I want to walk you through the importance of colorectal cancer screening and explain the different options available.
Screening for colorectal cancer saves lives. According to the U.S. Preventive Services Task Force (USPSTF) guidelines updated in 2021, we now recommend that most average-risk individuals start screening at age 45, continuing through age 75. Screening decisions for those aged 76 to 85 should be based on individual health factors. It’s important to note that these recommendations apply only to people at average risk.
Who is considered average risk?
If you’ve had colon polyps, a history of inflammatory bowel disease, radiation in childhood or a known genetic cancer syndrome, you’re not considered average risk. A first-degree relative with colon cancer also puts you into a higher-risk category, requiring different recommendations. But if you only have more distant relatives with colon cancer, you're usually still considered average risk.
When it comes to screening methods, there are several options:
Visualization-based screening tests
- Colonoscopy is the gold standard. It detects both cancers and precancerous polyps. It’s done every 10 years for most average-risk people, but it requires bowel prep, anesthesia and transportation. It carries small risks of bleeding and perforation.
- CT colonography (also called virtual colonoscopy) is a good option for some. It uses a CT scan after inflating the colon with air. It doesn’t need anesthesia, but still requires bowel prep and can find things outside the colon, which sometimes leads to additional testing.
- Flexible sigmoidoscopy looks at only the lower colon. It can be done without anesthesia and has been shown to reduce colorectal cancer deaths. It’s often combined with FIT testing for better coverage.
Stool-based screening tests
- High-sensitivity guaiac fecal occult blood testing looks for hidden blood in the stool. It's supported by randomized trials but needs to be done yearly, requires dietary restrictions, and isn’t great at detecting precancerous polyps.
- FIT (fecal immunochemical testing) is an antibody test for blood in stool. It’s more sensitive than guaiac tests and also needs to be repeated every year. The main downside is that it can still miss large precancerous polyps.
- Cologuard combines FIT with DNA testing for cancer-related changes in the stool. It’s more sensitive than FIT but also more likely to produce false positives, meaning more follow-up colonoscopies. It’s usually repeated every 1 to 3 years.
Tests not currently recommended
There are blood-based tests like Shield and SEPT9 that are available but not currently recommended by the USPSTF. These tests have lower sensitivity for early-stage cancer and precancerous lesions compared to the stool- and scope-based options.
What the latest research says
A large study from Scandinavia — the NordICC trial — showed that simply inviting people for colonoscopy reduced colorectal cancer risk modestly. For those who actually underwent colonoscopy, cancer incidence was reduced by 31%, and death from colorectal cancer dropped by 50%.
Conclusion
Colorectal cancer screening offers several effective options — and the most important thing is to choose a method and stick with it. Getting screened regularly can help detect cancer early, when it’s most treatable. Talk with your provider about what screening option is right for you.
Learn more about colorectal cancer screening at Northside Hospital.
