manufacturer, one test costs as much $600. But the FDA noted on the same day of the test's approval, the Centers for Medicare and Medicaid Services issued a proposed national coverage, meaning Medicare will pay for the test once every three years for beneficiaries who meet a certain criteria.
"This is the first time in history that FDA has approved a technology and CMS has proposed national coverage on the same day," said Patrick Conway, chief medical officer and deputy administrator for innovation and quality for the Centers for Medicare and Medicaid Services. "This parallel review … will provide timely access for Medicare beneficiaries to an innovative screening test to help in the early detection of colorectal cancer."
Cho adds, "The fecal tests we use now cost as little as $20, which means you can afford to have one done every year. But hundreds of dollars – no wonder Medicare will only pay for it every three years."