No Easy Answers for Breast Cancer Gene Testing

A genetic mutation can significantly increases a woman's risk of developing breast cancer and ovarian cancer. But does that mean everyone should be tested? A new direct-to-consumer advertising campaign in select markets in the United States urges women to be tested. However, some experts warn that the test is not appropriate for all women.

"While the test is a very easy thing to do--it's a simple blood test --the interpretation of the results can sometimes be very complicated,” said Mark Pearlman, M.D., vice chair and professor of obstetrics and gynecology at the University of Michigan (U-M) Medical School (Ann Arbor, USA).

In fact, experts estimate only 2% of the population should be tested for these mutations, which occur in BRCA1 or BRCA2 genes. Women who inherit a mutation in these genes face a higher lifetime risk of developing breast and ovarian cancer, and cancer is more likely to develop at an earlier age. Lifetime risk of breast cancer in these women jumps from 12.5% in the general population to approximately 60% in women with BRCA mutations. Lifetime ovarian cancer risk rises from 1.4% to 40% for those with the mutation.

But most breast and ovarian cancers are random, and are not linked to the BRCA genes. Fewer than 10% of all women with breast cancer carry one of the BRCA gene mutations, and about 15% of women with ovarian cancer carry one of the mutations. "It's very important that the right women seek out genetic testing for breast and ovarian cancer,” said Sofia Merajver, M.D., Ph.D., director of the Breast and Ovarian Risk Evaluation Program at the University of Michigan Comprehensive Cancer Center. "Cancer risk is more complex than a simple yes or no, and the test for genetic mutations is only part of the picture.”

Women who seek genetic testing should work with a genetic counselor and a physician who is specially trained to help people understand what their test results mean for their cancer risk--and what they can do to reduce that risk. "Working with a genetic counselor, somebody who understands genetics, is very important because a positive test has a plan that has to go with it. At the same time, a negative test doesn't always mean that person is no longer at risk. So getting the test results back without any other knowledge and without any other information is potentially dangerous,' Dr. Pearlman remarked.

Dr. Pearlman and Dr. Merajver work together at the U-M Comprehensive Cancer Center to manage women who are seeking or have undergone genetic testing for breast and ovarian cancer, educating women and their families through genetic counseling, and providing prevention, risk management, and coping strategies for women who test positive. "It's important to understand that getting the genetic test result is only a piece of the puzzle. It really takes a professional who understands genetics to help work with individual women and men to allow them to understand exactly what that piece of information means to them in terms of their risk, their loved ones' risks and what can then be done to help lower that risk,” Dr. Pearlman commented.

For women who do test positive for a mutation, Dr. Pearlman's clinic helps them decide what to do about it. Options include getting mammograms at a younger age or more frequently, using breast magnetic resonance imaging (MRI), taking medication to reduce risk, or making lifestyle changes. Women who are finished with childbearing typically have their ovaries removed, and women may also choose to have their breasts removed to limit their risk.

Doctors recommend genetic testing for those who have: high numbers of family members with cancer diagnoses throughout several generations, either maternal or paternal; family member diagnosed with cancer before age 50; family members who have been diagnosed with multiple cancers (for example, breast and ovarian); and male breast cancers, or clusters of other cancers such as colon, prostate, stomach, or pancreatic.

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University of Michigan Medical School