June 2012 Ask the Expert: Genetics and Risk Assessment
During the month of June, Living Beyond Breast Cancer expert Jill Stopfer, MS, CGC, answered your questions about breast cancer genetics and family risk.
I have already had genetic counseling which identified there was a heritable cancer operating in my family. Researchers told me there could be genes other than BRCA1 and 2 that could be the culprit. Do I need a newer round of counseling? I got my advice 10 years ago.
Question: I have already had genetic counseling which identified that there was clearly a heritable cancer operating in my family. However, researchers told me being tested for BRCA1 and 2 would only show whether those were the “actors” but would not necessarily identify the culprit. There could be BRCA3, 4 and 5, which we have not identified. I am in my 50s and get regular monitoring but have not done any prophylactic surgeries. Do I need a newer round of counseling? I got my advice 10 years ago.
Ms.Stopfer: We know that BRCA1 and BRCA2 are not the only genes that can run in a family and increase the risk for breast and other cancers. In fact, when breast cancer appears in multiple generations, even at early ages, BRCA1 or BRCA2 will provide the explanation only 40-50 percent of the time.
We know there are other genes associated with breast cancer risk, and in the near future there will be many more genetic testing opportunities for families with strong patterns of breast cancer. Genetic testing is not 100 percent sensitive, meaning it is possible for the lab to not be able to “see” a problem, or a mutation in a gene, due to limitations in lab methods.
Since lab methods have evolved over the last 10 years, it may be worthwhile to check in with a cancer genetics expert again to determine whether there are other opportunities available now that have some reasonable chance of providing clinically useful information.
Family histories can evolve over time as well. If there are new diagnoses of cancer in your family, it’s possible that there maybe a hereditary cancer condition other than BRCA1 or BRCA2 that could be the culprit.
Checking in periodically with a cancer genetics expert is a good idea so you don’t miss out on potentially helpful opportunities to clarify the situation for yourself and for your family.
Ms.Stopfer: It’s true that genetic testing can be expensive. However, most people who have insurance as well as a significant chance of a mutation in a specific cancer predisposition gene will have coverage, at least in part, for testing.
Medicare does pay for genetic testing for those who have had a cancer diagnosis, such as breast or ovarian cancer, when appropriate criteria are met. Medicare does not cover genetic testing for relatives who have never had a cancer diagnosis.
Unfortunately, Medicaid does not cover genetic testing for BRCA1/2 in most instances. Occasionally a Medicaid replacement plan such as Keystone Mercy covers genetic testing.
It’s important that whoever is arranging the genetic testing is familiar with how to properly send in the sample to maximize the chances of insurance coverage. Typically you will have an opportunity to cancel the test if you learn you do not have coverage or acceptable coverage during the pre-authorization process. Those with expertise in cancer genetics will know how to make these arrangements.
Ms.Stopfer: Results from genetic testing are not always straightforward. When a mutation is found, this is referred to as a“positive result,” meaning something was found to be changed in a harmful way in the particular gene being studied.
A gene is spelled with chemical letters that make up the genetic code. These letters must be in the proper order, without missing or extra letters inserted into the code. Usually a laboratory can tell whether or not the genetic code is spelled correctly, but not always.
Our genetic codes are not identical. Since the genetic code that makes up the both BRCA1 and BRCA2 contains thousands of letters, there is normal variability in the spelling of the genetic code between people.
Occasionally the lab will see particular sequence in the genetic code, and there is uncertainty surrounding how to classify this code—it could represent normal variability, but the sequence change could also be harmful and lead to a non-functional gene. These results, called variants of uncertain significance, eventually get reclassified as either harmful or harmless. But the process could take time, and interim recommendations need to be made that take into account the level of suspicion you have about your family history as well as the results.
If the lab feels that a mutation, or harmful change, is present in the genetic code, then this result should be straightforward and reliable provided testing was done in a certified clinical lab. If results are negative, or if no mutation is found, the significance of this finding will depend on whether or not there is a known mutation in your family. If someone else has been tested and the source of cancer risk in your family is known because a mutation has been found, then negative genetic testing results are very meaningful.
For example, let’s say Martha has genetic testing since she had breast cancer diagnosed at an early age. Martha is found to have a BRCA1 mutation. Martha’s daughter Sophia gets tested, and Sophia has a negative result. This is a true negative. We know there is a BRCA1 mutation in the family, and Sophia did not inherit it. Sophia’s risk is now the same as the average woman’s risk for cancer.
In another family, Kathy is cancer free. She is tested because she has a mother and a sister with breast cancer. Kathy is not found to have a mutation in either BRCA1 or BRCA2. What can we conclude? Since we don’t know why Kathy’s mother and sister got breast cancer, this is NOT a true negative result. It’s possible a gene other than BRCA1 or BRCA2 is the culprit in this family. If a different gene or even genes is the real source of risk in this family, then her negative BRCA1 and 2 testing has no bearing on her actual cancer risks.
Again, undergoing testing with a cancer genetics program will ensure that no matter what the result, it is properly interpreted.
Ms.Stopfer: Having an inherited mutation in BRCA1 or BRCA2 mutation sets one at increased risk for both breast and ovarian cancer. Some women will develop one cancer, while others will develop more than one cancer.
It is also possible to live to a mature age and never develop any form of cancer, despite being at increased risk. Having breast cancer does not mean your chances for developing ovarian cancer are lower.
In general, women with inherited mutations in BRCA1or BRCA2 have about a 60-80 percent chance of developing breast cancer and up to a 50 percent chance for developing a second breast cancer.
Women with mutations in BRCA1 have a 30-45 percent chance of developing ovarian cancer, and women with BRCA2 mutations have a 10-20 percent chance of developing ovarian cancer. Interventions are available that lower these risks and maximize chances for early diagnosis and cure.