Women who have inherited a breast cancer mutation are at higher than average risk for developing breast cancer
Between 5 and 10% of all breast cancer cases occur in women with a genetic mutation. Not everyone with the gene will develop breast cancer, but those who inherit it will have a higher risk.
In 1990, researchers discovered the first breast cancer gene, BRCA1, which, when mutated, increases breast cancer risk. (BR is short for breast; CA is short for cancer.) In 1991, researchers discovered a second gene, called BRCA2. Approximately 50 to 90% of hereditary breast cancer cases are caused by mutations in the BRCA1 and BRCA2 genes (90% of cases from families with hereditary breast and/or ovarian cancer and 50% of cases from families with hereditary breast cancer).
It is estimated that about 13.2% of women (13 out of 100 women) in the general population will develop breast cancer in their lifetime. In contrast, it is estimated that about 55 to 65% of women with a BRCA1 mutation and 45% of women with a BRCA2 mutation will develop breast cancer by age 70.
Women who carry a mutation in the BRCA1 or BRCA2 gene also have an increased risk of developing ovarian cancer. It is estimated that about 1.7 percent (1 to 2 out of 100) of women will develop ovarian cancer in their lifetime. In contrast, it is estimated that about 16 to 60% (16 to 60 out of 100) of women who carry a BRCA1 or BRCA2 mutation will develop ovarian cancer.
Men who carry a BRCA1 or BRCA2 mutation are also susceptible to cancer; however, their risks remain less well understood. In women BRCA1 mutations carry the greatest risk; in men it is BRCA2. (Male BRCA1 carriers are also at increased risk of cancer.) The relative risk of developing cancer for male BRCA2 mutation carriers is high before age 65, mostly due to breast, prostate, and pancreatic cancer.
Males who carry BRCA 1mutations have a 1.2% lifetime risk while those who carry BRCA2 mutations have a 6.8% risk.
When a woman or man carries a genetic mutation that leads to an increased risk of breast cancer, there is a 50-50 chance the mutation will be passed on to her or his children. Whether or not the child goes on to develop breast cancer, she or he has a 50-50 chance of passing the mutation on to her or his own children.
In May 2008, the legislature passed and President Bush signed the Genetic Information Nondiscrimination Act (GINA). The law, which went into effect in 2009, makes it illegal for insurance companies to use genetic test results that indicate a person might be at greater risk for developing a certain disease as a reason to deny or cancel health insurance coverage or raise premiums. It also makes it illegal for an employer to use genetic tests results to make decisions on hiring, firing and compensation. As a result, more women may decide that BRCA testing is right for them.
Even with GINA in place, your BRCA test results could affect your eligibility for life insurance, disability insurance or long-term care insurance.
BRCA genetic testing usually costs between $1000 to $2000. Under the Affordable Care Act, both genetic testing and genetic counselors are covered for qualified individuals as a preventative service without cost-sharing
If you are going to be tested, do it through a genetic counselor. You can get a referral from your gynecologist or primary care doctor, bypassing a genetic counselor but this approach is not recommended. First of all, it may not be appropriate for you to be tested, and given the tendency for family physicians to inappropriately refer patients for testing, you need to be doubly careful.
A genetic counselor can help you learn whether the test should be done, and if it is done, can help you interpret the results. To find such a counselor, you can check with a nearby medical school. You can also call 1-800-FOR CANCER or look at this website which lists genetic counselors for cancer geographically throughout the United States.