Testing for breast cancer mutations: Not for everyone
Too many average-risk women and too few high-risk women receive genetic counseling and testing for hereditary breast and ovarian cancers, research shows.
Experts at The University of Texas MD Anderson Cancer Center share advice to help patients and their doctors better evaluate family history and make more sound decisions about who should be tested.
"If you find out you’re the right candidate for genetic testing, one benefit of learning you have a mutation is that you and your doctor can work together to monitor and address your cancer risks," said Karen Lu, M.D., co-medical director of the Clinical Cancer Genetics program at MD Anderson.
"This can help prevent cancer or find it early, when it’s most treatable."
Women with BRCA1 or BRCA2 gene mutations are much more likely to get breast and ovarian cancers. Men with these mutations face an increased risk of breast cancer and possibly pancreatic and early-onset prostate cancers.
Focus on close blood relatives
But, only about 5 to 10% of cancer cases are due to an inherited cause. So, the chances that the disease "runs in the family" are slim, even if several family members have had cancer.
Before jumping to conclusions, Lu suggests focusing on first-degree blood relatives (parents, siblings, children) and second-degree relatives (grandparents, aunts, uncles, nieces, nephews). Women are twice as likely to develop breast cancer if one or more of these relatives have had the disease. Breast cancer risk is even higher if the disease has appeared in multiple generations on the same side of the family.
"For example, breast cancer probably doesn’t run in the family if your mother’s sister and father’s sister had breast cancer," Lu said.
Size up these relatives’ personal cancer histories.
Testing for BRCA mutations may be appropriate if one or more close blood relatives were diagnosed with:
- the same type of cancer,
- a BRCA1 or BRCA2 mutation,
- breast or ovarian cancer before age 50,
- both breast and ovarian cancer, or
- male breast cancer
The chances for a BRCA mutation is even higher for people of Ashkenazi (Eastern European) Jewish descent with one or more relatives who fit this description.
Speak with a genetic counselor
If one or more close blood relatives fit these criteria, ask a doctor for a genetic counseling referral. A genetic counselor can discuss the risks and benefits of genetic testing.
If genetic testing is appropriate, the best person to test is usually the person with cancer. “After we identify the mutation that caused their cancer, we can test first-degree relatives — mother, sisters, daughters — to see if they also carry it,” Lu said.
Carefully weigh testing’s pros and cons
It’s also important to consider family members’ feelings. That’s because the test results may forecast their cancer risks as well.
"No matter what you decide, remember that finding out you have a gene mutation doesn’t mean you’ll definitely get cancer," Lu said. "And, learning you don’t have a gene mutation doesn’t guarantee that you won’t get cancer."
For more information on genetic testing and cancer risk, click here.