Colorectal cancer remains one of the most common cancers in both men and women, and doctors continue to see an alarming rise in cases among younger adults. The good news is that colorectal cancer is also one of the most preventable cancers because screening can detect and remove precancerous polyps before they ever turn into cancer.
The latest colorectal cancer screening guidelines from the American Cancer Society reflect the growing number of screening options available today, including stool-based tests and newer blood-based tests. The updated guidance also includes a newer multitarget stool RNA test, while blood-based screening is now recognized as an option for some people who are unwilling or unable to complete other recommended screening tests.
For most adults at average risk, colorectal cancer screening should begin at age 45. While there are more ways to screen than ever before, the tests have important differences, particularly when it comes to finding and removing precancerous polyps.
Why is colonoscopy still an important colorectal cancer screening test?
“Colonoscopy is still the gold standard for colorectal cancer screening,” says Alexandra Columbus, MD, MPH, FACS, colon and rectal surgeon, Tufts Medical Center. “Colonoscopy is unique because it’s both diagnostic and therapeutic. We can detect precancerous polyps and remove them during the same procedure, which can actually prevent cancer from developing.”
That is one of the biggest differences between colonoscopy and other screening methods. Stool and blood tests can detect signs that may indicate colorectal cancer or precancerous changes, but they cannot remove a polyp. If one of these tests produces an abnormal result, a follow-up colonoscopy is needed.
Colonoscopy is typically performed every 10 years for people at average risk, while other screening tests need to be completed more frequently. The right approach can depend on a person's risk factors, preferences and ability to complete the test consistently.
What are the new colorectal cancer screening options?
The updated guidelines include several screening options for people at average risk, including colonoscopy, stool-based tests, CT colonography and flexible sigmoidoscopy. Stool-based options include annual fecal immunochemical testing (FIT), annual high-sensitivity guaiac-based fecal occult blood testing (gFOBT), multitarget stool DNA testing every three years and the newer multitarget stool RNA test every three years.
Blood-based screening tests are also included in the updated guidance, but they are not currently considered a preferred screening option. They are intended primarily for people who are unwilling or unable to complete a stool-based test or visual screening exam.
Dr. Columbus says the newer blood-based tests may still play an important role for some patients.
“These tests may be helpful for patients who are unwilling or unable to undergo colonoscopy. Some people may have medical reasons they can’t have the procedure, difficulty tolerating the bowel preparation, transportation concerns, or simply strong reluctance toward invasive testing. The important thing is that some screening is far better than no screening.”
Alexandra Columbus, MD, MPH, FACS
The availability of more screening options may help more people get screened. The most effective screening strategy, however, is one that a person is willing and able to complete on schedule.
When should colorectal cancer screening begin?
For most adults at average risk, screening should begin at age 45 and continue regularly. Adults should talk with their health care provider about which screening method makes the most sense for them based on their health history and risk factors.
People with a family history of colorectal cancer, certain genetic conditions, inflammatory bowel disease or a personal history of colorectal cancer or certain polyps may need to begin screening earlier or be screened more frequently.
It's also important to understand that screening recommendations apply to people who do not have symptoms. People with symptoms such as rectal bleeding, unexplained weight loss, abdominal pain or changes in bowel habits should talk with their doctor right away, regardless of age. They may need diagnostic evaluation rather than routine screening.
What’s the most important thing to know about colorectal cancer screening?
Having more screening options doesn't change the importance of getting screened. Colorectal cancer can often be prevented when precancerous polyps are found and removed, and finding cancer earlier generally makes it easier to treat.
“The biggest message we want to send is simple: don’t delay screening,” says Dr. Columbus. “Early detection truly saves lives, and the best screening test is ultimately the one that gets done consistently.”
For people at average risk, the most important step is to start screening at 45 and stay up to date. If a stool or blood-based screening test comes back abnormal, follow-up colonoscopy is essential.
If you are scheduled for a colonoscopy or want to know what to expect, read our guide to colonoscopy preparation and recovery.
