Colorectal cancer screening – testing to look for cancer before symptoms start – can help save lives. Regular screening can find colorectal cancer early when it’s small and might be easier to treat. There are several different screening options for colorectal cancer. No matter which one you choose, the important thing is to be tested.
If you’ve delayed your screening appointments or they have been postponed due to the COVID-19 pandemic, talk to your doctor about the steps you can take to safely resume these important tests.
The recommended tests fall into 2 categories:
Stool-based tests look at the stool (feces) for signs of cancer or pre-cancers. These tests are less invasive and easier to have done. But they usually need to be done more often than other types of tests.
- Fecal immunochemical test (FIT) is used to find tiny amounts of blood in the stool. This can be a sign of cancer or large polyps. You take this test at home with a kit you get from the doctor’s office. The FIT test needs to be done every year.
- Guaiac-based fecal occult blood test (gFOBT) is also used to find hidden blood in the stool. You take this test at home with a kit you get from the doctor’s office. The kit will include instructions on how to do the test and return it. If your doctor suggests a gFOBT test, you will may need to avoid some foods (such as red meat) and medicines (such as ibuprofen, aspirin and higher doses of Vitamin C) for several days before the test. The gFOBT test needs to be done every year.
- Stool DNA testing looks for certain DNA or gene changes in cells that can get into the stool from polyps (pre-cancerous growths) or cancer cells. It may also check for blood in the stool. For this test, people use a take-home kit to collect a stool sample and mail it to a lab. Cologuard® is the name of the stool DNA test that is currently FDA-approved. This stool test needs to be done every 3 years.
If any of these tests show abnormal signs of blood or DNA changes, a colonoscopy will need to be done to see if you have cancer. It’s important to remember that abnormal results do not necessarily mean that you have cancer because they can be caused by a non-cancerous condition, such as ulcers or hemorrhoids.
Stool-based tests are not the best option for everyone. They are recommended for people who have an average risk for colorectal cancer. If you have a personal history of polyps, colorectal cancer runs in your family, or you have other risk factors, your health care provider may suggest that you have a visual test.
Visual (or structural) tests look inside the colon and rectum for areas that might be cancer or polyps. These tests can be done less often than stool-based tests, but they require more preparation ahead of time, and can have some risks that stool-based tests don’t have.
- Colonoscopy uses a flexible lighted tube with a small camera on the end to look at the entire length of the colon and rectum. The tube is put in through the anus then into the rectum and colon. If polyps are found, they may be removed during the test. For a colonoscopy, your colon and rectum must be empty and clean so your doctor can see the entire lining during the test. You might hear this referred to as a “bowel prep.” There are different ways to do this, including pills, fluids, and enemas (or combinations of these). You will be given medicine to keep you relaxed and sleepy during the test (sedation) so will need a ride home after the test. If you are of average risk and nothing abnormal is found during the test, you won’t need another colonoscopy for 10 years.
- CT colonography (also called virtual colonoscopy) is a scan of the colon and rectum that provides detailed images of the colon and rectum so the doctor can look for polyps or cancer. It requires bowel prep, but no sedation. A small tube is put into your anus and air pumped into the rectum and colon before the scan. You’ll likely have 2 scans: one while you’re lying on your back and one while you’re on your stomach or side. If something is seen that may need to be biopsied, a follow-up colonoscopy will be needed. CT colonography must be done every 5 years.
- Flexible sigmoidoscopy is not widely used for colorectal cancer screening in the U.S. It’s like a colonoscopy but looks at less than half of the colon and rectum. Bowel prep is required before the test, but most people do not need sedation for this test. If polyps or suspicious areas are seen, a colonoscopy will be needed to look at the rest of the colon. Flexible sigmoidoscopy must be done every 5 years.
Talk to your doctor about screening
Regular screening is one of the most important ways to prevent colorectal cancer. If polyps are found during colorectal cancer testing, they can usually be removed before they turn into cancer. Screening can also help find cancer early, when it’s smaller and might be easier to treat. It’s important to get tested as often as recommended.
If you’re 45 or older, talk to your doctor about which screening test is right for you. Also check with your insurance company about coverage and what you might have to pay.
And no matter your age, talk to your doctor about your family medical history. People at higher risk for colorectal cancer because of family history or certain health conditions might need to start screening earlier than age 45 or be screened more often.