Colorectal Cancer Screening

Colonoscopy

Colorectal cancers are some of the most preventable cancers because screening tests can detect growths before they become cancerous.

Most colorectal cancers develop from polyps (growths on the lining of the colon). Polyps are usually noncancerous when they first appear. Over time, they can turn into cancerous polyps (adenoma). Removal of these polyps can reduce your risk of colon cancer by more than 80 percent.

Colon cancer most commonly occurs in the lower part of the colon. Cancer in the rectum is called rectal cancer. Together, they are referred to as colorectal cancer.

Colonoscopy is the only colorectal screening test that examines the entire colon and can remove any polyps found during the test. There are other colorectal cancer screening tools, but colonoscopy is the gold standard.

When to Get Screened

Adults should have colorectal screenings beginning at age 50. If you have a family history of colorectal cancer or a medical condition that puts you at high risk, your doctor might suggest earlier screening.

Screening Options

Colonsocopy

  • Checks entire length of large intestine and colon
  • Detects polyps and cancer and removes polyps
  • Frequency: Every 10 years for most people
  • Preparation: Your colon must be empty for the test to be effective. Your doctor explains how to prepare for the exam. You follow a specific diet the day before  - no food and only clear liquids. You take a liquid or pill laxative and, sometimes, give yourself an enema.
  • What to expect: You are given sedation medication through an IV (needle in your arm) to relax you. You lie on your side, and 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 large intestine and colon on monitors. If polyps are detected, they can be removed with tools inserted through the tube. If a biopsy is needed to check for cancer, these tissue samples can be collected during the colonoscopy. A colonoscopy takes about 30 minutes. Bring someone to drive you home because you’ve had sedation medication.

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

Flexible Sigmoidoscopy

  • Checks only the lower one-third of the colon; detects polyps and cancer
  • Frequency: Every five years
  • Preparation: Your colon must be empty for the test to be effective. Your doctor explains how to prepare for the exam. You follow a specific diet the day before - no food and only clear liquids. You take a liquid or pill laxative and, sometimes, give yourself an enema.
  • What to expect: You don’t usually have sedation medication. Your doctor inserts a long 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 on monitors. If polyps are detected, they can be removed with tools inserted through the tube. If a biopsy is needed to check for cancer, these tissue samples can be collected during the colonoscopy. This exam usually takes about 15 minutes unless polyps are detected.

Double-contrast Barium Enema

  • Detects large polyps and cancer
  • Frequency: Every five years
  • Preparation: Your colon must be empty for the test to be effective. Your doctor explains how to prepare for the exam. You follow a specific diet the day before - no food and only clear liquids. You take a liquid or pill laxative and, sometimes, give yourself an enema.
  • What to expect: This test involves a series of X-rays of your colon and rectum. At the clinic or hospital, you 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 to help polyps and other abnormalities show up better on X-rays.

Virtual Colonoscopy (CT Colonography)

  • Detects polyps and cancer
  • Frequency: Every five years
  • Preparation: Your colon must be empty for the test to be effective. Your doctor explains how to prepare for the exam. You follow a specific diet the day before  - no food and only clear liquids. You take a liquid or pill laxative and, sometimes, give yourself an enema.
  • What to expect: You have CT (computed tomography) scans to produce pictures of your colon. Your doctor views the scans to look for abnormalities. This test might be right for you if you can’t have colonoscopy. You lie on your side with your knees pulled toward your chest. Your doctor inserts a tube into your anus and pumps air through it to make your colon easier to see. Then you lie on your back and your stomach to get images from different angles.

Fecal Occult Blood Test (FOBT)

  • Detects cancer
  • Frequency: Yearly
  • Preparation: Your doctor provides instructions about foods to avoid for a few days before the test.
  • What to expect: This is a lab test to check for hidden (occult) blood in your stool. There are several types of tests and kits. You may provide stool samples over one or several bowel movements to your doctor or to a mail-in laboratory.

Stool DNA Test

  • Detects cancer
  • Frequency: not yet determined; possibly every two to five years
  • Preparation: No special preparation required
  • What to expect: This is a new lab test that checks stool for changes in your DNA. Your doctor gives you a kit. You provide a stool sample to your doctor or to a mail-in laboratory.

Find an Aurora Health Care GI Specialist