Considering genetic testing for colon and breast cancers

Timothy C. Hoops, MD
Last Modified: February 3, 2002

Dear OncoLink "Ask The Experts,"

I am a 48 yr.old white female who was diagnosed with adenocarcinoma of the colon contained within a polyp. I have a strong family history. My father died of pancreatic cancer at the age of 79. My mother was diagnosed with breast cancer at the age of 46. She was cancer free until 1988 when she was diagnosed with colon cancer. I considered genetic screening. I decided not to pursue it because (a) it was very expensive and (b) I had heard that genetic testing only screens for colon and breast cancer. I asked myself if genetic testing would change my approach to preventing cancer. My question. Would a person with my history benefit from genetic testing?

Timothy C. Hoops, MD, Clinical Assistant Professor of Medicine in the Gastroenterology Division at the University of Pennsylvania and Director of Gastroenterology at Penn Medicine at Radnor, responds:

With your history of colon cancer already, you know that you are at increased risk for future colon cancer. Genetic testing, if a familial colon cancer syndrome were present, would confirm this and possibly tell you that you have a higher risk. The recommendations at this time would be the same that is colonoscopic surveillance.

If it were found that you had a genetic mutation suggesting hereditary nonpolyposis colorectal cancer (HNPCC), you would probably decrease your surveillance intervals to two years as opposed to 3 to 5 years. However, your history suggests but does not clearly support the possibility of HNPCC unless there are other members of your family with cancer. The chance of finding a mutation decreases with the fewer criteria a family has for the inherited syndromes. The main benefit of finding a positive test in you would be to predict risk in other unaffected family members. A negative test would not rule out an inherited syndrome, as only 60 to 70% of well-defined families will have a detectable genetic mutation. Testing your cancer first might increase the chance of finding a mutation, but it still may not help. As such, unless you have a burning desire to know, and the funds to pay for it, genetic testing probably does not play an essential role in your decisions for your health maintenance.

OncoLink has joined forces with the National Colorectal Research Alliance to help their scientists study the risk factors associated with colorectal cancer and identify potential preventive and treatment therapies. You and your family may be interested in taking our survey. This confidential survey was developed by cancer experts as an interactive way to help our leading scientists study families with a history of colorectal cancer. OncoLink/National Colorectal Cancer Research Alliance prevention database