There are now more screening options than ever for detecting colorectal cancer, some from the comfort of one’s home. But for most people who are 50 years old or older — or younger but at higher risk — the colonoscopy is still the No. 1 recommended procedure.
Yes, it’s invasive and requires extensive prepping, but it is the most effective method available at catching potentially cancerous polyps early, or identifying actual cancerous changes — and removing them quickly and with minimal to no pain, say healthcare professionals.
“Many people are still confused about which test to take,” says Hanif Williams M.D. [1], a primary care physician with Baptist Health Primary Care [2] and chief of the Family Medicine department at Baptist Hospital, “but we know that the colonoscopy is still the gold standard. There is some inconvenience and some risks, but the procedure is safer than ever due to advanced technology.”
The three basic at-home screening kits available for colorectal cancers — the fecal occult blood test (FOBT); the fecal immunochemical test (FIT), and the stool DNA test (see more details below) — have to be repeated every 1 to 3 years, depending on the test chosen. Dr. Williams cautions that if there is a positive result in any of these home tests, the next most likely recommendation would be a colonoscopy.
Both the FOBT and the FIT are tests that look for blood in the gastrointestinal tract. But there can be false positives because blood in the G.I. tract can be the result of benign conditions, such as bleeding hemorrhoids. Also, some of these tests require dietary restrictions, but nothing as extensive as the “bowel prep” for a colonoscopy.
There is no single “ideal test” for any individual. Each home-based test has advantages and disadvantages, says Dr. Williams. He urges patients to talk to their primary care doctor about the pros and cons of each test, and at what age how often to be screened.
The U.S. Preventive Services Task Force recommends that adults age 50 to 75 be screened for colorectal cancer. You may need to start colorectal cancer screening before age 50, and possibly be screened more often, if you are considered at high risk. The following conditions may put you at a higher risk:
- Personal history of colorectal cancer or adenomatous polyps.
- Personal history of inflammatory bowel disease (ulcerative colitis or Crohn’s disease).
- A family history of colorectal cancer or polyps.
For everyone, the top risk factors for colorectal cancer are being overweight, smoking, heavy alcohol use, diets rich in red meat or overly processed meats, and a lack of exercise.
“Before a colonoscopy, I have a discussion with my patient, advising them of the risk factors for developing colon cancer, especially the importance of weight control, not smoking and following a proper diet,” says Dr. Williams. “I give the talk before the procedure because most people tend to return to bad habits afterward if everything turns out normal.”
Dr. Williams emphasizes that, unfortunately, about 1 in 3 people in the U.S. who should get tested for colorectal cancer have never been screened.
“In the early stages, there are usually no symptoms,” says Dr. Williams. “It’s important to be screened, one way or another. Don’t wait to be symptomatic. Tumors grow slowly. But if they are detected early, you can be cured.”
Here’s a summary of the top colorectal cancer screening options:
Colonoscopy
During a colonoscopy, the doctor looks at the full length of the colon and rectum with a colonoscope — a thin, flexible, lighted tube with a small video camera on the end. It is placed through the anus and into the rectum and colon. Instruments can be passed through the colonoscope to biopsy (sample) or remove any suspicious-looking areas such as polyps, if needed. Most patients are fully anesthetized so they don’t feel anything during a colonoscopy.
Some patients are semi-awake through “conscious sedation” – a combination of drugs to relax you and block pain. The afternoon or evening before the colonoscopy, drinking a liquid that will trigger bowel-clearing diarrhea is required. The exact colonoscopy prep instructions depend on the bowel prep your doctor prefers, the time of your colonoscopy and any prior experience you’ve had with colon preps. A colonoscopy is recommended every 10 years if the original one is normal and there are no other risk factors.
CT Colonography (Virtual Colonoscopy)
This test may be the best option for those who cannot or don’t want to go through an invasive test such as colonoscopy. The virtual option can be done fairly quickly, and sedation isn’t needed. But even though this test is not invasive, the same type of bowel prep that is required for the colonoscopy is also needed for this procedure. Also, a small, flexible tube is placed in the rectum to fill the colon with air. Another possible drawback is that if polyps or other suspicious areas are seen on this test, a colonoscopy will still probably be needed to remove them or to explore them fully. This would then be scheduled for another time and the bowel prep would have to be done again prior to the colonoscopy.
At-Home Testing Kits
Here are the three most common at-home screening options for colorectal cancer:
- The guaiac-based fecal occult blood test (gFOBT) uses the chemical guaiac to detect blood in the stool. For this test, which should be done annually, you receive a test kit from your primary care provider. At home, you use a stick or brush to obtain a small amount of stool. You return the test kit to the doctor or a lab, where the stool samples are examined for the presence of blood.
- The fecal immunochemical test (FIT) uses antibodies to detect blood in the stool. Some may find this test easier because there are no drug or dietary restrictions (vitamins and foods do not affect the FIT), and collecting the samples may be easier. This test is also less likely to detect bleeding from other parts of digestive tract, such as the stomach. It is also done once a year.
- The FIT-DNA test (also referred to as the stool DNA test) combines the FIT with a test that detects altered DNA in the stool. For this test, you collect an entire stool sample and send it to a lab to be checked for cancer cells. It is done once every three years.