A colonoscopy is the best screening test available for colorectal cancer. It is the only screening test that also prevents many colorectal cancers. Here are a few things you should know about this test:

• During a colonoscopy, your doctor examines the lining of your entire colon to check for polyps or tumors. If any polyps are found, they can be removed immediately.
• On the day of the colonoscopy, you will receive medication to help you relax. Most people fall asleep and do not remember much about the test when they wake up.
• Your doctor performs a colonoscopy by inserting a long, thin, flexible tube called a colonoscope into your colon through the rectum. The tube has a tiny video camera and light at the end that sends images to a video monitor.
• Before the procedure, you will receive instructions from your doctor on what to eat and how to empty your bowel.
• Both men and women should have a colonoscopy starting at age 50. People at increased risk of colorectal cancer may start earlier, depending on your doctor’s instructions. Also, your doctor will tell you in how many years you will need another colonoscopy.