• Important Facts about Colorectal Cancer
• Primary Prevention
• Secondary Prevention
• Fecal Occult Blood Test (FOBT)
• Flexible Sigmoidoscopy
• Colonoscopy
• Virtual Colonoscopy
• Conclusion
• Additional Resources
• References

Important Facts about Colorectal Cancer

Colorectal cancer – cancer in the rectum and colon (the large intestine) – is the second leading cause of cancer death in the United States, for men and women. In 2006, it is predicted to cause nearly 55,000 deaths, most commonly in people 50 or older. Warn-ing signs for colorectal cancer include rectal bleeding, change in bowel habits, or blood in the stool. Unfortunately, most symptoms only occur when cancer is more advanced.

Many patients develop polyps in the colon. Polyps can turn into cancer over time but early on they usually produce no symptoms. If they are found and removed, then a person’s chance of developing colon cancer is greatly reduced.
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Primary Prevention

There are lifestyle measures associated with possible reductions in the incidence of colorectal cancer. Some of these are:

• Diets with more fish
  
• Adequate dietary fiber and less red meat
  
• Calcium
  
• Exercise

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Secondary Prevention

Early detection of colorectal cancers by screening is now well established as a standard of care. Not screening is no longer an option. With early detection, the five year survival rate for colon cancer before it has spread is nearly 91 percent. Unfortunately, only about 40 percent of eligible adults get regular screening. Most people cite embarrassment or fear of discomfort as their reasons for not doing screening.There are currently three accepted methods of screening. The screening test currently recommended for those at increased risk is colonoscopy. Only you, in discussion with your health care provider, can decide which test is right for you. No test is 100 percent sensitive.
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Fecal Occult Blood Test (FOBT)

For this test, you are given a kit to take home. You follow a mildly restricted diet for a few days, during which you collect a small amount from each of three separate bowel movements. You mail the kit back to the lab and the samples are analyzed for blood. If there is no blood, you simply repeat the test in one year. If there is blood in any of the samples, you see a gastroenterologist to have a colonoscopy to look for a bleeding cancer or polyp. Sometimes no cancer or polyp is found (this is called a "false positive test"). Conversely, a negative test, while reassuring, does not entirely rule out a cancer or polyp. Some studies suggest a miss rate of up to 50 percent.

It is also important to realize that most patients with a positive test do NOT have cancer.

This test is done yearly and is often combined with flexible sigmoidoscopy.
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Flexible Sigmoidoscopy

This is a procedure done by a trained endoscopist or gastroenterologist. You are required to prepare with a laxative the day before and on the morning of the procedure. The procedure lasts about 10 to 20 min-utes. A tube is inserted in your anus and advanced up to 25 inches (to the splenic flexure – see diagram). Approximately a quarter to a third of the colon is visualized on this type of examination.

If cancers or polyps are found, they can be removed and sent for analysis. If a cancer or polyp is found, there is a good chance that there are also cancers or polyps higher up in the colon, and you will be referred for a full colonoscopy. If the flexible sigmoidoscopy shows no cancers or polyps, the test is repeated in five years.

This test is believed to be more effective if combined with a yearly FOBT (mentioned earlier).

This test requires no sedation and you can return to work shortly after having it done. Most people feel moderate discomfort (due to cramping) during the test, and the test can be stopped if it is too uncomfortable. There is a very small chance of bleeding or intestinal perforation from this test.

Current data suggests that sigmoidoscopy combined with FOBT will detect about 75 percent of patients with colon cancer. If you have a normal flexible sig-moidoscopy, there is a small chance that there is still an undetected cancer or precancerous polyp higher up in the intestine (that might be found with colo-noscopy).


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Colonoscopy

This is a procedure done only by the gastroenterolo-gist. As with the flexible sigmoidoscopy, it requires preparatory cleaning of the colon. It lasts 30 to 60 min-utes, requires sedation and necessitates a day off from work to recover. A flexible tube is inserted in your anus and advanced to the cecum, allowing your entire colon to be surveyed. Success in reaching the cecum is more than 90 percent. Because of the sedation, there is usu-ally little or no discomfort. There is, however, a higher rate of serious complications. Bleeding, perforation, emergent surgery or complications from the anesthe-sia are the major risks and can occur in one to two in 1,000 cases (0.1 percent to 0.2 percent).

Colonoscopy detects 90 percent to 95 percent of colorectal cancers. If normal, the test is usually repeated every 10 years.

You should have earlier and more frequent screenings via colonoscopy if you have:

• a close relative with colorectal cancer or certain kinds of polyps
  
• a family history of polyposis
  
• a personal history of polyps or cancer
  
• inflammatory bowel disease

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Virtual Colonoscopy

Virtual Colonoscopy, also known as CT colonography, is an X-ray examination of the large intestine. It has potential to be of value in screening yet its role is still uncertain. Cleansing of the colon is still required and if polyps are discovered on this exam, traditional colonoscopy is still required. No expert panel or na-tional organization has yet endorsed the use of Virtual Colonoscopy for colorectal cancer screening.
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Conclusion

• Any screening test is better than none.
  
  
• Under most circumstances, none of the tests are terribly unpleasant or highly risky.
  
  
• Only you (in discussion with your doctor) can decide which test is right for you.

Insurance coverage for screenings varies. Always check with your health plan about coverage and pre-authorization requirements.
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Additional Resources

You may borrow a video on Colonoscopy from Camino Medical Group Health Education Department; 408-523-3222 or view it online at www.caminomedical.org, Health Education under Audio & Video Library.

National Cancer Institute

Cancer Research and Prevention Foundation

Centers for Disease Control and Prevention

American Cancer Society
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References

Winawer SJ, Fletcher RH, Miller L et al. Colorectal cancer screening: clinical guidelines and rationale. Gastroenterology 1997; 112: 594-642.

Woolf SH. The Best Screening Test for Colorectal Cancer - A Personal Choice. New England Journal of Medicine 2000; 343: 1641.

American Cancer Society Colon Cancer Fact Sheet: The Basics JAMA 2003; 289:1288-1302

Authors

Antoinette Rose, M.D., and Jay Ladenheim, M.D., Gastroenterology.

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