Screening Tests: What Do They Entail?
| Screening Recommendations
| What Tests Do You Need?
Just talking about a
makes most people cringe. That is probably because the idea of having a tube inserted into your rectum and colon is disturbing.
The thought of getting colorectal cancer is even more disturbing. But, the chances of survival are high when diagnosed before the cancer has invaded the colon wall or spread.
What about colorectal screening? Is the unpleasant prospect of having a colonoscopy or some other equally disagreeable procedure really worth it? For many of us, the answer is “yes.”
Screening Tests: What Do They Entail?
Colorectal screening tests are designed to detect cancer or finger-like projections of tissue called
polyps. Polyps may be cancerous or precancerous. Although most polyps are not cancerous, the vast majority of colorectal cancers are believed to begin as polyps. Here is what is involved with each screening test to detect polyps and colorectal cancer:
fecal occult blood test and fecal immunochemical test
look for hidden blood in a sample of stool (feces) you have already passed. Blood in your feces may be the result of bleeding from a cancerous polyp in your colon or rectum, or it may be a sign of a more benign condition.
flexible sigmoidoscopy, a thin, lighted tube with a camara on the end is inserted into the rectum and lower colon to examine their internal mucosal lining. Images can be recorded while the doctor looks for polyps and other abnormalities on a monitor. This procedure does not look at the entire length of the colon like a colonoscopy does.
colonoscopy, a thin tube similar to a flexible sigmoidoscope is used. This time, the lighted tube goes all the way through to the end of your colon where it connects to the small intestine. Polyps that are detected can be removed during the procedure.
double-contrast barium enema
injection of a fluid called barium followed by air into your rectum. This makes your entire colon visible on an x-ray, allowing doctors to see abnormal growths, like polyps.
Computed tomography colography (“virtual colonoscopy”) is a technique that takes computer generated x-ray images after injection of air into the colon. One disadvantage to having this test compared to a colonoscopy is if a polyp is discovered during colonoscopy it can be removed right then and there, while if one is detected with virtual colonoscopy, a follow-up colonoscopy will be necessary.
The American Cancer Society suggests that starting at age 50, men and women at average risk of developing colorectal cancer should use one of the following options:
- Flexible sigmoidoscopy every 5 years; or
- Double-contrast barium enema every 5 years; or
- CT colonography (virtual colonoscopy) every 5 years; or
- Colonoscopy every 10 years; or
- Yearly fecal occult blood test; or
- Yearly fecal immunochemical test every year; or
However, people at increased risk of colorectal cancer may need to have some of these tests earlier in life and more often. Some reasons why you would be considered high risk are:
- Personal or family history of colorectal cancer or adenomatous polyps
Personal history of chronic inflammatory bowel disease, such as
What Tests Do You Need?
Talk to your doctor about the advantages and disadvantages of each screening test, especially if your risk for colorectal cancer is greater than average. These tests may save your life.
Colon and rectal cancer.
National Cancer Institute website. Available at
http://www.cancer.gov/cancertopics/types/colon-and-rectal. Accessed July 11, 2012.
Colorectal cancer early detection. American Cancer Society website. Available at
http://www.cancer.org/Cancer/ColonandRectumCancer/MoreInformation/ColonandRectumCancerEarlyDetection/colorectal-cancer-early-detection-acs-recommendations. Updated June 15, 2012. Accessed July 11, 2012.
Colorectal cancer prevention and treatment.
American Gastrenterological Association website. Available at
http://www.gastro.org/patient-center/digestive-conditions/colorectal-cancer. Accessed July 11, 2012.
Colorectal cancer screening tests. American Cancer Society website. Available at: http://www.cancer.org/Cancer/ColonandRectumCancer/MoreInformation/ColonandRectumCancerEarlyDetection/colorectal-cancer-early-detection-screening-tests-usedUpdated June 15, 2012. Accessed July 11, 2012.
Colorectal (colon) cancer.
Centers for Disease Control and Prevention website. Available at
http://www.cdc.gov/cancer/colorectal/. Updated June 20, 2012. Accessed July 11, 2012.
Levin B, Lieberman DA, McFarland B, et al. Screening and surveillance for the early detection for colorectal cancer and adenomatous polyps, 2008: a joint guideline from the American cancer society, the US multi-society task force on colorectal cancer, and the American college of radiology.
Gastroenterology. 2008 Feb 8.
Screening for colorectal cancer. United States Preventive Services Task Force website. Available at
http://www.uspreventiveservicestaskforce.org/uspstf/uspscolo.htm. Updated March 2009. Accessed July 11, 2012.
Last reviewed July 2011 by Brian Randall, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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