Colorectal cancer screening

Cancers of the colon and rectum (colorectal cancers) are some of the most preventable because screening tests can detect growths before they become cancerous, or find colorectal cancer early when treatment works best. Even so, colorectal cancer is the second leading cause of cancer deaths in the United States for men and women combined. A screening test is used to look for a disease when a person doesn’t have symptoms. Screening is vital to prevention of CRC and should be part of routine care for adults. And usually, there are no symptoms early on.

The gold standard for colorectal cancer screening is a colonoscopy. This test examines the entire colon looking for cancer, and your doctor can remove any polyps found during the test. There are other screening options, such as flexible sigmoidoscopy, double-contrast barium enema, virtual colonoscopy (CT colonography), fecal occult blood test (iFOBT), and DNA stool testing.

It’s recommended that all adults get their first colorectal cancer screening at age 50, or earlier if there’s a family history or medical condition that puts you at a higher risk. 90% of colorectal cancer happens to people after age 50. Your family MD can tell you if you are average or high risk. Early colorectal cancer often has no symptoms, so screening is essential for prevention/early detection. Colorectal cancer in later stages is much more difficult to treat.

Colonoscopy

During a colonoscopy, the entire length of your large intestine (colon) is examined. Polyps are detected and removed, and abnormal tissue can be biopsied.

What to expect

For the test to be effective, you have to empty your colon completely beforehand. For the day before, you’ll eat no food and drink only clear liquids. You’ll take a laxative (in liquid or pill form) and to clear the color of the stool. On the day of the test, you’ll be given sedation meds through a needle in your arm (IV) to relax you. While you’re lying on your side, your doctor inserts a long, flexible tube containing a camera through your anus and into your rectum and colon. This allows your doctor to see inside your colon. Any polyps can be removed using tools inserted through the tube. Your doctor can also collect tissue samples (biopsy) to check for cancer. The whole procedure takes about 30 minutes with recovery time of about an hour. Because you’ve been sedated, you won’t be able to drive or work that day, so you'll need to arrange for a ride home.

If any of the following screening tests detect abnormalities, your doctor may recommend you have a colonoscopy.

Flexible sigmoidoscopy

The flexible sigmoidoscopy test checks only the lower third of the colon, and it can detect polyps and cancer. It's recommended every five years.

What to expect

For the test to be effective, you have to empty your lower colon completely beforehand. For the day before, you’ll eat no food and drink only clear liquids. You’ll take a laxative (in liquid or pill form) or give yourself a small enema. On the day of the test, you won’t usually receive sedation meds. Your doctor inserts a thin tube (sigmoidoscope) containing a camera through your anus and into your rectum and lower colon. This allows your doctor to see inside your lower colon. If polyps are detected, they can be removed with tools inserted through the tube. Your doctor can also collect tissue samples (biopsy) to check for cancer. The whole procedure takes about 10 minutes, or longer if polyps are detected.

Double-contrast barium enema

The double-contrast barium enema test can detect large polyps and cancer and is recommended every five years.

What to expect

For the test to be effective, you have to empty your colon completely beforehand. For the day before, you’ll eat no food and drink only clear liquids. You’ll take a laxative (in liquid or pill form) to empty the colon. On the day of the test, you’ll have an enema with a barium solution and an injection of air through a tube inserted in your anus. The barium coats the lining of your intestines, which helps polyps and other abnormalities show up better on a series of X-rays taken of your rectum and colon. The test takes about 45 minutes.

Virtual colonoscopy (CT colonography)

This test can detect polyps and cancer and is recommended every five years.

What to expect

For the test to be effective, you have to empty your colon completely beforehand. For the day before, you’ll eat no food and drink only clear liquids. You’ll take a laxative (in liquid or pill form) to empty the colon. On the day of the test, you’ll lie on your side with your knees pulled toward your chest. Your doctor inserts a tube into your anus and puts air through it to make your colon easier to see. Then you’ll have CT (computed tomography) scans to produce pictures of your colon. You’ll lie on your back and your stomach so your doctor can get images from different angles. Scans are reviewed to check for abnormalities. The test takes about 30 minutes.

Immunochemical fecal occult blood test iFOBT

This test can help find cancer and is recommended once a year.

What to expect

This is a lab test that looks for hidden (occult) blood in your stool. No special preparation is needed. Your doctor gives you a kit and you provide a stool sample to your doctor or to a mail-in lab.

Stool DNA test

This test detects cancer, and there’s not yet a recommended amount of time between tests. It could be between two and five years.

What to expect

There’s no special preparation necessary. This is a new lab test that checks stool for DNA changes. Your doctor gives you a kit, and you provide a stool sample to your doctor or to a mail-in lab.