It's common knowledge that finding and treating cancer early can save your life. Many cancers grow slowly over a period of years, without presenting symptoms until it's too late. Fortunately, you can stay one step ahead by getting recommended screening tests. Screening tests are used to detect cancer in specific areas of the body before symptoms appear. If cancer is found during a screening test, prompt treatment may increase your chance of a cure and prolong your life.
Colorectal cancer encompasses the colon and rectum. They are third leading cause of cancer deaths in the United States. The chances of survival are high when diagnosed before the cancer invades adjacent tissue or spreads to another site. Screening has become very important in the battle against these types of cancer.
The thought of a colonoscopy can be unnerving, but in reality it is a short, painless procedure. However, you do have other options. There are many different colorectal screening tests to choose from.
Colorectal screening tests are designed to detect cancer or polyps. Polyps are finger-like projections that grow on the inside of the colon wall. Generally, polyps are not cancerous, but the it is believed the vast majority of colorectal cancers begin as polyps. Polyps can also be found to be precancerous. Precancerous polyps have subtle changes associated with them that increase the risk of them becoming cancerous over time.
The risk of colorectal cancer increases with age. For men with average risk, this means screening should begin at age 50 (age 45 for African Americans, American Indians/Alaska Natives). The time between tests depends on the type of test you choose to have and your underlying risk. Recommended screening tests include the following:
The 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.
For a 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. Polyps or other abnormal tissue can be removed during the procedure and examined under a microscope.
For a 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 or other abnormal tissue can be removed during the procedure and examined under a microscope.
A double-contrast barium enema involves the injection of contrast material 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.
CT colonography 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. Another is the amount of radiation exposure to do the test.
An MR colonography uses magnetic fields to view the entire colon. Water and contrast material are used to expand and view the colon. Compared to conventional colonoscopy, MR colonongraphy is not as effective at detecting smaller polyps. Again, if polyps are detected, a follow-up colonoscopy will be necessary. There is no radiation exposure.
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:
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:
When you receive the results of your screening test, your doctor will advise you when you should have another test. Depending on the result, it may be more often than the recommended time frames outlined above.
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.
American Cancer Society
National Cancer Institute
Canadian Cancer Society
Colon Cancer Canada
American Cancer Society recommendations for 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 February 1, 2016. Accessed March 23, 2016.
Colorectal cancer. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated February 15, 2016. Accessed March 23, 2016.
Colorectal cancer: Screening. United States Preventive Services Task Force website. Available at http://www.uspreventiveservicestaskforce.org/Page/Document/UpdateSummaryFinal/colorectal-cancer-screening. Updated October 2008. Accessed March 23, 2016.
Colorectal cancer screening. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated December 11, 2015. Accessed March 23, 2016.
Colorectal cancer screening—patient version. National Cancer Institute website. Available at http://www.cancer.gov/types/colorectal/patient/colorectal-screening-pdq. Update June 6, 2013. Accessed March 23, 2016.
Colorectal cancer screening tests. American Cancer Society website. Available at: http://www.cancer.org/Cancer/ColonandRectumCancer/MoreInformation/ColonandRectumCancerEarlyDetection/colorectal-cancer-early-detection-screening-tests-used. Updated February 1, 2016. Accessed March 23, 2016.
Colorectal (colon) cancer. Centers for Disease Control and Prevention website. Available at http://www.cdc.gov/cancer/colorectal. Updated March 15, 2016. Accessed March 23, 2016.
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;134(5):1570-1595.
4/8/2014 DynaMed's Systematic Literature Surveillance. http://www.ebscohost.com/dynamed: Yee J, Kim DH, et al. Colorectal cancer screening. American College of Radiology (ACR) Appropriateness Criteria. Available at: http://www.acr.org/~/media/ACR/Documents/AppCriteria/Diagnostic/ColorectalCancerScreening.pdf. Updated 2013. Accessed March 23, 2016.
Last reviewed March 2016 by Michael Woods, 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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