According to the American Cancer Society, everyone age 50 and over with an average risk of colorectal cancer should be screened in accordance with one of the following five testing schedules. People with a high risk of colorectal cancer should speak with their physician about earlier or more frequent screenings.
- Fecal occult blood test (FOBT) or fecal immunochemical test (FIT) every year. The FOBT uses a chemical reaction to detect the presence of blood in a stool sample. The sample is collected at home with a special kit and then sent to the doctor’s office or a medical laboratory for evaluation. An FIT is done in essentially the same way as an FOBT, but it detects only a specific portion of human blood protein and reduces the number of false positive results.
- Flexible sigmoidoscopy every five years. This is an examination of the lower third of the colon via a device called a sigmoidoscope, a small camera attached to a flexible tube, which is inserted through the rectum. A bowel preparation prior to the exam is necessary to clean out the lower colon.
- Annual FOBT or FIT and flexible sigmoidoscopy every five years.
- Double-contrast barium enema every five years. This is a procedure in which the colon is filled with barium sulfate and air, then x-rayed. The barium sulfate shows up on the x-ray and the air expands the colon, making it easier for the physician to see whether there are any abnormalities. Prior to the test, the intestines must be cleaned out using laxatives and a warm-water enema.
- Colonoscopy every 10 years. This examination of the colon uses a device called a colonoscope, a small camera on the end of a flexible tube, which is inserted through the rectum. Unlike a sigmoidoscopy, a colonscopy examines the entire colon. A clear-liquid diet and laxatives the day before the test and an enema the morning of the test are necessary to clean out the colon.
(See the Web site of the American Cancer Society for more information about colorectal cancer detection.)