What is Hereditary Breast and Ovarian Cancer?
One in eight (12 percent) of U.S. women 90 years or younger will develop breast cancer during her lifetime.
One in 70 (1.4 percent) will develop ovarian cancer.
The three greatest risk factors for both breast cancers and ovarian cancer are:
- Being female
- Increasing age
- Family history of breast and/or ovarian cancer
Most breast and ovarian cancers are not caused by an inherited genetic factor. But, 5-10 percent of all breast cancer is caused by a genetic change inherited (passed down) from a parent. Patients with hereditary cancer, and their family members, face additional cancer risks. Identifying those at risk and providing a cancer risk assessment is vital to provide the best care for all members of these families.
BRCA-1 and BRCA-2
BRCA-1 and BRCA-2 are two genes that we know are related to breast and ovarian cancer risk. Some changes (mutations) in these genes increase this risk.
Inherited mutations in genes other than BRCA-1 and BRCA-2 have been shown or are suspected to increase susceptibility for developing breast and other forms of cancer. Testing might be available for some of these mutations as well. A cancer risk assessment is vital in making sure appropriate genetic testing is offered.
Incidence of BRCA-1 or BRCA-2 Mutation
Most women do not have a mutation in the BRCA-1 or BRCA-2 gene. The National Cancer Institute has stated that some factors make it more likely that a person carries an inherited BRCA mutation. They include:
- A family history of (three or more) close blood relatives (sisters, daughters, mother, grandmothers, aunts, cousins) with breast cancer, ovarian cancer, or both.
- A family history of early onset (before 50 or before menopause) breast or ovarian cancer in one or more close blood relatives (sisters, daughters, mother, grandmothers, aunts).
- A family history of one or more close blood relatives (sisters, daughters, mother, grandmothers, aunts) with two or more primary tumors of the breast or bilateral breast cancer.
- A family history of one or more close male blood relatives (father, sons, brothers, uncles, grandfathers) who have developed breast cancer.
- Ashkenazi (Eastern European) Jewish ancestry and a family history of breast and/or ovarian cancer.
A full family history is needed when looking at a person's risk for breast / ovarian cancer. It is important to ask about mom AND dad's family history related to breast cancer.
Women or men who meet one or more of the above factor can contact their primary health provider for referral for genetic counseling and cancer risk assessment. At this assessment, they will discuss their risks for breast and / or ovarian cancer and whether BRCA testing is right for them.
BRCA-1 and BRCA-2 Test Results
The risks associated with mutations in BRCA-1 and BRCA-2 include a 50-85 percent risk for breast cancer and a 10-45 percent risk for developing ovarian cancer. This risk is much higher than the risk in the general population.
Information is limited on how other non-genetic factors influence the risks associated with these mutations. For people who have a BRCA mutation, choices to manage this may include: increased or more intensive monitoring, chemoprevention, or prophylactic surgery to remove at-risk organs. Screening must be started at a young age, most often between the ages of 20-25 years of age.
Though some of these options may reduce the risk for developing breast and / or ovarian cancer, no option totally gets rid of this risk.
Though the BRCA genes are the most common hereditary causes of breast and ovarian cancer, there are other genes that may also contribute to a family history of breast, ovarian or other cancers. Testing for these genes recently became available.