Screening for colon cancer; Colonoscopy – screening; Sigmoidoscopy – screening; Virtual colonoscopy – screening
There are several ways to screen for colon cancer.
Polyps in the colon and smaller cancers can cause small amounts of bleeding that cannot be seen with the naked eye. But the blood can often be found in the stool.
This method checks your stool for blood.
The most common test used is the
fecal occult blood test(FOBT). Two other tests are called the fecal immunochemical test (FIT) and stool DNA test (sDNA).
This test uses a flexible small scope to view the lower part of your colon. Because the test only looks at the last one-third of the large intestine (colon), it may miss some cancers that are higher in the large intestine.
Sigmoidoscopy and a stool test should be used together.
- A colonoscopy is similar to a sigmoidoscopy, but the entire colon can be viewed.
- During a colonoscopy, you receive medicine to make you relaxed and sleepy.
- Sometimes, CT scans are used as an alternative to a regular colonoscopy. This is called a
Double-contrast barium enema is a special x-ray of the large intestine that looks at the colon and rectum
Capsule endoscopy involves swallowing a small, pill-sized camera. The method is being studied, so it is not recommended for standard screening at this time.
SCREENING FOR AVERAGE-RISK PEOPLE
There is not enough evidence to say which screening method is best. Talk to your doctor about which test is right for you.
Both men and women should have a colon cancer screening test starting at age 50. Some health care providers recommend that African Americans begin screening at age 45.
Screening options for patients with an average risk for colon cancer:
Colonoscopy every 10 years
Double-contrast barium enemaevery 5 years
Fecal occult blood test (FOBT) every year (colonoscopy is needed if results are positive)
sigmoidoscopyevery 5 to 10 years, usually with stool testing FOBT done every 1 to 3 years
- Virtual colonoscopy every 5 years
SCREENING FOR HIGHER-RISK PEOPLE
People with certain risk factors for colon cancer may need earlier (before age 50) or more frequent testing.
More common risk factors are:
- A family history of inherited colorectal cancer syndromes, such as familial adenomatous polyposis (FAP) or hereditary nonpolyposis colorectal cancer (HNPCC)
- A strong family history of colorectal cancer or polyps. This usually means first-degree relatives (parent, sibling, or child) who developed these conditions younger than age 60.
- A personal history of colorectal cancer or polyps
- A personal history of chronic inflammatory bowel disease (for example,
ulcerative colitisor Crohn disease)
Screening for these groups is more likely to be done using colonoscopy.
Related:Ulcerative colitis – discharge, Virtual colonoscopy