Colon-Cancer Screenings: Weighing the Options

By Jane Farrell

Editor’s note: If you ever thought getting a colonoscopy was the only way to screen for colon cancer, you’re wrong. Here, the experts from the Mayo Clinic explain what the choices are:
WHAT IS YOUR DOCTOR’S APPROACH TO COLON-CANCER SCREENING?

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 might 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 might influence your choice of screening tests. For example, your doctor might 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 generally 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 typically takes about 30 to 60 minutes.

Cons. The exam might not detect all small polyps and cancers. You might need to adjust your usual medications before the exam. Typically, you can’t eat solid food the day before the exam and you’ll need to use laxatives or another product to empty your colon. Sedation is generally recommended. Rare complications may include 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. Cramping or bloating might occur after the exam. Since the sedative can take hours to wear off, you’ll need to arrange for someone to drive you home.

CT colonography (virtual colonoscopy)

CT colonography, also known as virtual colonoscopy, is an exam used to detect changes or abnormalities in the large intestine and rectum. During this exam, an imaging technique known as computerized tomography (CT) is used to produce cross-sectional images of the abdominal organs. To help create clear images, a small tube (catheter) is placed inside your rectum to fill your colon with air or carbon dioxide.

Pros. Unlike traditional colonoscopy, CT colonography doesn’t require sedation or the insertion of a scope into the colon. The exam typically takes about 10 minutes.

Cons. The exam might not detect all small polyps and cancers. You might need to adjust your usual medications before the exam. Typically, you can’t eat solid food the day before the exam. You might need to use laxatives or another product to empty your colon. Radiation exposure from repeated procedures might be a concern. Since tissue samples can’t be taken during the exam, a follow-up colonoscopy might be needed if an abnormality is detected. Cramping or bloating might occur after the exam.

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 might need to be avoided for several days before the test. If blood is detected, additional tests might be needed to determine the source. False-negative and false-positive results are possible.

Flexible sigmoidoscopy

Flexible sigmoidoscopy is an exam used to evaluate the lower part of the colon (sigmoid 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 usually needed. Biopsies can be taken through the scope during the exam. The exam typically takes about 15 to 20 minutes.

Cons. Typically one or more enemas are done before the procedure to empty the lower part of the colon. In some cases, you might not be able to eat solid food the day before the exam. The exam doesn’t allow the doctor to see the entire colon, so any cancers or polyps farther into the colon can’t be detected. Rare complications may include bleeding from the biopsy site or a tear in the lining of the colon. Cramping or bloating might occur after the exam. Additional tests might be necessary if an abnormality is detected.

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. Commit to a screening schedule based on your personal risk factors. Remember, the earlier colon cancer is detected, the easier it is to treat.

Reprinted with permission of Mayo Clinic.