You Wanted to Know: Colon Cancer Screening Options

Rare Diseases Are Hard to Overcome

Though none of the screening options to detect colon cancer are particularly fun, they are some of the most important and scientifically proven things you can do to safeguard yourself from this second-leading cause of cancer-related death. There are several different options for colon cancer screening, including colonoscopy, flexible sigmoidoscopy and fecal occult blood tests (FOBTs). One of our viewers asked me on Twitter about the best way to choose between these screening tests.


The U.S. Preventative Services Task Force (USPSTF), a highly respected panel that sets general guidelines for health screenings, recommends one of three different screening regimens. They are:

Colonoscopy: This allows for the most-thorough look at the colon and is the gold-standard test for colon cancer. During a colonoscopy, a trained physician uses a long flexible tube with a camera on the end of it to directly examine the walls of the colon for polyps, which may be cancerous or pre-cancerous. During the procedure, which usually takes about 30 minutes and is done under light sedation, the physician can also remove any polyps, effectively treating or preventing cancer growth. People at average risk for colon cancer should have a colonoscopy every 10 years starting at age 50 and stopping at age 75. Certain people with a personal or family history of colon cancer or with a high-risk condition like ulcerative colitis may require earlier or more frequent screening. You can learn more about who should get a colonoscopy and what to expect here.

Flexible sigmoidoscopy: During this exam, a doctor uses a thin, flexible lighted tube with a camera on the end to look just at the lower part of the colon. Usually, the doctor can get a good look at the rectum, but can only see less than half of the colon. This procedure usually takes about 10 to 20 minutes and does not require sedation (though patients may choose it).  The USPSTF recommends that patients who opt for a sigmoidoscopy instead of a colonoscopy get screened once every five years starting at age 50 until age 75, with an additional sensitive fecal occult blood test every three years.

Fecal occult blood tests: FOBTs are lab tests done at home, which use stool smeared onto small strips of paper to detect the presence of blood in the stool. Blood in the stool may be a sign of colon cancer, since polyps can become irritated and bleed in small amounts that can only be detected using special chemicals. However, not all polyps bleed and certain other medical conditions like hemorrhoids, diverticulosis or anal fissures may also cause bleeding. A positive FOBT, therefore, doesn’t necessarily mean you have cancer, and a negative FOBT doesn’t mean that you absolutely don’t. Certain foods or medications may also make a false positive test more likely. A positive test usually requires follow up with another screening test like a colonoscopy. If you choose to screen with FOBTs, you should make sure that you test three consecutive stool samples (from three separate bowel movements). This test should be repeated every year between ages 50 and 75.

Several improved and new screening tests are currently under development, including more accurate and sensitive FOBTs and other fecal analyses that can detect signs of cancer. One of these is the immunochemical fecal occult blood test, in which patients usually submit a stool sample to your doctor or lab for special testing. This is more sensitive than a regular FOBT but is not yet as commonly used.

All of these screening methods are reasonable options and are thought to produce similar results when it comes to preventing colon cancer deaths. However, for the time being, colonoscopy is the best, most-thorough screening test for colon cancer. However, each patient’s situation and medical background varies, and it’s always best to make the decision of which screening test is right for you along with your doctor. Never hesitate to ask for more information about the best methods of colon cancer screening – it could save your life.