Breast Cancer spotlight: BRCA genes
Breast cancer is one of the most common cancers, and scientists have found two genes that play a key role in protecting against it. These genes are BRCA1 and BRCA2 (BReast CAncer gene 1, BReast CAncer gene 2). Under normal situations, these genes are responsible for repairing damaged DNA, which can lead to the development of tumors. Scientists pay attention to these two genes because mutations in these genes can result in increased risk of developing tumors. A mutation is when a gene is changed and does not function properly.
The odds a person with the BRCA1 or BRCA2 gene has a mutation is 1 in 400 (0.25%). Those with mutations also need to be aware that they can pass this mutation onto their children, so increased risk can run in families. This family history is what would lead to someone being tested for BRCA gene mutations in the first place.
We spoke to Corey Smith, an oncology pharmacist at Madison Memorial Hospital’s Cancer Care Center, which is a part of the Huntsman Cancer Institute.
BRCA genes lead to increased risk of breast cancer, are there other genes that we know lead to other types of cancer?
- Corey: BRCA genes are not only important for breast cancer, but also ovarian cancer, prostate cancer, pancreatic cancer, and others that can express a BRCA gene. In terms of increasing likelihood of cancer, BRCA is just one of the genes we test for. We look at genes, but we also look at tumor markers and receptors. Estrogen receptors guide hormonal therapy and the duration of therapy. We test for HER2 positivity, which also guides chemotherapy selection and treatment duration. (An explanation of HER2 by Dr. Timothy J. Moynihan of the Mayo Clinic is attached below). So we not only look at gene expression, but what tumor receptors that cell is producing.
What are some ways that people with the BRCA gene can reduce their risk of developing cancer?
- Corey: Some people choose to undergo prophylactic mastectomy if they are a known carrier for BRCA mutation. This is something the patient should discuss with their primary care physician or oncologist. (A prophylactic mastectomy is when a person has one or both breasts removed to reduce the risk of developing breast cancer).
Does MMH normally test for the BRCA gene?
- Corey: Not every patient gets BRCA tested. If a patient with breast cancer has specific factors that would suggest a BRCA mutation, such as young age (less than 45), significant family history of breast or ovarian cancer, or if they have a triple negative breast cancer then we would test for the mutation. If the patient was positive, then there would be a discussion about testing family members to know their risk of developing cancer.
Explanation of HER2: