Colon Cancer: At-home Test Uses DNA to Spot Hidden Dangers

Ah, the colonoscopy.

The screening test for colorectal cancer—and the not-so-fun preparation that must precede it—is enough to make most people squirm in anticipation. Although it’s a recommended procedure for everyone after turning 50, many forgo the test because of what it entails.

Colorectal cancer is the third most common cancer that affects both men and women in the United States, with some 140,000 people diagnosed each year. Although the disease is highly preventable with proper screening, fewer than half of those who should get checked for it actually do.

A fairly new at-home test might make getting screened a whole lot easier.

Approved by the Federal Drug Administration in 2014, Cologuard uses DNA to help spot potentially deadly tumors and growths.

The test—available by prescription—involves little more than collecting a stool sample and sending it to a lab. While it cannot tell you if you have cancer, it detects the presence of red blood cells and DNA mutations that may indicate the presence of abnormal growths that could be cancer or precursors to cancer.

A positive result comes with a recommendation to have a diagnostic colonoscopy.

Cologuard does not replace colonoscopy, which is still considered the gold standard for detecting cancers of the colon or the rectum. “But as a screening test, it’s a good tool,” says Dr. Bunan Alnaif, an obstetrician/gynecologist at Western Branch Center for Women in Chesapeake.

Basically, Cologuard might help spur someone to visit a doctor to find out whether he or she really has cancer.

Alnaif, who began recommending Cologuard to patients about a year ago, said she’s had patients who had a positive test and then went on to get a colonoscopy. For one woman, Cologuard “saved her life,”
Alnaif says. The test indicated there was a problem —and the subsequent colonoscopy found precancerous polyps that were immediately removed.

Colorectal cancer caught early—treated by having precancerous polyps removed, for example—has a five-year survival rate of more than 90 percent. But if the cancer is found at a later stage, that survival rate drops to less than 30 percent. That means someone has only a 30 percent chance of living five years past diagnosis.

“With colorectal cancer, early detection is everything,” Alnaif says. “It’s a very prevalent cancer. But it’s a preventable cancer if we catch it early enough. Our aim is to get them diagnosed early enough so we can give them those years.”

Doctors say there’s no better time to remind people to get screenings than during the month of March, which was designated Colorectal Cancer Awareness Month by former President Bill Clinton in 2000.

The American Cancer Society recommends that adults start getting colorectal screenings at age 50, with colonoscopy being the most comprehensive test. A colonoscopy allows a doctor to look at the inner lining of the large intestine (the rectum and colon), helping find ulcers, polyps, tumors and areas of inflammation and bleeding. If a precancerous growth is found, it can be taken out right then and there.

The Centers for Disease Control and Prevention estimates that if everyone followed the current colorectal screening guidelines, at least 60 percent of colorectal deaths could be avoided. As it stands now, more than 50,000 Americans die from colorectal cancer every year. It’s the second leading cause of cancer-related deaths in this country.

Dr. Joseph Frenkel, a colorectal surgeon with Bon Secours Surgical Specialists in Suffolk, said there’s actually been a big decrease in colorectal cancers in the past 10 years, thanks to improvements in the screening tests. Colonoscopies are more detailed than they used to be and Cologuard has been shown to be more accurate at detecting cancerous tumors than traditional stool blood tests.

If people are put off by the thought of colonoscopy, it’s usually because of the prep work that’s required. Called bowel prep, it involves a clear, liquid diet or drinking a special solution for one to two days to clean out the colon. The colonoscopy itself is done under sedation.

A clean colonoscopy means you likely don’t need one for another 10 years. If polyps are found, then not for three to five years. If one chooses to try Cologuard and it’s negative, the recommendation is to repeat it every three years. Just to be on the safe side.

Frenkel says Cologuard could be useful for patients, such as the very elderly, who might not be medically fit to undergo a colonoscopy.

He, too, has had a patient who had a positive Cologuard and then had a colonoscopy, which revealed three small polyps that were immediately removed.

“Not all polyps turn into cancer, but some do,” Frenkel says. “By removing them, you remove that risk of developing cancer.”