Getting screened for colorectal cancer is crucial—colon cancer usually grows slowly and is often treatable when caught early. Colonoscopy is the leading test for identifying colorectal cancer. Travis Mason, MD, a surgical oncologist at Banner MD Anderson Cancer Center, calls it the “gold standard.” It’s recommended for people at average risk beginning at age 45.
Colonoscopies can identify 98% of cancers. And if your doctor discovers polyps during a colonoscopy, they can be biopsied during the same procedure. If you don’t have any polyps, you likely won’t need another colonoscopy for five to 10 years.
But there’s no getting around the fact that colonoscopies can be unpleasant. You need to clean out your colon and rectum ahead of time, so you’ll likely be on a liquid diet for a day before the procedure. And the night before, you’ll need to drink a liquid that induces diarrhea.
During the procedure, you’re sedated while your doctor inserts a long, flexible tube into your colon. Because of the sedation, you’ll need to have someone drive you home, though most people feel fine soon afterward.
You may be concerned about costs. Screening colonoscopies are covered by health insurance. But colonoscopies that are considered diagnostic, anesthesiologist’s fees, laxative drinks and out-of-network coverage can lead to unexpected bills.
Dr. Mason said that if you have a personal or family history of colon cancer or polyps, or a history of inflammatory bowel disease, a colonoscopy is your best choice. If you’re at average risk, you may want to consider some of these alternative screening tests.
Virtual colonoscopy
Virtual colonoscopy, also called a screening CT colonoscopy, uses a CT scan to create images of your internal organs.
- How it compares to colonoscopy: Virtual colonoscopy can identify 94% of polyps that are eight to 10 millimeters or larger and 88% of polyps six millimeters or less. As with a colonoscopy, you will likely need to drink clear liquids and take a laxative the day before your exam, so your colon is empty.
- Advantages: There’s no risk of bleeding or perforation and patients usually do not require sedation.
- Disadvantages: Virtual colonoscopy is less sensitive for detecting small polyps, and with it, you’re unable to sample any abnormal tissue. Your colon needs to be inflated with gas to get clear images, which can be uncomfortable. And it may not be covered by insurance.
- Who can qualify: You may qualify if you are at average risk of colon cancer, are at risk of bleeding from a colonoscopy due to a blood clotting disorder, have a bowel obstruction, can’t be sedated or are reluctant to have a full colonoscopy. You’re likely not a candidate if you have a personal or family history of colon cancer or colon polyps, inflammatory bowel disease or a history of diverticulitis.
- How often it’s typically repeated: Every five years.
Fecal immunochemical test (FIT)
FIT uses antibodies to detect blood in the stool. For this test, you collect a stool sample and mail it to a lab or return it to your doctor.
- How it compares to colonoscopy: FIT detects cancer about 70 % of the time.
- Advantages: You can collect samples at home, and you don’t need to be sedated or take laxatives. FIT tests generally cost $20 or less and may be covered by your health insurance plan.
- Disadvantages: This test doesn’t find as many cancers or polyps as colonoscopies, and if you get a positive result, you may need additional testing.
- Who can qualify: Most people at average risk of colon cancer who may have reasons to avoid a colonoscopy.
- How often it’s typically repeated: Every year.
A similar test, called an immunochemical fecal occult blood test (iFOBT), uses an enzyme to detect hemoglobin in the blood. However, these tests are not recommended. “Most screening recommendations encourage phasing out iFOBT because of its low sensitivity,” Dr. Mason said.
Stool DNA tests
Stool DNA tests, like Cologuard, look for DNA in your stool that might indicate polyps or colon cancer. As with FIT tests, you collect a stool sample at home and mail it in for evaluation.
- How it compares to colonoscopy: The test can pick up 92% of cancers and 42% of polyps.
- Advantages: You don’t need to take laxatives to empty your bowel.
- Disadvantages: It is less sensitive than colonoscopy at detecting polyps.
- Who can qualify: Most people at average risk of colon cancer who may have reasons to avoid a colonoscopy.
- How often it’s typically repeated: Every three years.
Flexible sigmoidoscopy
In this procedure, medical professionals use a narrow, flexible scope to look inside your rectum and colon. It’s not used that often because it’s similar to a colonoscopy and a colonoscopy gets better results.
- How it compares to colonoscopy: This test detects 63 to 80% of cancers, depending on race and gender. By combining it with FIT, it may be able to detect more than 90% of cancers.
- Advantages: You might be able to have flexible sigmoidoscopy without being sedated.
- Disadvantages: You need to take laxatives to empty your bowel. You will need a colonoscopy if your test shows signs of cancer or polyps.
- Who can qualify: Flexible sigmoidoscopy plus FIT is generally used for people who don’t have access to colonoscopy or virtual colonoscopy or people who can’t tolerate sedation.
- How often it’s typically repeated: Every five years.
The bottom line
If you’re age 45 or older, or younger and at higher risk, it’s crucial to be screened for colon cancer. Colonoscopy is the gold standard, but there are other options to consider if a colonoscopy might not work for you. To learn more about your options for colon cancer screening, connect with a Banner health care provider near you.
