A woman’s risk of developing breast and/or ovarian cancer is greatly increased if she inherits a deleterious (harmful) mutation in the BRCA1 gene or the BRCA2 gene.
Men with these mutations also have an increased risk of breast cancer, and both men and women who have harmful BRCA1 or BRCA2 mutations may be at increased risk of additional types of cancer.
Genetic tests can check for BRCA1 and BRCA2 mutations in people with a family history of cancer that suggests the possible presence of a harmful mutation in one of these genes.
If a harmful BRCA1 or BRCA2 mutation is found, several options are available to help a person manage their cancer risk.
What does a positive BRCA1 or BRCA2 genetic test result mean?
BRCA1 and BRCA2 gene mutation testing can give several possible results: a positive result, a negative result, or an ambiguous or uncertain result.
A positive test result indicates that a person has inherited a known harmful mutation in BRCA1 or BRCA2 and, therefore, has an increased risk of developing certain cancers. However, a positive test result cannot tell whether an individual will actually develop cancer or when. Many women who inherit a harmful BRCA1 or BRCA2 mutation will never develop breast or ovarian cancer.
A positive genetic test result may also have important health and social implications for family members (see Question 15), including future generations. Unlike most other medical tests, genetic tests can reveal information not only about the person being tested but also about that person’s relatives:
Both men and women who inherit harmful BRCA1 or BRCA2 mutations, whether or not they develop cancer themselves, may pass the mutations on to their sons and daughters. Each child has a 50 percent chance of inheriting a parent’s mutation.
If a person learns that he or she has inherited a harmful BRCA1 or BRCA2 mutation, this will mean that each of his or her siblings has a 50 percent chance of having inherited the mutation as well.