Can At-Home Screening Tests Replace a Colonoscopy?
January 24, 2023
No one looks forward to a colonoscopy. Two at-home tests eliminate the invasiveness and prep of getting a colonoscopy. But are these screenings as effective as colonoscopy in detecting colorectal cancer and precancerous polyps?
Why Is Colorectal Cancer Screening Important?
Each year, approximately 150,000 Americans are diagnosed with colorectal cancer and more than 50,000 Americans die from the disease. Colorectal cancer is the second-most common cause of cancer death in the country. However, the disease is highly treatable when detected early through screening.
During a colonoscopy, a doctor passes a camera on a flexible tube into the rectum to view the inside of the colon for precancerous polyps and other abnormalities. Not only is the test invasive, many people find the prep for the procedure to be unpleasant, as it involves taking laxatives and restricting yourself to a liquid diet for an entire day to clear out your system. Yet despite any unpleasantness, colonoscopy remains the gold standard for colorectal cancer screening.
At-Home Screening vs. Colonoscopy
Two noninvasive, at-home screening tests are available as an alternative to a colonoscopy. They require the collection of a stool sample at home to mail to a lab for examination:
- Fecal Immunochemical Test (FIT): checks for blood associated with polyps and colon cancer in the stool sample.
- Cologuard FIT-DNA test: checks for DNA markers and blood associated with polyps and colon cancer in the stool sample.
“Colonoscopy is the preferred colorectal cancer screening method,” says Gregory Cooper, MD, a gastroenterologist who is Co-Program Leader for Cancer Prevention and Control at UH Seidman Cancer Center and the Case Comprehensive Cancer Center. “Whereas colonoscopy can detect at least 95% of large polyps – the polyps most likely to turn into cancer – Cologuard detects 42% and FIT testing detects 24%. Because polyp removal is so important to colorectal cancer prevention, colonoscopy is superior to the other screening methods.”
Significantly, when polyps are found during a colonoscopy, the doctor removes them during the same procedure, which eliminates the need for additional tests or procedures. In this way, colonoscopy not only detects polyps and colorectal cancer, the procedure can also prevent colorectal cancer from developing in the first place.
In contrast, Cologuard and FIT tests can only detect polyps and colorectal cancer. When these tests indicate the possible presence of polyps or cancer, a colonoscopy must be performed later on to remove the polyps. Yet Cologuard and FIT do not detect the majority of precancerous polyps. Undetected, unremoved, precancerous polyps increase a person’s risk of developing colorectal cancer.
When is At-Home Colorectal Cancer Screening Appropriate?
Dr. Cooper says, “Though colonoscopy is the preferred method for colorectal cancer screening, the stool-based tests are useful in certain situations. For example, an at-home test can be appropriate for some patients who are on anticoagulants, as those individuals are at higher risk for experiencing bleeding during colonoscopy. Also, some patients may benefit from an at-home test because they are at higher risk for experiencing complications from the sedation itself.”
Furthermore, due to the required sedation, patients must arrange for their own transportation to and from their colonoscopy. Dr. Cooper says that some patients simply do not have access to a ride and may opt for an at-home screening option for that reason.
Cologuard or FIT?
Of the at-home screening tests, Dr. Cooper says Cologuard is the better option overall.
“Cologuard is more accurate than FIT at detecting precancerous polyps because those polyps tend not to bleed. Whereas FIT tests can only detect blood in a stool sample, Cologuard detects blood and DNA markers associated with both precancerous polyps and cancer. Also, Cologuard is better at detecting colorectal cancer itself, detecting more than 90% of cancerous lesions in the colon compared to about 75% to 80% for FIT.”
Another advantage of Cologuard is that if you get a negative result, you don’t have to get another Cologuard test for three years, whereas FIT tests are typically repeated annually. Furthermore, Cologuard is supported by a navigator system that contacts the patient with reminders for them to complete and send in their test, which makes for better compliance than that seen with FIT testing.
The board-certified gastrointestinal physicians and surgeons at University Hospitals are leaders in screening, diagnosing, managing and treating all types of colon polyps, colon cancer and other gastrointestinal conditions. Learn more about colon cancer screening services at University Hospitals.
Tags: Cancer, Colonoscopy, Colorectal Cancer, Screenings