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The Test That Could Save Your Life

Traditional or virtual colonoscopy screenings can help your doctor detect colon cancer in its early stages

A happy middle aged man and woman embrace on a beach.

by David Roseman, Gastroenterologist

It’s one of those cancers that no one likes to talk about and, even when they do, the conversations are too often riddled misconceptions such as “Only men get it” or “It’s always fatal.”

The truth is, colon cancer affects both men and women equally and, when detected in its earliest stages, it’s one of the most preventable forms of cancer.

While it does take the lives of some 60,000 Americans every year, that number could potentially be cut in half if everyone age 50 and older simply got tested.

Colon cancer is usually preceded by changes in the tissue lining the colon (also known as the bowel or large intestine) or rectum. Often, these changes take the form of small growths or polyps. Testing for and removing polyps and other types of abnormal tissue may prevent them from becoming cancerous.

Moreover, even if cancer is already present, the chances of successfully treating it are much better if detected early. In fact, the five-year survival rate for patients whose colon cancer is detected in the early stages is 90 percent.

Testing for colon cancer

The average man or woman has about a 5 percent chance of developing colon cancer during their lifetime. More than 90 percent of people diagnosed with colon cancer are 50 or over, and African-Americans have a slightly higher risk than other racial or ethnic groups. Other risk factors include:

  • Personal history of polyps or chronic inflammatory bowel disease (such as ulcerative colitis or Crohn’s disease).
  • Family history of colon cancer or colon polyps
  • An inherited condition that may increase risk
  • Smoking or use of other tobacco products
  • A diet that is high in fat, especially animal fat, and low in fiber
  • Obesity

Because colon cancer usually has no symptoms early on, the only way to know if you have it is to have a screening exam. In general, people with no family history of colon cancer should begin screening for the disease at age 50, with repeated tests every 10 years.

If you do have a family history of colon cancer or colon polyps, your physician may recommend that you start screening at an earlier age. The earlier a family member has had color cancer or polyps, the more likely it is to run along genetic lines.

Colonoscopy screening for colon cancer

There are several types of colon cancer screening techniques, but a test called a colonoscopy remains the “gold standard” to evaluate and diagnose both cancerous and precancerous growths.

The most thorough and widely used screening exam, colonoscopy allows the physician to inspect and sample the tissue in the rectum and colon via a long, flexible tube with a built-in camera. The tube is inserted through the rectum, and images from the camera are displayed on a video monitor, which enables the physician to see inflamed tissue or lesions, abnormal growths and other irregularities.

Should any abnormalities be found, they can be easily biopsied or removed during the procedure. While colonoscopy may be uncomfortable, it takes only 15 to 30 minutes, and patients are almost always sedated and usually have no memory of the procedure.

Not all patients, however, are good candidates for colonoscopy. Some may be uncomfortable with the thought of a tube being passed through their colon, or cannot tolerate sedation drugs. Others may have scar tissue or other obstructions that prevent the scope from getting through the bowel. For these patients, a virtual colonoscopy can be a viable alternative.

Comparing virtual and traditional colonoscopy

Also known as CT colonography or CT colonoscopy, VC is a relatively new, non-invasive and easily tolerated technique that uses specialized CT scanning equipment.

Whereas conventional colonoscopy passes the scope through the entire colon, VC uses a very thin tube inserted only into the rectum to inflate the colon with air, enabling the CT scan to take an accurate image. The images are transferred to a video monitor, which creates a detailed picture of the inside of the colon. The physician can then look for the same abnormalities that would be seen with conventional colonoscopy.

Both procedures require the same preparation, in which the patient follows a liquid diet and uses laxatives to completely clear the colon prior to the exam.

However, unlike conventional colonoscopy, there is no need for sedation during a VC, so patients can drive themselves back to home or work immediately after the test and resume their normal activities.

The primary disadvantage of VC is that, should a polyp or other abnormality be found, it cannot be removed or biopsied as it would in a conventional procedure, and the patient still needs to have a conventional colonoscopy.

Virtual colonoscopy is not intended to be a replacement for colonoscopy, and whether it screens as effectively is still in debate. Even so, it is an excellent alternative for those who cannot or choose not to have a conventional colonoscopy.

If you’ve celebrated your 50th birthday and haven’t had a colon cancer screening, talk to your physician about this very important test. It’s a highly effective technique that can save your life.

This Scripps Health and Wellness information was provided by David Roseman, M.D., a gastroenterologist at Scripps Memorial Hospital La Jolla.