The Link Between Genetics and Breast Cancer
You might be surprised to learn that most people who develop breast cancer have no family history of the disease. We tend to assume diseases mostly run in families - and many of them do. Yet researchers believe only 10-15% of breast cancers are caused by inherited genetic factors that are passed down through the generations by DNA.
Understanding your own hereditary risk for breast cancer, as well as any other risk factors in your life, will help you and your doctor make medical choices that suit your specific health needs.
What Is the Breast Cancer Gene?
Scientists have discovered that the BRCA1 and BRCA2 genes are most commonly associated with a higher risk for breast cancer, when affected by inherited mutations. While approximately 12% of all women in the U.S. develop breast cancer at some point in their lives, a much higher 72% of women with the BRCA1 gene will develop the disease. For those who have BRCA2, the rate of breast cancer development is only slightly lower at 69%.
While both men and women can develop breast cancer, it is much more common in women. Only 0.1 percent of the male population will develop breast cancer. However, that number jumps to 8% for men who carry the BRCA2 gene.
Other genes with inherited mutations that represent an increased risk for developing breast cancer include RAD51D, ATM, CDH1, and CHEK2. Some breast cancer genes are more common in people of certain races or ethnicities.
How Family History Affects Breast Cancer Risk
Most people who develop breast cancer have no family history of the disease. However, it’s important to know that if breast cancer does run in your family, your risk increases.
If a first-degree relative - meaning a mother, sister, or daughter - had breast cancer, your risk almost doubles. Two first-degree relatives with breast cancer increases your risk by almost 3-fold.
Other Risk Factors for Breast Cancer
Higher risk through family history aside, genetic factors are not the only ones that influence your likelihood of developing breast cancer. Environmental, health, and lifestyle factors can also all play a role. Other risk factors include, but are not limited to:
- Being born female
- Age (most cases are found in women 55+)
- Having dense breast tissue
- Having certain benign breast conditions, such as fibrosis and mild hyperplasia
- Going through menopause later
- Radiation exposure
- Alcohol consumption
- Sedentary lifestyle
- Poor diet
While some of these risk factors are things you can’t change, such as dense breast tissue or age, a doctor might recommend you maintain a healthy diet and get regular physical activity to minimize your risk of developing breast cancer.
A doctor might also tell you to consider getting regular mammograms, in order to detect any presence of cancer at the earliest possible state. Current guidelines from the United States Preventive Services Task Force recommend women aged 50-74 with average risk for breast cancer have a mammogram every two years. They also recommend women talk to their doctor about when and whether they should have a mammogram starting at age 40.
What to Know Before You Conduct DNA Testing
Women who are concerned about their genetic or other risk factors for breast cancer should speak with their health care team. They can advise you on how to minimize your risk, and might refer you to a genetic counselor for testing depending on any family history of the disease or other factors.
One such test is the BRCA blood test, which uses DNA analysis to identify harmful mutations in both the BRCA1 and BRCA2 genes. This test is generally only conducted on those with a family history of breast cancer.
If you’ve already taken an at-home DNA test and found results that suggest a genetic risk for breast cancer, bring those results to your doctor to discuss additional testing options and next steps.
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