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continued:

Colon cancer screening: Weighing the options

What is your doctor's approach to screening tests?

Make sure that you're comfortable with the colon cancer screening test your doctor recommends. If your doctor specializes in a particular test but you'd rather have another test, express your wishes. If necessary, your doctor may offer a referral to someone trained in the test with which you feel most comfortable.

What is your risk level?

Your risk of colon cancer may influence your choice of screening tests. For example, your doctor may recommend colonoscopy as the screening tool of choice, likely at frequent intervals, if you:

  • Have a personal history of colon cancer or precancerous polyps
  • Have a parent, sibling or child who's had colon cancer
  • Carry a gene for a hereditary colon cancer syndrome
  • Have a history of inflammatory bowel disease, such as ulcerative colitis or Crohn's disease

What are the pros and cons of each test?

Here's an overview of the most common colon cancer screening tests.

Colonoscopy
A colonoscopy is an exam used to detect changes or abnormalities in the large intestine and rectum. A long, flexible tube (colonoscope) is inserted into the rectum. A tiny video camera at the tip of the tube allows the doctor to view the inside of the entire colon.

  • Pros: Colonoscopy is considered the gold standard for colon cancer screening. Polyps or other types of abnormal tissue can be removed through the scope during the exam. Tissue samples (biopsies) can be taken as well. The exam takes 20 minutes to an hour.
  • Cons: The test may not detect all small polyps and cancers. You may need to adjust your usual medications before the exam. Solid food can't be eaten the day before the exam. Emptying the colon with laxatives, enemas or both can be unpleasant. Sedation is recommended. Rare complications may include an adverse reaction to the sedative, bleeding from the site where a biopsy was taken or a polyp or other abnormal tissue was removed, or a tear in the colon or rectum wall. It may take a day for the sedative to wear off. Bloating may occur for a few hours after the exam.

Virtual colonoscopy
A virtual colonoscopy (computerized tomography colonography) is an exam used to detect changes or abnormalities in the large intestine and rectum. A catheter is placed inside the rectum to fill the colon with air or carbon dioxide. Computerized tomography (CT) is used to produce cross-sectional images of the abdominal organs.

  • Pros: Unlike traditional colonoscopy, virtual colonoscopy doesn't require sedation or the insertion of a scope into the colon. The exam takes about 10 minutes.
  • Cons: The test may not detect all small polyps and cancers. You may need to adjust your usual medications before the exam. Solid food can't be eaten the day before the exam. Emptying the colon with laxatives, enemas or both can be unpleasant. An adverse reaction to the contrast agent sometimes used during virtual colonoscopy is possible. Radiation exposure may be a concern. Biopsies can't be performed during the procedure. If an abnormality is detected, a colonoscopy may be necessary. Bloating may occur for a few hours after the exam. Many doctors consider virtual colonoscopy experimental.

Fecal occult blood test
A fecal occult blood test is a lab test used to check stool samples for hidden (occult) blood.

  • Pros: Stool sample collection can be done at home. There's no need to empty the colon ahead of time.
  • Cons: The test fails to detect most polyps and some cancers. Certain foods and medications must be avoided for three days before the test. If blood is detected, additional tests may be needed to determine the source. False-negative and false-positive results are possible.

Flexible sigmoidoscopy
A flexible sigmoidoscopy is an exam used to evaluate the lower part of the colon. A thin, flexible tube (sigmoidoscope) is inserted into the rectum. A tiny video camera at the tip of the tube allows the doctor to view the inside of the rectum and most of the sigmoid colon.

  • Pros: Sedation isn't required. Biopsies can be taken through the scope during the exam. The exam takes about 15 minutes.
  • Cons: You may need to adjust your usual medications before the exam. Solid food can't be eaten the day before the exam. Emptying the colon with laxatives, enemas or both can be unpleasant. The exam doesn't allow the doctor to see the entire colon. Rare complications may include bleeding from the biopsy site or a tear in the lining of the colon. Bloating may occur for a few hours after the exam. Additional tests may be necessary if an abnormality is detected.

DNA stool test
A DNA stool test screens stool for DNA mutations, indicating the presence of precancerous polyps or colon cancer.

  • Pros: No dietary changes are required before the test. There's no need to empty the colon ahead of time. Stool sample collection can be done at home.
  • Cons: The test currently screens for a limited number of DNA mutations in stool. The test hasn't been universally accepted as a screening tool for colon cancer. False-negative results are possible.

Barium enema
A barium enema is a special X-ray used to detect changes or abnormalities in the large intestine (colon). A lubricated enema tube is inserted into the rectum to deliver liquid barium and sometimes air into the colon. This provides a clear silhouette of the inner lining of the colon on X-ray images.

  • Pros: Sedation isn't required. The exam takes 20 to 40 minutes.
  • Cons: The test may not detect some small polyps and cancers. You may need to adjust your usual medications before the exam. Solid food can't be eaten the day before the exam. Emptying the colon with laxatives, suppositories or both can be unpleasant. Rare complications may include inflammation in the tissues surrounding the colon, obstruction in the gastrointestinal tract and tears in the colon wall. Barium may cause constipation.

What's the bottom line?

Choosing a colon cancer screening test isn't always an easy decision, but it's a potentially lifesaving one. Consult your doctor about your colon cancer screening options. Whatever your choice, remember that some screening is better than no screening.

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