Your best chance of surviving colorectal cancer is if your doctor finds and treats it early. The best way to find it early is with a regular screening test. Screening tests look for problems in people who don’t have symptoms. There aren’t routine screening tests for most cancers, but there are several tests that screen for colorectal cancer. Some of these tests also screen for abnormal growths called polyps, which might be found and removed before they have a chance to turn into cancer. Screening can be effective if your doctor finds polyps or cancer before you have symptoms. Then your doctor must follow up with a good treatment plan. These are the main screening tests for colorectal cancer:
Fecal occult blood test or fecal immunochemical test. These tests look for hidden blood in the stool. Hidden blood is called occult. Blood vessels in cancers or precancerous growths called polyps are easily broken during a bowel movement. This may cause blood to show up in the stool.
Flexible sigmoidoscopy. Your doctor uses this test to look at your rectum and lower colon, called the sigmoid colon. For the test, your doctor inserts a thin, lighted tube with a small video camera on the end into your rectum. The tube is called a sigmoidoscope. Your doctor may take tissue samples called biopsies of anything that looks unusual.
Colonoscopy. Your doctor uses this test to look at your rectum and your entire colon. It uses a long, lighted tube with a small video camera on the end called a colonoscope. The doctor inserts the scope into your rectum and through your colon. The doctor looks for growths called polyps, which can be removed. They are usually noncancerous or benign. Some polyps, though, can turn into cancer.
Barium enema. This test is also called a double contrast barium enema or an air contrast barium enema. A liquid called barium is put into the rectum with an enema. This chalky-white liquid coats the lower part of your intestine, making it easier to see during X-rays. Air is pumped in as well to expand the colon and rectum. Then a technician takes a series of X-rays to show any abnormalities in your colon and rectum.
Virtual colonoscopy (CT colonography). This test is a special type of CT scan of the colon and rectum. Once the CT images are taken, a computer is used to combine them to create a three-dimensional picture, which allows the doctor to look for polyps or cancer.
Colonoscopy is the only test that allows the doctor to view the entire colon and rectum and remove pieces of any abnormal areas for testing. If you have any of the other tests and something suspicious is found, you will likely need a colonoscopy.
Some of these tests may be uncomfortable and a little embarrassing. However, the sooner your doctor finds a polyp, the more likely it can be removed before it becomes cancer. Keep in mind, though, that screening doesn’t guarantee that you won’t get cancer. But if cancer is found at an early stage during screening, treatment is more likely to be effective.