Health Column: DNA test can screen for colorectal cancer

Between the dreaded preparation and procedure itself, no one would call getting a colonoscopy a barrel of laughs.

But reluctant would-be patients should take heart: In August, the U.S. Food and Drug Administration approved Cologuard, the first non-invasive DNA screening test for colorectal cancer.

According to an FDA press release, Cologuard uses stool samples to “detect the presence of red blood cells and DNA mutations that may indicate the presence of certain kinds of abnormal groups that may be cancers such as colon cancer or precursors to cancer.”

Patients with positive test results are then advised to undergo a colonoscopy.

“What’s great about this test is that it’s non-invasive,” said Dr. Eyad Ali, a Hampton Bays gastroenterologist and assistant clinical professor of medicine at Stony Brook University. “It can be done in the privacy of your own home and there’s no prep involved.”

According to the Centers for Disease Control and Prevention, colorectal cancer primarily affects people 50 and older. Among cancers that affect both men and women, it’s the second-leading cause of cancer-related death in the United States.

But it’s also highly preventable, provided you get screened every five to 10 years beginning at age 50. Most colorectal cancers begin as abnormal raised or flat tissue growths on the wall of the large intestine or rectum, FDA officials said.

Dr. Ali, who said he offers Cologuard to patients who have never had a colonoscopy or who express hesitation about having one, called the new test “pretty accurate.”

In a clinical trial that screened 10,023 subjects, the FDA said, Cologuard “accurately detected 92 percent of colorectal cancers and 42 percent of advanced adenomas.”

But as these statistics demonstrate, Dr. Ali pointed out, the test isn’t perfect — and false positives are always possible. Indeed, the FDA said Cologuard’s approval “does not change current practice guidelines for colorectal cancer screening.”

Still, Dr. Ali said, “Anything that gets somebody in for a screening is a plus. I think [Cologuard] is an open door for people to at least get screened and start a conversation with their doctor.”

Think Cologuard might be right for you? The Centers for Medicare & Medicaid Services has proposed covering the test every three years for Medicare beneficiaries who meet all of the following criteria:

• between 50 and 85 years old;
• asymptomatic (no signs or symptoms of colorectal cancer, like gastrointestinal pain, blood in stool, positive guaiac fecal occult blood test or fecal immunochemical test); and
• average risk of developing colorectal cancer (i.e. no personal history of adenomatous polyps, of colorectal cancer or inflammatory bowel disease, including Crohn’s and ulcerative colitis; no family history of colon cancers or adenomatous polyps, familial adenomatous polyposis or hereditary nonpolyposis colorectal cancer).

March is National Colorectal Cancer Awareness Month. Click here to learn more about the disease, including fast facts and prevention guidelines.