Is Breast Cancer Genetic? Understanding Genes and Hereditary Risk

About 5 to 10% of breast cancers are thought to be hereditary, meaning they are caused by abnormal genes passed from parent to child. BRCA1 (Beast CAncer gene 1) and BRCA2 gene mutations are the most common, but there are many other genes that, when mutated, can increase a patient’s breast cancer risk.

How Is Breast Cancer Inherited?

Genes are short segments of DNA (deoxyribonucleic acid) found in chromosomes. DNA contains the instructions for building proteins. Proteins control the structure and function of all the cells that make up your body.

There are two types of DNA changes: those that are inherited and those that happen over time. Inherited DNA changes are passed down from parent to child. Inherited DNA changes are called germline alterations or mutations. DNA changes that happen over the course of a lifetime, as a result of natural aging or exposure to chemicals in the environment, are called somatic mutations.

Some DNA changes are harmless, but others can cause disease or other health issues. DNA changes that negatively affect health are called mutations.

What Are the BRCA1 and BRCA2 Genes?

BRCA1 and BRCA2 are tumor suppressor genes. When functioning normally, these genes produce proteins that repair damaged DNA and keep cells in the breasts, ovaries and other tissues from dividing uncontrollably.

Sometimes, a change or mutation occurs in the BRCA genes that prevents them from working normally. This raises a person’s risk for breast, ovarian and other cancers.

Who Should Consider Genetic Testing for Breast Cancer?

Many inherited cases of breast cancer are associated with mutations in two genes: BRCA1 and BRCA2. These genes pass from generation to generation. When the genes are mutated, the proteins don’t function normally and cancer risk increases. Inherited BRCA1 and BRCA2 mutations account for roughly 7% of all breast cancer diagnoses.

The majority of women with breast cancer don’t have a genetic predisposition or a family history of the disease. However, your physician might recommend genetic counseling or testing if any of the following factors apply to you or your family:

• You or a relative has had breast cancer diagnosed before age 50.
• A family member received a diagnosis of both breast and ovarian cancer.
• You or a relative received a triple-negative breast cancer diagnosis.
• Multiple relatives on the same side of the family have had breast cancer.
• Women in your family have had cancer in both breasts.
• You are of Ashkenazi Jewish (Eastern European) heritage and have a family or personal history of breast cancer.
• A male family member has had breast cancer.
• A family member has a documented inherited gene mutation.

What Are the Symptoms of Breast Cancer?

Noticing changes to your breasts can help you detect problems early. Contact your physician if any of the following occur:

• A new lump or firm area develops in your breast tissue.
• A lump or swelling appears under your arm or near your collarbone. You experience thickening, swelling or unexplained enlargement in any part of your breast.
• The skin on your breast becomes dimpled, puckered or irritated.
• The skin on your nipple or breast surface appears red, flaky, peeling or scaly.
• You feel persistent pain in the nipple area or anywhere across your breast.
• Your nipple begins pulling inward or changes its usual position.
• Spontaneous discharge other than breast milk, including clear fluid or blood, leaks from your nipple.
• The overall shape, contour or size of your breast changes noticeably.

How Can You Lower Your Risk of Breast Cancer?

Taking steps to lower your breast cancer risk is important, especially if you have an abnormal gene linked to the disease. Lifestyle choices you can make to help keep your risk as low as possible include:

• Maintain a healthy weight.
• Exercise regularly.
• Limit your alcohol consumption.
• Eat nutritious food.

Learn More About Breast Cancer and Genetics From Baptist Health

While a small percentage of breast cancer cases are hereditary, it is important to assess your risk factors. Take a Health Risk Assessment today to learn more. If you have been diagnosed with cancer, learn more about cancer care at Baptist Health.