Many of the online sites that offer genetic tests that tell you whether you may get cancer are not telling you the whole truth. With the news releases today and yesterday about a "new" genetic test for existing colon cancer, I started searching for similar items on the Internet and came across another one of those "recurring numbers".
This time the number is 5--5% of colon cancers may be associated with genetics. We already know that only 5% of breast cancers are associated with the BRCA1 and BRCA2 genes. Now, we have an additional group of very important cancers that do not appear to have a strong genetic component.
So, what do you do with the results of a genetic test you purchased online:
1. Recognize that the results refer to only 5% of the known associations between the cancer you're concerned about and genetics. The other 95% is not covered by the genetic test.
2. Remember that having one of the breast cancer genes or colon cancer genes does not mean you are destined to have that cancer. These genes (mutated genes, that is) are more likely to be found in those with breast or colon cancer than in the general population. People who have the gene--these are typically identified in family studies--do not necessarity have the cancer. Their chances are higher, but a lot more must be taken into account than the genetic mutation.
So, that genetic test you're interested in only "sees" specific genetic mutations and only 5% of breast or colon cancer is associated with these mutations.
Again, I caution: think about how you will deal with the results of a genetic test if you purchase one and send it in. If you get an answer that says you have the "bad" genes, will you have your breasts or colon removed? If you get an answer that says you do not have the "bad" genes, will you consider yourself safe and stop doing all those things doctors say help us avoid these cancers? Will you be devasted if you later discover you have one of these cancers?
Use the Internet to search for additional information on any test you are considering. Believe only reputable sites and, if you choose to have a test for breast cancer or colon cancer genes, understand the tests' limitations and use the test results as a part of your heath care--not all of it.
Marie Godfrey, PhD