You may have seen the TV commercials about at-home colon cancer screening tests. If you’re nervous about getting a colonoscopy, you may be wondering if an at-home test is a better alternative, and if so, which one is best.
We talked to UNC Rex Digestive Healthcare gastroenterologist Silpa Yalamanchili, MD, to find out more. Here are three things we learned.
1. A colonoscopy is the best screening tool for colon cancer.
A colonoscopy can both detect and treat polyps (growths in the lining of the colon) before they turn into cancer. During a colonoscopy, a long, narrow, flexible tube with a high-definition camera at the end is used to evaluate a person’s rectum and colon. The procedure can take as little as 15 or 20 minutes.
Colonoscopies can detect conditions such as colitis, inflammatory bowel disease, bleeding and diverticulosis. But mainly, doctors are looking for precancerous or cancerous colon polyps, which are mushroom-shaped growths on the colon’s lining. If doctors spot polyps, they can quickly and painlessly remove them during the colonoscopy.
“There is up to a 70 percent reduction in colon cancer risk after colonoscopy,” Dr. Yalamanchili says.
2. A FIT kit is convenient but needs to be done yearly.
If you are unable to get a colonoscopy, a stool test such as a fecal immunochemical test (FIT kit) may be used. This test looks for early colorectal cancer in your stool and is completed annually at home.
“A FIT kit tests for hidden blood in your stool, which can be an early sign of cancer,” Dr. Yalamanchili says. “FIT kits detect blood from the lower intestines. It is not invasive and tends to be more accurate and have fewer false positive results than other stool-based tests.”
You do not need to do anything to prepare for a FIT test. You will need to collect a sample from your stool using a brush provided in your FIT kit. You then send the sample to a lab for review. A FIT kit is not recommended if you have a history of polyps.
There are some downsides to FIT kits, too.
“FIT tests are only able to detect cancers or advanced polyps after they develop, while a colonoscopy detects polyps before they grow into cancer,” Dr. Yalamanchili says.
In addition, FIT tests need to be done annually, whereas a colonoscopy can be done every 10 years if you are not considered high risk. Plus, if your FIT result is positive or abnormal, you will need a colonoscopy.
“If you have a positive FIT result, your insurance company may not cover the cost of a colonoscopy,” Dr. Yalamanchili says.
If you want to use a FIT kit, ask your doctor to order the test, which you will then pick up and drop off at a lab.
3. Cologuard is another colon cancer screening option—but has more false positives.
A Cologuard colon cancer test is an easy, at-home test that requires you to collect a full stool sample and mail the kit to the company. Your primary care physician orders the test, and a kit will be shipped to your home. You will collect a stool sample and mail it to a lab in a pre-addressed box. The lab will send results to your physician within two weeks. Insurance may cover some or all of the amount to use this test.
The company tests the DNA and blood cells in the sample to determine whether you have colon cancer or an advanced polyp.
“It does pick up cancers with a good sensitivity, just over 90 percent—if you’ve already got cancer or you’ve already got an advanced polyp,” Dr. Yalamanchili says. “If it’s positive, you need a colonoscopy to definitively diagnose a polyp or cancer.”
However, Cologuard can have false positive results (nearly 10 percent in some studies), meaning the test indicates you have cancer, but those findings are false. A colonoscopy is needed to reach a definitive diagnosis.
While Cologuard can detect cancer or an advanced polyp, its accuracy in detecting small polyps is not as good.
Colon cancer starts when a person develops a small polyp inside the colon. Over time, that polyp gets bigger. The larger it gets, the higher the risk it will turn into cancer. The way to prevent colon cancer is to detect and remove polyps in the colon before they become cancerous, and a colonoscopy is the only way to do that.
“The Cologuard is detection but not prevention,” Dr. Yalamanchili says. “Any screening test is better than nothing, but it is important to remember that not all screening tests are equal. The best test is a colonoscopy.”
If you have concerns about colon cancer, talk to your doctor. If you do not have a doctor, find one near you.