Genetics and Prevention

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 BRCA 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 gene mutations are inherited from a parent.  

This is why most individuals with breast cancer gene 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% risk of inheriting it. 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.  

Our Cancer Genetics and Prevention Program offers blood and saliva tests to identify 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. There are several testing options which will be reviewed by your genetic counselor.  

Patients are counseled first 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.