At the July MS/Cancer conference call, Ksenia Koon, the Breast Cancer Education and Outreach administrator at the Seattle Cancer Care Alliance, led a discussion about breast cancer genetics.
Koon started the discussion by referring to the work of geneticist Dr. Mary-Claire King, whose research lead to the identification of the BRCA1 and BRCA 2 genes in the 1990s. King showed that these two genes, BRCA1 and BRCA2, were responsible for some familial breast and ovarian cancers. Mutations or changes in the BRCA genes can lead to an increased risk for breast and ovarian cancer.
In some families breast and ovarian cancer occurs in multiple generations, sometimes with diagnosis at an early age. King’s research aimed to identify why an increased incidence of breast cancer is in certain families.
Breast cancer occurrence is common and affects one in eight women. Several factors affect an individual’s lifetime risk of breast cancer: exogenous hormone use, age, gender, number of children and age at first pregnancy, to name a few.
Koon explained that family history also plays a role in an individual’s risk for breast cancer. However, simply having a family history of breast cancer does not mean with certainty that an individual themselves has an underlying gene mutation. Although a mutation or change in one of the BRCA1 or BRCA2 genes can increase an individual’s lifetime risk for certain types as cancer, it does not guarantee that an individual will develop cancer. In the case of BRCA1 and BRCA2, testing is available.
Everyone has two copies of their genes: one inherited from their mother’s side of the family and one from the father’s side of the family. As such, every person has one copy of the BRCA1 and BRCA2 gene inherited from the mother’s side of the family and one from the father’s side of the family. Consequently, an inherited predisposition for cancers related to these genes can be inherited from either a maternal or paternal side of the family.
Research studies have shown that having a genetic mutation in the BRCA genes may increase an individual’s lifetime risk of breast cancer. In some studies this lifetime risk has been shown to be as high as 85 percent.
If considering genetic testing, talk to your health provider about your family history of cancer on your mother’s and your father’s side of your family. Your health provider may suggest you meet with a genetic counselor to explore the implications and process of genetic testing.
What can happen if a person has genetic testing and finds he or she has a mutation in the BRAC 1 or BRAC 2 gene?
Not everyone feels the same away about learning that type of information. Some people feel empowered to take charge of their health surveillance. With this information, and in consultation with their health providers, they may opt for increased breast and ovarian cancer screening. Others may consider removal of their breasts or ovaries before a cancer has even developed (propholactic mastectomy or prophylactic oophorectomy).
Even with these surgeries, an individual’s risk for developing cancer does not become zero, but it may be reduced. This type of surgical approach may seem extreme to some people, but for others this approach can make sense depending on a host of factors. This is why the decision to undergo genetic testing is such a personal one and deserves special consideration. A lot comes with learning this type of information, and an individual who decides to undergo testing should explore how they might deal with learning this type of information. Because we are all different, there is no right or wrong answer.
In clarifying a question, Koon said a blood test for cancer biomarkers such as CA125 or tumor testing such as ER status is different from genetic testing. It is important to understand what type of testing is being referred to understand “positive” or “negative” cancer testing results.
To find out more about hereditary cancer, a list of genetic counselors can be found on the National Society of Genetic Counselors website at www.nsgc.org.