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Colonoscopy vs. Cologuard: Which Is Right for You?

January 18, 2023

Colonoscopy prep is the stuff of nightmares for the over-45 crowd. From fasting to laxatives, it’s enough to make some avoid colonoscopies altogether.

For those set on avoiding colonoscopies, commercial tests like Cologuard or the fecal immunochemical test (FIT) offer an easier alternative. Done at home, these tests involve collecting a stool sample and mailing it to a laboratory for testing.

Even easier, EZ Detect™, which is now being sold at CVS stores, tests for microscopic blood in stool without having to collect and mail a sample. But how effective are they?

“Only 60 to 70% of people considered to be at average risk for colon cancer actually get screened,” says gastroenterologist Jeffry Nestler, MD, Hartford Hospital chief of gastroenterology and medical co-director of the Digestive Health Institute. “So we still have a long way to go.”

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So what does a colonoscopy do, anyway?

Colorectal cancer, often referred to simply as colon cancer, starts as a polyp. During a colonoscopy, these polyps can be removed, and colon cancer can be prevented. When caught early and treated, the survival rate is 90 percent.

Unfortunately, most people do not experience symptoms until colon cancer is advanced. By then, the cancer is harder to treat and requires surgery and chemotherapy, so early detection is key.

“I always recommend a colonoscopy because it’s a one-step test,” says Nestler. “You go in, look for polyps or cancer, and you remove those polyps or cancer at the same time. A colonoscopy is a colon-cancer-prevention test. We find precancerous polyps and we take them out so they never have a chance to turn into cancer.”

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Taking shortcuts

But because of the fear associated with colonoscopy prep, many people are turning to commercial tests like Cologuard or the fecal immunochemical test (FIT). Done at home, these tests involve collecting a stool sample and mailing it to a laboratory for testing. They are lauded as a replacement for having a colonoscopy performed by a physician. But does the science hold up?

Nestler says Cologuard or a FIT test require two steps, and they aren’t made to detect precancerous polyps. This makes them less preventive and more reactive.

The FIT tests for hidden blood in the stool – an early sign of cancer. Cologuard uses advanced technology to detect the DNA and blood cells released from altered cells, and claims to detect both precancer and cancer. EZ Detect™ tests for microscopic blood without having to handle any stool. Instead, an EZ Detect™ pad is placed in the toilet after a bowel movement and if it turns blue/green it indicates that blood was detected.

“Cologuard is 92% sensitive for colon cancer,” Nestler says, “but it is much less sensitive when it comes to colon polyps. It can miss these precancerous lesions.

“And,” he adds, “if you get a positive result, you have to do a colonoscopy anyway. If it is negative you still don’t know if you have a precancerous polyp waiting to grow into a cancer.”

The FIT test and EZ Detect™ colon tests are even less sensitive in detecting colon cancer and colon polyps.

The only test that actually “prevents” colon cancer is a colonoscopy because it finds the precancerous polyps and removes them.

Symptoms to watch for

Although most people do not experience symptoms of colon cancer until it is advanced, there are a few key indicators. These include symptoms such as:

  • A persistent change in your bowel habits, including diarrhea or constipation or a change in the consistency of your stool
  • Rectal bleeding or blood in your stool
  • Persistent abdominal discomfort, such as cramps, gas or pain
  • A feeling that your bowel doesn’t empty completely
  • Unexplained weight loss
  • Anemia

Getting screened sooner

Even if you aren’t experiencing any symptoms, it might be time to consider a colonoscopy. The American Cancer Society now recommends that the average person (anyone with no genetic markers or family history of colon cancer or polyps) starts getting colonoscopies by age 45 (it was previously 50).

People in these groups may benefit from earlier or more frequent testing:

  • People of African American or Ashkenazi Jewish descent.
  • Those with Crohn’s disease or ulcerative colitis.
  • Anyone with a genetic syndrome such as familial adenomatous polyposis (FAP) or hereditary nonpolyposis colorectal cancer (Lynch syndrome).