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The Role of Genetics

A minority of breast cancers have a genetic basis. When appropriate, genetic counseling and/or genetic testing may be recommended by the breast surgeon and/or oncologist. On this web page we are providing a very brief overview of the genetics involved with breast cancer, and information on how to learn more. The role of genetics in the diagnosis and treatment of breast cancer can be confusing, so we recommend all our patients speak with their breast surgeon, oncologist, or a genetic counselor if there are any questions.

What is a “BRCA” gene?

Scientists have identified two genes linked to breast cancer, known as the BRCA1 and BRCA2 genes. These genes are believed to play a role in suppressing tumors and thereby reducing the cancer risk. Everyone has these genes (male and female). However, some people have mutations in the BRCA1 or BRCA2 genes – essentially their BRCA genes do not function properly and these patients are at increased risk of certain types of cancer such as breast, ovarian, or prostate cancer. Even if someone has abnormal BRCA genes, it does not necessarily mean that person will get cancer but it may mean an increased risk of cancer.

What percentage of breast cancer is believed to be genetic?

It is currently believed that approximately 75-78% of all breast cancer cases are sporadic mutations – meaning they are not related to a patient’s genetics. Approximately 7-10% of all breast cancer cases are believed to be related to abnormal BRCA genes. The remaining 15% are considered “familial”. This means there is a family history of breast cancer (or ovarian cancer) but no abnormal BRCA genes. There may be other genes involved in these cases which have simply not yet been identified

What is genetic testing?

Genetic testing typically involves a patient first being seen by a genetic counselor. This individual takes a comprehensive medical and family history on the patient. The patient is then advised regarding the details of genetics in breast cancer and a recommendation made regarding genetic testing. The testing itself involves sending a blood sample to a highly specialized laboratory (Myriad Genetics Laboratories). The genes are analyzed and results returned to the center conducting the genetics testing. Patients may then have a second consultation with the genetics counselor to discuss the results and what those results may mean for the patient.

What factors are considered when determining whether a patient should have genetic testing?

  • A patient’s personal cancer history, particularly breast or ovarian cancer
  • Bilateral breast cancer (patients with bilateral breast cancer are more likely to have (abnormal BRCA genes than those with unilateral breast cancer)
  • A family history of breast or ovarian cancer
  • A male with breast cancer in the family (the BRCA genes are carried by both men and women)
  • Breast cancer before the age of 50
  • Ashkenazi/Eastern European Jewish Descent (there is a higher incidence of abnormal BRCA genes in this population than in the general populaton)

How does genetic testing affect the breast reconstruction decision?

A patient who is found to have an abnormal BRCA gene may be advised to consider a prophylactic mastectomy on the non-cancerous breast, or may be advised on a different post-mastectomy treatment course by the oncologist. This may have an impact on the type of reconstruction chosen. As an example, consider a hypothetical patient named Jane who has breast cancer in her left breast and undergoes a unilateral (one sided) mastectomy with reconstruction using a DIEP flap (abdominal tissue). Then later Jane undergoes genetic testing and learns she has an abnormal BRCA gene and is advised to undergo a prophylactic mastectomy on the right side. Because she has already used her abdominal tissues for the first reconstruction, she will now have to choose a different type of reconstruction for the right breast. If genetic counseling was done prior to the original mastectomy and reconstruction she might have chosen to have both mastectomies done originally and been able to have a DIEP done on both breasts at that time.Another way in which genetic testing may affect reconstruction is with regard to recommendations about post-mastectomy treatment such as radiation. If it is known a patient will be having radiation, this may factor into the decision as to the best type of reconstruction for any given patient.

Other than these two factors, however, reconstruction is not affected by BRCA gene anomalies.

It is important to note that genetic testing is not necessary for all patients. Each patient should speak with her breast surgeon and/or oncologist about this.

Does genetic testing affect eligibility for insurance?

Patients are often concerned that abnormal genetic test results may cause them to lose their insurance or be unable to get new insurance in the future. However, HIPAA (the federal legislation that affects many facets of health information) prohibits the use of genetic test results to determine eligibility or rates for insurance. In addition, Texas Bill 75RHB prohibits discrimination in employment or health insurance in group plans of 50 or more. More information about these legislations and insurability can be learned from your genetic counselor.

Where can a patient learn more about genetic testing?

There are a variety of centers in the DFW metroplex, and throughout the country, providing genetic counseling and genetic testing. Check with your physicians for recommendations of a center near you. The information provided on this page is from a presentation given to our office by Becky Althaus, RN, PhD, a genetic counselor with the Baylor W.H. & Peggy Smith Baylor Sammons Breast Center. Information can be obtained from that center at 214-820-9600.

Medical City Dallas Hospital has a Clinical Cancer Genetics program which can be reached at 972-566-3955, fax 469-484-2261. The geneticist there who works with many of our patients is Annette Patterson, MS, CGC.

In addition, Myriad Genetics Laboratories has educational material which can be found at their website at www.myriadtests.com.