Screening Methods for Colorectal Cancer
Screening methods for colorectal cancer, for people who do not have any symptoms or strong risk factors, include the following:
- Fecal occult blood test (FOBT). Checks for hidden (occult) blood in the stool. It involves placing a very small amount of stool on a special card, which is then sent to a laboratory.
- Fecal immunochemical test (FIT). A test that is similar to a FOBT, but does not require any restrictions on diet or medications prior to the test.
- Flexible sigmoidoscopy. A diagnostic procedure that allows the doctor to examine the inside of a portion of the large intestine. A short, flexible, lighted tube with a small video camera on the end, called a sigmoidoscope, is inserted into the intestine through the rectum. The scope blows air into the intestine to inflate it and make viewing the inside easier.
- Colonoscopy. A procedure that allows the doctor to view the entire length of the large intestine, and can often help identify abnormal growths, inflamed tissue, ulcers, and bleeding. It involves inserting a colonoscope, a long, flexible, lighted tube, in through the rectum up into the colon. The colonoscope allows the doctor to see the lining of the colon, remove tissue for further examination, and possibly treat some problems that are discovered.
- CT colonography (virtual colonoscopy). A procedure that uses computerized tomography (CT) scans to examine the colon for polyps or masses. The images are processed by a computer to make a three-dimensional (3-D) model of the colon. Virtual colonoscopy is noninvasive, although it requires a small tube to be inserted into the rectum to pump air into the colon. If something abnormal is seen with this test, a standard colonoscopy will be needed as follow up.
- Barium enema with air contrast (also called a double contrast barium enema). A fluid called barium (a metallic, chemical, chalky liquid used to coat the inside of organs so that they will show up on an X-ray) is administered into the rectum to partially fill up the colon. Air is then pumped in to expand the colon and rectum. An X-ray of the abdomen is then taken and can show strictures (narrowed areas), obstructions (blockages), and other problems.
Screening guidelines for colorectal cancer
Colorectal cancer screening guidelines from the American Cancer Society for early detection include:
- Beginning at age 50, both men and women should follow one of the examination schedules below:
- Fecal occult blood test or fecal immunochemical test every year
- Flexible sigmoidoscopy every five years
- Double-contrast barium enema every five years
- Colonoscopy every 10 years
- CT colonography (virtual colonoscopy) every five years
- People with any of the following colorectal cancer risk factors should begin screening procedures at an earlier age and/or be screened more often:
- Strong family history of colorectal cancer or polyps in a first-degree relative, especially in a parent or sibling before the age of 45 or in two first-degree relatives of any age
- Family with hereditary colorectal cancer syndromes, such as familial adenomatous polyposis and hereditary nonpolyposis colon cancer
- Personal history of colorectal cancer or adenomatous polyps
- Personal history of chronic inflammatory bowel disease (Crohn's disease or ulcerative colitis)