More than 100,000 new cases of colorectal cancer are diagnosed in the U.S. each year, making it one of the most common forms of cancer. But while the condition is common, it’s also very preventable and treatable when detected early through colorectal cancer screenings.
If you’ve ever read about colorectal cancer screenings, you’re probably familiar with a type of screening known as a colonoscopy. That type of screening is considered the gold standard, but it’s not the only option these days.
Why Colorectal Cancer Screenings Are Important
First things first, why are these screenings so important in the first place? Like most forms of cancer, colorectal cancer is most easily treated when it’s discovered in its earliest stages.
When colorectal cancer is detected in a localized stage, meaning it hasn’t spread beyond the original site, it has a five-year survival rate of around 90 percent.
But there’s even better news—in many cases, colorectal cancer can be prevented altogether with the help of colorectal cancer screenings. That’s because screenings can detect the presence of precancerous polyps, which can then be removed before they develop into cancer.
Understanding the Options for Colorectal Cancer Screenings
Colorectal cancer screenings are recommended for most adults beginning at age 45. What are the options?
Colonoscopy remains the gold standard for screening because it’s the only method where precancerous polyps can be removed from either the colon or the rectum at the time of screening. During the procedure, a thin, lighted tube is used to check for polyps throughout the entire rectum and colon.
But for people who are at an average risk of cancer or who can’t carve out the time for a colonoscopy and the necessary pre-surgical bowel prep, at-home screenings may be an option. There are two main types—FIT (fecal immunochemical test) and FIT-DNA, also known as Cologuard.
Both work similarly, checking for the presence of blood in the stool, but Cologuard also looks for DNA markers that may indicate the presence of either colorectal cancer or precancerous polyps.
How Accurate are At-Home Tests?
In comparison with colonoscopy, which has a detection rate of around 95 percent, at-home colorectal cancer screenings are slightly less accurate.
Cologuard can detect 92 percent of cancers but only 42 percent of large precancerous polyps. Cologuard is better at detecting cancer than FIT (92 percent versus 74 percent for FIT), but the false positive rate is higher. Cologuard has a 13 percent false-positive rate, and that rate increases as people age.
Because they look only at fecal samples, at-home screenings need to be repeated more frequently than colonoscopy. And if colorectal cancer is suspected based on a stool test, a colonoscopy will be needed to confirm the diagnosis and remove polyps, if present.
