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Cancer Genetics

Colon Cancer and Genetic Studies

11/25/2000

Question:

I would like to know about any genetic studies being done on colon cancer patients. I am concerned because I was diagnosed at the age of 49 and I have two sons. Any information would be appreciated.

Answer:

We agree that it is important to determine whether or not your colon cancer was due to a hereditary predisposition. Around 10-15% of colon cancers are said to be hereditary. (The website for a Saturday Post article is below that gives a nice overview of the genetics of colon cancer.)

We are certainly much more suspicious that a colon cancer may have been hereditary when an individual is diagnosed under age 50. The most common hereditary colon cancer syndrome is called Hereditary Nonpolyposis Colorectal Cancer (HNPCC). You can find more information about this syndrome at the Johns Hopkins website that is below.

As you`ll learn from your reading, there are tests that can be performed on a piece of your colon tumor to determine whether it is likely or not that you have HNPCC. A piece of your colon tumor can be found stored in wax at the hospital that performed your surgery. If the tumor test (either microsatellite instability or immunohistochemistry) indicates that you are likely to have HNPCC, then genetic testing for the genes responsible for HNPCC may be indicated.

The research studies available vary from one city or even one institution to the next. To find out about genetic studies on colon cancer that are going on in your area, you should contact your local cancer genetics professionals. You can find a local cancer genetic counselor at the National Cancer Institute`s Directory of Cancer Genetics Professionals (website below). If you are not eligible for a research study, this testing can still be offered on a clinical basis through your local cancer genetics professionals. However, you would be charged for the testing in this case. This is also important because there are other hereditary syndromes (in addition to HNPCC) that can cause colon cancer and only a careful evaluation with a cancer genetics team can help make the proper diagnosis.

If you find out that your colon cancer was hereditary, your sons may be able to benefit from genetic testing to determine whether or not they have inherited the increased risk for developing colon cancer themselves. If they did not inherit the gene responsible for colon cancer (assuming one had been found in you), they would have the general population risk for developing colon cancer. If they did inherit the gene responsible, they would be advised to have earlier and more frequent colon cancer screening.

Related Resources:

National Cancer Institute Cancer Genetics Directory

For more information:

Go to the Cancer Genetics health topic, where you can:

Response by:

Heather L Hampel, MS, CGC Heather L Hampel, MS, CGC
Cancer Genetic Counselor
College of Medicine
The Ohio State University

Judith A Westman, MD Judith A Westman, MD
Associate Professor, Clinical Internal Medicine, Pediatrics and Medical Biochemistry
College of Medicine
The Ohio State University