Is Breast Cancer Genetic?

About 5-10% of breast cancers are thought to be hereditary, caused by abnormal genes passed from parent to child. Researchers study genetic mutations that can confer increased breast cancer risk to patients. BRCA1 (BReast CAncer gene 1) and BRCA2 (BReast CAncer gene 2) 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 germ-line 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. These DNA changes that negatively affect health care called mutations.

What’s the BRCA Gene?

BRCA1 and BRCA2 are tumor suppressor genes. When they’re working normally, these genes encode proteins that function to repair DNA. This helps keep breast, ovarian, and other types of cells from growing and dividing too rapidly or in an uncontrolled way.

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. 

BRCA Genetic Mutations

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. BRCA1 and BRCA2 mutations account for approximately 7% of all breast cancers.

Women who are diagnosed with breast cancer and have a BRCA1 or BRCA2 mutation may have a family history of breast cancer, ovarian cancer, or other cancers. The majority of women with breast cancer do not carry a genetic predisposition and do not have a family history.

You are more likely to have a genetic mutation linked to breast cancer if:

  • You or a relative has had breast cancer diagnosed before age 50.
  • There’s both breast and ovarian cancer on the same side of the family or in a single individual.
  • You or a relative has had a triple-negative breast cancer.
  • Women in your family have had cancer in both breasts.
  • You’re of Ashkenazi Jewish (Eastern European) heritage and have a family or personal history of breast cancer.
  • A man in your family has had breast cancer.
  • There’s a known abnormal breast cancer gene in your family.

How to Lower the Risk of Breast Cancer

If you know you have an abnormal gene linked to breast cancer, there are some lifestyle choices you can make to keep your risk as low as it can be:

  • Maintaining a healthy weight
  • Exercising regularly
  • Limiting alcohol
  • Eating nutritious food

Learn More About the Hereditary Factors of Breast Cancer with Baptist Health

While a minority of breast cancer cases are hereditary, it’s important to assess your risk factors. Take a personal Health Risk Assessment today to learn more and understand your personal risk factors and what you can do to lower them. 


Sources:
U.S. National Library of Medicine
BreastCancer.org
American Cancer Society
National Breast Cancer Foundation
CDC

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