Monday, June 7, 2010

Meeting with a Genetic Counselor

Editor's Note: A LifeBridge Health patient recently met with one of our genetic counselors. She graciously agreed to share her story in the hopes that it will help others.

A lot of women in my father’s side of the family have been diagnosed with breast cancer, which is why my doctor recommended that I meet with a genetic counselor. Knowing that one is genetically predisposed to a certain cancer can allow screening to occur more often and start at a younger age in attempts to catch any potential cancer at its earliest stage, when it is the most treatable.

There are two known gene mutations – BRCA1 and BRCA2 – that greatly increase one’s odds of getting breast cancer. That’s because these gene mutations interfere with the body’s ability to suppress tumors in the breast. It turns out that our bodies frequently make abnormal cells. However, the body also has mechanisms to rid itself of these irregular cells. When these mechanisms fail or aren’t working properly (as in the case of BRCA1 and BRCA2 mutation carriers), that’s when cancer can occur. Having the BRCA mutations increase a woman’s risk of breast cancer to anywhere from 60 to 85 percent. These same mutations also increase the odds of getting ovarian cancer to about 45 percent.

I went to the Alvin & Lois Lapidus Cancer Institute to meet with Shannan DeLany Dixon, M.S., C.G.C., a genetic counselor and director of the Master's in Genetic Counseling Program at the University of Maryland School of Medicine. Shannan regularly sees patients at Sinai and Northwest hospitals. First, she asked me questions related to my personal risk for breast cancer, such as when I had my first menstrual cycle, if I was ever pregnant, my age, if I had ever taken birth control pills, and how much I drank alcohol. Experts estimate that about 75 percent of breast cancer cases are attributable to these lifestyle factors and have nothing to do with our genes; 15 percent are caused by a combination of genetic and lifestyle factors; and 10 percent are inevitable based on genetic makeup.

Shannan mapped out my complete family tree, noting which family members had conditions such as breast cancer, severe diabetes, heart disease and stroke. (As part of her job, she searches for all known genetic-related diseases, not only breast cancer.) While my paternal grandmother and both of her sisters had breast cancer, my grandmother was the only one to get it when she was only 39; the other family members were all women in their 50s, 60s and 70s, when breast cancer is not unusual. Shannan mentioned that there could have been an environmental factor in the town in which they lived that would have caused this breast cancer cluster.

If my grandmother’s breast cancer had been caused by the gene mutation and not her environment or lifestyle, there is a 50 percent chance that I would have inherited a mutated gene from my father. However, as long as I haven’t also received the mutation from my mother, I would not have increased risk for breast cancer because of my genes.

Based on my family tree, Shannan estimated that there would be about a 6 percent chance that a genetic test would come back positive for me, which would not necessarily mean that I would have a cancer-causing mutation to my BRCA1 or BRCA2 genes. A positive test result might show “a variant of unknown clinical significance,” because there is some normal variation to BRCA1 and BRCA2 genes that researchers are still sorting out.

As it turns out, I decided not to move forward with the genetic test because my mother’s side of the family is largely cancer-free and no one in my family is known to have had ovarian cancer. (Had either of these factors been otherwise, my decision would be different.) Testing would have been an easy process, involving either a blood sample or a cell specimen collected from the inside of my cheeks. I was surprised to learn that my insurance would have covered almost the entire cost of the test.

Meeting with Shannan gave me tremendous peace of mind. I still run the risk for breast cancer (1 in 8 women will be diagnosed at some point in her life), but I now think it’s unlikely that I have a BRCA1 or BRCA2 gene mutation. This doesn’t mean I can let my guard down. I will still get my annual mammograms and do all that I can through diet and exercise to lead a healthy lifestyle – the best form of cancer prevention.

Do you have an increased risk for breast cancer based on certain lifestyle factors? Take LifeBridge Health’s free risk assessment at Know Your Health. There are also several helpful websites with information on genetics, such as the Family Cancer Genetics Network and Facing Our Risk of Cancer Empowered (FORCE).

1 comment:

ddarcy said...

This is a wonderful entry, and it's great that this patient took the time to write it. I am a genetic counselor, and so I feel compelled to address something which was stated in this blog but which does not apply to BRCA1/2. To inherit an increased risk for breast and ovarian cancer, you do NOT need to inherit a mutation from both parents, like you do with some other conditions. You only need to inherit ONE mutation, from either parent. I believe that most likely this patient was not tested because her relatives with cancer were mostly over 50, and they were 2 and 3 degrees removed from her (a parent is 1 degree, grandparent 2 degrees, etc.). The only relative who had breast cancer in her 30's was her great-aunt, who is a 3rd degree relative. If her grandmother did carry a BRCA mutation, there would be a 50% chance that her father had inherited it. Then the patient would have another 50% risk of inheriting it from him, making her risk only 25% to have inherited her grandmother's mutation, not 50%. The point about her mother's family not having cancer is that there is virtually no chance of a mutation on that side. This is just good news, but it has nothing to do with the risk which could still come from her father's side. I'm sure that she could call her genetic counselor and ask to have this clarified. I do also think that her risk is low for a mutation due to her relatives' ages of diagnosis and their distance (degree). Her mother's side has nothing to do with that particular risk. I know this is confusing -- but I hope it helps.