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The Truth About Cologuard Tests

Cologuard is spending millions on advertising, but it’s impossible for patients to get all the information they need in a TV commercial.  It’s true, Cologuard offers benefits of comfort and convenience, but the Cologuard test is not recommended by GCSA physicians as a replacement for a colonoscopy.

Colon cancer claims over 50,000 lives every year and is the 2nd most common cause of cancer death in the US. Colon cancer is preventable, treatable, and beatable – but only with early and accurate detection.

Any colon cancer screening is better than no screening, but patients should know the pros and cons before making a final decision.

Types of Colorectal Cancer (CRC) Screening

Because colon cancer begins as growths called polyps, finding and removing polyps is the best way to prevent colon cancer.  There are three types of CRC screening:

  1. Colonoscopy – 95% of large polyps detected
  2. Stool DNA (Cologuard) – 42% of large polyps detected
  3. Fecal Immunochemical Test (FIT) – 30% of large polyps detected

Colonoscopy is the gold standard for finding polyps. If polyps are found during a colonoscopy, they are removed during the same single procedure.  This eliminates the need for additional procedures or tests.

If polyps are found through FIT or a Cologuard test, a colonoscopy must be performed to remove the polyps.

Unfortunately, the majority of large polyps go undetected with FIT and Cologuard tests.  When polyps aren’t found and removed it increases the risk of developing colon cancer.

Cologuard Test: Detection Not Prevention

Cologuard vs Colonoscopy - Detection Rate of Precancerous PolypsThe Cologuard test is designed to detect cancer not prevent it.  Cologuard can only detect 42% of large polyps, while a colonoscopy can detect 95% of large polyps.

When polyps are detected during a colonoscopy they are removed at the same time.  If polyps are detected with Cologuard, a colonoscopy must be performed to remove them.

The majority of large precancerous polyps cannot be detected with Cologuard.  This may give patients a false sense that they are preventing colon cancer by taking the Cologuard test.

Cologuard Test Colonoscopy Alternative

Save Time & Money

If you have a high risk of colorectal cancer, which includes:

  • a family history of colon cancer
  • present symptoms
  • previous colonoscopy finding of polyps

You should skip the Cologuard test.

This will save you time, money, and the frustration of undergoing both tests since a colonoscopy is needed for high-risk patients.

If your primary care provider recommends Cologuard, and you are at high risk, you should consult with a specialist before undergoing the test.

How does the Cologuard test work?

The Cologuard test is a stool DNA test that looks for microscopic blood in the stool and altered DNA.  It’s performed using an at-home kit that includes a container for a stool sample. That sample is then shipped to a lab for testing.

How Accurate is the Cologuard test?

Cologuard can detect 92% of cancers but only 42% of large precancerous polyps.

Cologuard is better at detecting cancer than FIT (92% vs 70% for FIT), but the false positive rate is higher.  Cologuard has a 12% false positive rate, and that rate increases as people age.

Cologuard is less accurate than a colonoscopy at detecting polyps of any size.  A colonoscopy can detect 95% of large polyps and Cologuard only 42%.

Cologuard FAQ

Can Cologuard detect polyps?

Yes, Cologuard can detect polyps.  However, the detection of large polyps (the precursors to colon cancer) is less than half as accurate as a colonoscopy.

Is the Cologuard test as effective as a colonoscopy?

No, the Cologuard test is not as effective as a colonoscopy.  Detecting and removing polyps is critical to colon cancer prevention, and Cologuard only detects large precancerous polyps 42% of the time.  A colonoscopy detects the same polyps 95% of the time and they are removed during the same procedure.

What does it mean if your Cologuard test is positive?

If the Cologuard test is positive, it may mean that colon cancer or polyps are present. After a positive Cologuard test a colonoscopy is required for a definitive answer.  The Cologuard test has a 12% false positive rate, which means 1 in 10 positive tests will incorrectly identify cancer or polyps.

Can Cologuard detect cancer?

Yes, the Cologuard test can detect cancer 92% of the time.  However, prevention of colon cancer is better than identifying it once you have it.  The best way to prevent colon cancer is by identifying and removing precancerous polyps that don’t turn into cancer later.  Cologuard only finds 42% of large, dangerous polyps that can turn into colon cancer.

Can I use Cologuard instead of a colonoscopy?

Cologuard is not designed to be a replacement for a colonoscopy, even though advertisements may suggest otherwise.  58% of the time, dangerous precancerous polyps are not detected with Cologuard, which is significantly less effective than a colonoscopy. However, Cologuard may be an option for some patients who insist on not getting a colonoscopy or those not healthy enough to have a colonoscopy.  Even a 42% chance of detection is better than no detection at all.

How long is Cologuard good for?

A Cologuard test should be done every three years rather than annually due to the higher cost and false positive rates compared to an annual FIT.  More research is needed to determine how often the Cologuard test should be done.

What is the false positive rate of Cologuard?

The false positive rate for Cologuard is 12% or a little over 1 in 10.

Is a stool sample as good as colonoscopy?

FIT and Cologuard tests performed using stool samples are not as effective at identifying the large precancerous polyps that lead to colon cancer. FIT and Cologuard tests are more effective than doing no testing at all.

How accurate is stool test for colon cancer?

There are two types of stool tests for colon cancer. Fecal Immunochemical Test (FIT) and Stool DNA (Cologuard).  FIT detects 70% of colon cancers and 30% of large colorectal polyps. Stool DNA/Cologuard detects 92% of cancers and 42% of large colorectal polyps.

How much does Cologuard cost?

The cost of Cologuard is around $500.  Part of that cost may be covered by some insurances depending on your plan, co-pay, and deductible.  Diagnostic testing is subject to deductibles and coinsurance.

Screening colonoscopies are not subject to copays and deductibles and usually have no out of pocket costs for patients.

What can Cologuard detect?

Cologuard can detect 92% of cancers and 42% of large precancerous polyps, the precursor to colon cancer.

Who is Cologuard good for?

Cologuard may be an option for patients who insist on not having a colonoscopy or who are not healthy enough for the procedure.  Some patients may decide that the risks associated with a colonoscopy outweigh the benefits of increased detection.

Any test for colon cancer is better than no test at all.  If the Cologuard test is positive, a colonoscopy will be necessary.

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