Colon Cancer and Polyp - Screening Guidelines

A year ago I had colonoscopy, a procedure in which a viewing tube is put into the rectum to look at the colon, the large intestine. This procedure had been recommended to me because of a number of factors. My father had cancer of the colon. Later my brother had colonoscopy and was found to have what are called adenomatous polyps, little finger-like protrusions from the inside wall of the colon, that start as benign growths but have a tendency to become cancerous.

My colonoscopy yielded 17 polyps. All were removed through the colonoscope and all proved to be benign, not cancer.

At higher risk for colon cancer

When one family member has an adenomatous polyp or cancer of the colon or rectum, their close relatives (their parents, sisters, brothers, and children) all have a higher risk of developing colon or rectal cancer than does the general population.

Cancer-screening guidelines may therefore be of special value to anyone with a family member who has had colon or rectal cancer (colorectal cancer) or an adenomatous polyp.

These guidelines are for everyone but especially for people who may be at elevated risk for developing colon or rectal cancer but have not yet been found to have it. They are to help the patients and their doctors decide which cancer examinations should be done and when.

If a person has been found to have colon or rectal cancer or polyps, they should continue to follow the doctor's recommendations for examinations.

Finding out a person's level of risk for colorectal cancer

Everyone has a level of risk for developing colorectal cancer, whether that risk be very low or very high or somewhere between those extremes. To find a person's level of risk, please read these descriptions:

• Level 1 risk: The person does not have a family member who has had colorectal cancer or adenomatous polyps. Or the person has a family member who had colorectal cancer or a polyp but the affected family member is not their parent, sister, brother or child.
• Level 2 risk: The person has a parent, sister, brother or child who had colon or rectal cancer after the age of 50 or a polyp after age 60.
• Level 3 risk: The person has a parent, sister, brother or child who had colon or rectal cancer before age 50 or a polyp before age 60. Or the person has two close relatives (parent, sister, brother, child) who had colon or rectal cancer after the age of 50 and/or an adenomatous polyp at any age.
• Level 4 risk: The person has an even stronger family history. For example, their father and his sister both had colorectal cancer before age 50.

The guidelines below are based upon those of the Hereditary Colorectal Cancer Program at Johns Hopkins which were developed upon the recommendations of such groups as the American Cancer Society and the American College of Gastroenterology together with the expert medical opinion of the Hereditary Colorectal Cancer Program.

Level 1 risk -- screening guidelines

• Yearly test for blood in stool, starting at age 50.
• Flexible sigmoidoscopy with a digital rectal exam every 5 years, starting at age 50.

Sigmoidoscopy is a procedure in which a viewing tube is inserted into the rectum to look at the lower colon and rectum. Other alternative exams include what is called a double-contrast barium enema every 5-10 years or a colonoscopy every 10 years (both with a digital rectal exam). These options are best discussed with the doctor.

Level 2 risk -- screening guidelines

Doctors are uncertain about the best guidelines for screening for level 2 risk people. It is recommended that the person discuss the guidelines with their doctor to decide what is best. Some factors, which may influence the decision, include:

• The age at which the parent, sister, brother or child was diagnosed with colon or rectal cancer.
• The presence of colon or rectal cancer in other, more distant, family members.
• The presence of other cancers in the family.

Level 3 risk -- screening guidelines

• Colonoscopy with a digital rectal exam every 3-5 years, beginning either at age 35-40 or 5-10 years earlier than the earliest age at which colon or rectal cancer occurred in your family, whichever is younger.
• A yearly test for blood in stool, beginning at age of the first colonoscopy.

These are broad guidelines. The patient should discuss these guidelines with their doctor to decide what age and testing interval is best for them. Flexible sigmoidoscopy and air-contrast barium enema exam may be substituted for colonoscopy but are not preferred.

Level 4 risk - screening guidelines

• Colonoscopy with digital rectal exam every 1-3 years, beginning either at age 25 or 5-10 years earlier than the earliest age at which colon or rectal cancer occurred in your family, whichever is younger.
• Yearly test for blood in stool, beginning at age of the first colonoscopy.
• Genetic counseling and testing, if appropriate, for genes associated with hereditary colorectal cancer.

Conclusion

Please note that all of these recommendations are general guidelines. No matter what level risk a person has, it is best to discuss the guidelines with the doctor to decide what age and testing interval might be best in their particular case.

Cancer of the colon can be prevented by removing the polyps. And when colon cancer does occur, it can often be cured when detected very early. These are the aims of screening.

For more information, please visit our Colon Cancer Center.

Last Editorial Review: 7/7/2004