Stool tests like Cologuard are gaining popularity over colonoscopy. Which should you get?

What if you didn't have to get a colonoscopy every decade from ages 45 to 75?

No, this isn't an excuse to skip screening for colon cancer, which has been proven to save lives. But there are several alternatives, which most people don't know much about.

They are called stool tests and they are just as gross as you might imagine, but they can be done at home, mailed into a lab and don't require any special preparation, unlike colonoscopy.

Over time, stool tests – including fecal immunochemical tests, or FIT, and the heavily advertised Cologuard – can be just as effective at saving lives, and they avoid some of the down sides of colonoscopies, experts say. The main issue with stool tests is they have to be done more often: FIT annually, and Cologuard every three years.

No test is objectively better than the others. The United States Preventive Services Task Force recommends colonoscopy and stool tests equally for folks ages 45 to 75 and selectively up until 85 for someone who is otherwise healthy.

"The best colorectal cancer screening test is the one you actually choose to take," said Dr. Barnett Kramer, a member of the Lisa Schwartz Foundation for Truth in Medicine, who retired as director of the National Cancer Institute's division of cancer prevention.

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Here are the advantages and disadvantages of the different approaches.

Pros and cons of colonoscopy

Colonoscopy is considered the gold standard. If someone has symptoms like bleeding or problems crop up with other tests, people need to get a colonoscopy to figure out what's going on.

Routine colonoscopies should be done once a decade. Today, 60% of Americans are up to date on colonoscopies, with another 11% choosing a different testing method, according to the CDC.

Colonoscopies also have drawbacks.

Although the Affordable Care Act requires colonoscopies, like other screening tests, to be offered at no cost to the patient, people are sometimes surprised with a bill for anesthesia after a colonoscopy, Kramer said. (In China, they often perform the procedure without anesthesia, but in the U.S., most doctors will refuse to do one unless their patient is out and less likely to squirm due to discomfort, he said.)

Colonoscopies are unquestionably the best test for finding polyps, but it's not clear that should be the goal of screening, said Dr. Douglas Robertson, a professor at the Dartmouth Geisel School of Medicine and chief of Gastroenterology at the VA Medical Center in White River Junction, VT.

"I don't want to discourage people who have a history of polyps from getting exams and finding polyps," said Robertson, who runs a large trial comparing colonoscopy to FIT for the Veterans Administration.

Polyps are growths that may or may not eventually become cancerous, and more than half the population has them.

"Common sense tells you that the vast majority of people even with polyps aren't marching off to cancer," he said.

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Cologuard stool testing may be an option

Cologuard advertises heavily on TV and has raised awareness about the need for colorectal cancer screening. This test, which requires people to collect a poop sample and mail it in, looks for certain high-risk genetic mutations as well as blood in the stool.

A positive Cologuard test could represent genetic mutations in the stool and that might prompt some doctors to do more follow up testing even after a clean colonoscopy. But the need or value of that follow-up is entirely unclear, Robertson said.

As a one-time test, Cologuard will detect more cancers than FIT, Robertson said, but over time, if done annually in the case of FIT and every three years for Cologuard, "it's a close call. If anything, the models tend to favor FIT," he said.

Cologuard is easy for patients to use and easy for doctors to interpret the results, said Dr. Casey Allen, a surgical oncologist at Allegheny Health Network in Pennsylvania.

"There's an incentive to the patient and to the provider," he said.

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Why FIT may be the best of all

FIT is a lot like Cologuard in that people often have to ship off a stool sample, though some doctors can collect the sample with a rectal exam.

The main downside to FIT, which looks solely for blood in the stool, is that people have to take them annually, and some health care providers don't trust their patients to stay up to date.

"When given a choice, the preference in some countries appears to be for FIT," as opposed to either colonoscopy or Cologuard, Kramer said. "I guess because it is less invasive and because you can do it at home."

Roughly 5% to 7% of FIT tests will lead to the need for a colonoscopy, compared with 13% to 15% of Cologuard tests, he said.

FIT is undeniably the cheapest option.

In a recent study, Allen and his colleagues found FIT cost just over $17 a year, while Cologuard cost Medicare about $350. (Private insurers are often charged far more.) A colonoscopy can easily run $10,000. Under the Affordable Care Act, all screening tests must be covered by insurers.

"There's a substantial cost savings without changing patient outcomes," said Dr. Pavan Rao, a general surgeon at Allegheny General Hospital, who led the research. "The driving force now is to provide education to both patients and primary care providers … and to do a good job of educating them on the costs versus the benefits of the two tests."

With Cologuard and FIT, the cost of a follow-up colonoscopy, if needed, hasn't always been completely covered by insurance, but new rules suggest it will be going forward.

In the future, it's possible that insurers may require patients to share the costs of more expensive tests that haven't been proven more effective than cheaper options, Allen said.

Major health care organizations, including the Veterans Administration and Kaiser Permanente, offer FIT tests, Robertson said, with Kaiser effectively encouraging people to come back every year. Kaiser has shown a 50% reduction in colorectal cancer mortality among its patients since they started using FIT back in 2008.

Both Robertson and Kramer get annual FIT tests themselves.

"I'm a FIT enthusiast," Robertson said.

Contact Karen Weintraub at

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This article originally appeared on USA TODAY: Colonoscopy, Cologuard, other stool tests: Which detects colon cancer?