Q: Do I really need a colonoscopy to screen for colon cancer?

Ask Our Expert About Colonoscopies

About Our Expert

Linda Lapos, M.D. Colon-Rectal surgeon at Lehigh Valley Hospital and Health Network

• Do I really need a colonoscopy to screen for colon cancer?
  
• How does a colonoscopy prevent colon cancer?
  
• How common is colon cancer?
  
• How does a colonoscopy work?
  
• I heard that the preparation is the most difficult part. Is this true?
  
• Are there risks to a colonoscopy?
  
• Will I feel pain when it's over?
  
• Aren't there other colon cancer tests I can take that are easier?
  
• When should I be tested?
  
• How often do I need the test?
  
• If I have cancer, then what?
  

Q: Do I really need a colonoscopy to screen for colon cancer?

A: Yes, colonoscopies are the most accurate way to screen for and also prevent this cancer.

Q: How does a colonoscopy prevent colon cancer?

A: During a colonoscopy, doctors can remove polyps growing in the lining of the colon. These small, mushroom-like growths take about 5-8 years to become cancerous. By finding and removing them, we can prevent cancer from developing.

Q: How common is colon cancer?

A: It is the third most common cancer in men (behind lung and prostate cancer) and women (behind lung and breast cancer). For men and women combined, it is the second most common cancer. But we believe that many of these cases could be prevented if more people had colonoscopies.

Q: How does a colonoscopy work?

A: To prepare for a colonoscopy, you must clear out your colon (large intestine). A day or two before the procedure, you begin a liquid diet and take laxatives in liquid or pill form.

The colonoscopy itself is done under mild anesthesia—not because the procedure is painful, but to relieve any anxiety you may be feeling. The doctor inserts a thin flexible telescope called a colonoscope into your rectum and moves it 3 ½ feet through your colon. The colonoscope sends images to a computer showing the doctor the lining of your colon as the scope moves through it. If your doctor finds a polyp, it can be removed and tested for cancer. The whole procedure takes between 15 and 45 minutes.

Q: I heard that the preparation is the most difficult part. Is this true?

A: Many people think so, but preparation is getting easier because there are more options to choose from now. Pills are somewhat smaller and easier to swallow, and you can take different combinations of pills and liquid, depending on your personal preference.

Q: Are there risks to a colonoscopy?

A: Colonoscopies are usually very safe, but every medical procedure has risks. In this case, the risks include colon tears; bleeding after polyp removal; infection; overlooked polyps; or reactions to anesthesia. These problems are rare and can be corrected.

Q: Will I feel pain when it's over?

A: No. Generally, the only side-effects are intestinal gas and a little blood in your stool for a day or two after the test.

Q: Aren't there other colon cancer tests I can take that are easier?

A: Yes, there are other tests, but none are as accurate:

• Sigmoidoscopy is similar to colonoscopy, but examines only part of the colon. This test doesn’t require anesthesia or as much preparation. But it misses polyps that a colonoscopy will see.
• Fecal occult tests examine a stool sample for blood. They are the easiest tests, but also the least accurate.
• Virtual colonoscopies are the newest tests, using a CT scan rather than a colonoscope to examine your colon. But they still require preparation and are not as accurate as originally thought. They seem to be most useful when a colonoscopy does not reach through the entire colon. This may happen if the colon is longer than usual or has a kink in it. Then the virtual test can see the unexamined part of the colon.

Keep in mind that if any of these other tests detect or suspect a polyp, you will still need a colonoscopy to remove it.

Q: When should I be tested?

A: If you do not have a family history, symptoms or other risk factors, have your first colonoscopy at age 50. If you have a family history — your parent, sibling or child had colon cancer — start 10 years before the age at which your family member was diagnosed. If you have risk factors (chronic inflammation of the colon, also called ulcerative colitis) or symptoms (blood in your stool or a major change in your bowel movements), then have the test right away.

Q: How often do I need the test?

A: If no polyps are detected, you should not need another test for up to 10 years. Your doctor can determine the exact time, depending on your age, other risk factors and family history.

Q: If I have cancer, then what?

A: If cancer is detected, removing the polyp may be enough. Sometimes a section of the colon must be removed, but the two ends are connected easily, so your bowel functions should return to normal. Sometimes chemotherapy and radiation therapy will be required.

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