Colonoscopy vs. Cologuard – Which Screening Test is Best?
in Denver

March is Colorectal Cancer Awareness Month. Colorectal cancer is the third most commonly diagnosed cancer in the U.S., but it’s also one of the most preventable cancers. Symptoms of colorectal cancer typically do not occur until the cancer has progressed to an advanced stage. That’s why screening is so critical. If colorectal cancer is detected at an early stage, survival rates are often greater than 90%.

People who are at average risk for colorectal cancer should start regular screening at age 45. Those who have risk factors for the cancer, such as a family history of colorectal cancer, being African American, being diagnosed with irritable bowel disease or having a genetic syndrome, should speak with their doctor about being screened at an earlier age.

There are several colorectal cancer screening tests available. Patients can do a stool-based test, such as Cologuard, that looks for signs of cancer in a person’s stool. The other option is to complete a colonoscopy, which is a visual exam that looks for polyps in the colon and rectum. 

What is a stool test?

These tests are used to detect blood or DNA change in the stool. The stool tests used to detect blood in the stool are the guaiac-based fecal occult blood test (gFOBT) and the fecal immunochemical test (FIT).

Cologuard is a stool test done at home that detects DNA that has changed in the stool leading to potential pre-cancerous and cancerous colon polyps.

What is a Colonoscopy?

Colonoscopy is considered the gold standard for colorectal cancer screening. It is the only test that can detect and prevent cancer. The U.S. Multi-Society Task Force on Colorectal Cancer classifies colonoscopy as a tier-one screening test.

A colonoscopy is a short procedure that involves a gastroenterologist inserting a colonoscope (a long flexible tube with a light and small camera) and guiding it to the end of the colon. If polyps are found, the doctor will painlessly remove them and send them to a lab for analysis.  

How does Cologuard compare to Colonoscopy?

• Cologuard can detect cancer, but it cannot prevent cancer from developing. A colonoscopy is the only screening test that can do both.
• Colonoscopy is more sensitive at detecting cancerous and pre-cancerous colon polyps. In fact, Cologuard can miss up to 8% of cancerous colon polyps and 42% of pre-cancerous polyps.
• Cologuard tests are associated with a 13% false-positive rate. This means that 1 in 10 Cologuard tests will incorrectly identify colorectal cancer and polyps.
• Cologuard may be marketed as more convenient, but if a Cologuard test comes back positive, patients will need to have a colonoscopy to remove any polyps.
• Negative Cologuard tests should be repeated every three years. If no polyps are found in the procedure, a colonoscopy will usually not need to be repeated for another 10 years, if the patient is at average risk.
• Because of the 13% false-positive rate of Cologuard tests, patients’ insurance deductibles may increase over the 10-year colorectal cancer screening period.
• People who are at higher risk for developing colorectal cancer or those experiencing concerning GI symptoms are not eligible for stool-based tests like Cologuard.

A screening colonoscopy is stunningly effective. It can save your life. If you are approaching 45 years of age, it’s time for a colonoscopy. Learn more about scheduling a colonoscopy with one of our gastroenterologists practicing in Denver, Castle Rock and Parker.