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 U.S. for men and women combined.

What is a colorectal cancer screening?

A colorectal cancer screening is used to look for a disease when a person doesn’t have symptoms. Screening is vital to cancer prevention 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.

What are the recommended screening guidelines for colorectal cancers?

It’s recommended that all adults get their first colorectal cancer screening at age 45, or earlier if there’s a family history or medical condition that puts you at a higher risk. Ninety percent of colorectal cancer happens to people after age 50. Your doctor can tell you if you are average or high risk. Early colorectal cancer often has no symptoms, so screening is essential for prevention and early detection. Colorectal cancer in later stages is much more difficult to treat.

What are some of the benefits or limits of colorectal cancer screening tests?

Colorectal cancer screening tests reduce mortality rates by supporting preventive care. While there may be some risk of complications from invasive procedures, screening tests can detect cancer when it is most treatable. This helps doctors address polyps early to prevent the development of cancer.

What is a 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.

How to prepare for a colonoscopy

For the screening to be effective, you have to empty your colon completely beforehand. The day before, you’ll eat no food and drink only clear liquids. You’ll take a laxative (in liquid or pill form) to clear the color of the stool.

What happens during a colonoscopy?

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.

What is a flexible sigmoidoscopy?

A flexible sigmoidoscopy test checks only the lower third of the colon and can detect polyps and cancer. A flexible sigmoidoscopy is recommended every five years for people with an average risk for colorectal cancer. People with an elevated risk should receive this exam more frequently, as determined by a doctor.

How to prep for a flexible sigmoidoscopy

For the screening 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.

What happens during a flexible sigmoidoscopy?

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.

What is a double-contrast barium enema?

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

How to make preparation for a double-contrast barium enema

For the screening 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.

What happens during a double-contrast barium enema?

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.

What is a virtual colonoscopy or CT colonography?

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

How to prepare for a virtual colonoscopy

For the screening 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.

What happens during a virtual colonoscopy?

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.

What is an immunochemical fecal occult blood test (iFOBT)?

An immunochemical fecal occult blood test can help find cancer. It is recommended you receive an iFOBT once a year, or every other year depending on your risk factors.

How to prep for a virtual colonoscopy

This is a lab-based screening 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.

What is a stool DNA test?

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

How to make preparation for a stool DNA test

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.