What is Hereditary Breast and Ovarian Cancer?

By Sara Bondell - September 30, 2019

Although most breast and ovarian cancers occur randomly, about 15% of breast cancer and 20% of ovarian cancer cases are caused by genetic mutations, most commonly in the BRCA1 or BRCA2 genes. BRCA gene mutations can be inherited from either your mother or father, and only one copy of the mutation is needed to have an increased cancer risk.

What are the BRCA genes?
BRCA1 and BRCA2 are genes that produce proteins that help repair damaged DNA, and therefore play a role in ensuring the stability of each cell’s genetic material. When either of these genes are mutated, DNA damage may not be repaired properly and cells are more likely to develop additional genetic alterations that can lead to cancer.

Specific inherited mutations in BRCA1 and BRCA2 most commonly increase the risk of breast and ovarian cancers, but also have been associated with increased risk in other cancers such as pancreatic cancer, melanoma and prostate cancer.

How much does having a BRCA mutation increase my risk of cancer?
About 12% of women in the general population will develop breast cancer, but recent studies estimate about 72% of women who inherit a harmful BRCA1 and 69% of women who inherit a harmful BRCA2 mutation will develop breast cancer by age 80.

For ovarian cancer, about 1.3% of women will develop the disease, compared to an estimated 44% of women who inherit a harmful BRCA1 mutation and about 17% of women who inherit a harmful BRCA2 mutation.

People who have the inherited mutation also tend to develop breast and ovarian cancers at younger ages than those who do not.

Should I be tested for these mutations?
The U.S. Preventive Services Task Force (USPSTF) recommends that primary care clinicians assess individuals’ personal and family history to determine if further evaluation through genetic counseling is warranted. Indications that may prompt someone to seek genetic counseling specific to inherited cancer risk assessment include a personal and/or family history of:

  • Ovarian cancer
  • Pancreatic cancer
  • Metastatic prostate cancer
  • Breast cancer diagnosed under age 45
  • Triple negative breast cancer diagnosed under age 60
  • Male breast cancer

While genetic testing is an extremely useful tool in determining if someone is at a higher risk for cancer, it is very complex and is not the only factor that influences cancer risk. While BRCA1/2 mutations make up a portion of inherited breast and ovarian cancer, there are also additional heredity cancer conditions that should be considered. For example, there is a gene known as PALB2 which causes an increased breast cancer risk similar to a BRCA2 mutation. Other genes that may influence breast cancer include but are not limited to ATM, CHEK2, CDH1, PTEN, TP53; each gene has unique cancer risks associated with mutations. A genetic counselor has expertise in assessing personal and family histories of cancer and will be able to determine what genes should be evaluated based on this information.  

Moffitt Cancer Center has six board-certified genetic counselors as part of its Genetic Risk Assessment, which provides genetic counseling and testing services for patients and their families, as well as individuals unaffected by cancer who wish to learn more about their cancer risk. If patients are found to have an inherited cancer risk, they can enter Moffitt’s GeneHome Clinic, which manages surveillance and recommends prevention measures.

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Sara Bondell Medical Science Writer More Articles


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