Most breast and ovarian cancer cases are not caused by hereditary predisposition. Approximately 10 percent of ovarian cancers and five to seven percent of breast cancers are hereditary. The majority of the hereditary cases result from mutations, or changes, in the BRCA1 or BRCA2 genes, which cause a condition known as Hereditary Breast and Ovarian Cancer Susceptibility syndrome (HBOCS). Other genes, many of which are unknown, may also cause hereditary cancers.
Gene mutations result from damage to the cell’s DNA. Mutations in the BRCA genes are believed to have occurred in the distant past and are not believed to occur spontaneously today. Therefore, it is expected that mutations in the BRCA genes are inherited from a parent. This is why most individuals with BRCA mutations will have a family history of premenopausal breast and/or ovarian cancer.
We inherit half of our genetic material from each of our parents. If a parent is a carrier of a gene mutation, there is a risk that the mutation could be passed on to each child. If a person is a carrier of a BRCA mutation, each child has a 50 percent risk of inheriting it.
Yes, mutations within the BRCA genes are especially common in the Ashkenazi Jewish population. Approximately 1 in 40 Eastern European Jewish individuals are expected to be carriers. Other groups, such as the Icelandic community, may also have an increased risk of carrying the mutation.
At Women & Infants, our Cancer Genetics and Prevention Program offers a blood test to identify any BRCA genetic mutations. Your genes function as your body’s instruction manual. They are made up of letters from the genetic alphabet. Normally, your body is able to “read” these genes in order to carry out the gene’s function. A mutation is essentially a “misspelling” within the gene code. The BRCA test reads the BRCA1 and BRCA2 genes to identify a change in the code such as a letter(s) that is missing or added. Sometimes there can be large rearrangements of genetic material within the gene that may require additional testing.
The BRCA test is not designed as a screen for the general population. The majority of breast and ovarian cancer is not hereditary, therefore, most families with breast or ovarian cancer will not carry a BRCA gene mutation. This test is appropriate for women with a personal and/or family history that includes:
The cancer family history does not need to be as strong if the family is of Ashkenazi Jewish decent since we know there is an increased BRCA carrier risk in this population.
Women who are found to carry a BRCA1 or BRCA2 mutation have a significantly elevated risk of breast and ovarian cancer. The lifetime risk of breast and ovarian cancer may be as high as 87 and 44 percent, respectively. There are medical management guidelines established for people who carry BRCA mutations. Options include:
It is important to remember that a positive test result does not mean the person will develop cancer, just that they are at a higher risk.
Yes, a negative test result does not eliminate the risk of breast and ovarian cancer. A woman’s risk will still depend on her family history and whether other family members have already tested positive for a mutation in a BRCA gene. All women must continue to receive the annual cancer screenings recommended for the general population, even after a negative test result. Test results are always discussed and interpreted for the patient, including individualized recommendations for cancer screening and risk reduction.
Yes, patients are counseled since the test results could have a major impact on their medical care and that of their family. It is important that the patient makes an informed decision about the blood test, so a risk assessment is performed before the testing is even discussed. The assessment helps the patient understand her chance of testing positive for a gene mutation. Patients who test positive for a mutation must decide how to manage their increased risk. In addition, a positive result means other family members may also have significantly increased cancer risks or greatly overestimate their cancer risk.
If a patient decides she does not want to learn her genetic status, medical management recommendations are made based on the family history of cancer and the patient’s predicted lifetime cancer risks. Patients with strong family histories of breast and ovarian cancer may still be urged to follow a screening regimen similar to that of a BRCA-positive patient.
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