Gene Tests for Breast Cancer: Do You Really Want and Need to Know?

To know or not to know -- that is the question many women struggle with when considering whether to be tested for the BRCA1 and BRCA2 gene mutations, an inherited genetic abnormality that greatly increases risks of developing both breast and ovarian cancers. The decision is further fraught because, if the result is positive, it raises questions about family members as well. Should sisters and daughters be tested, and how would that knowledge impact their lives?

In a very personal way, I understand the difficulties of those decisions. When genetic tests were first becoming available, long before my own breast cancer diagnosis six years ago, the women in my extended family grappled with the testing question. We are Ashkenazi Jews with a family history of breast and ovarian cancer — two factors that put us at a much higher risk for the gene mutation.

Even given those higher odds, our chance of having one of these genetic abnormalities was still very low — less than 1 percent of the general population[i] and 2.5 percent of Ashkenazi Jews have the BRCA1 or BRCA2 gene mutation. [ii] But it was another statistic that motivated us to decide in favor of testing. If we were among the unlucky ones with a gene mutation, our risk of developing breast and/or ovarian cancer would be extremely high. While the average risk of getting breast cancer is about 12 percent, the risk for women with a BRCA gene mutation can climb as high as almost 90 percent and the risk of ovarian cancer can jump to over 50 percent over a full lifetime. [iii]

Those are scary statistics, but they shouldn’t cause anyone to rush out and get a gene test. Whether testing is necessary or right for you is an extremely personal decision that should be made in consultation with your doctor and/or a genetic counselor. It’s important to at least consider testing if there are multiple cases of breast and ovarian cancer in your family, especially if diagnosed before the age of 50 and if a male relative has had breast cancer.

The Upside of Testing

There are significant benefits to knowing if you have a BRCA mutation. If a mutation is present, there are steps you can take for early detection, including more frequent clinical exams and screenings. Hormonal therapy medicine such as Nolvadex (tamoxifen) is one option that can significantly reduce the risk of hormone-receptor-positive breast cancer. Many women choose preventive surgeries; prophylactic double mastectomy decreases the risk of breast cancer by 90 percent [iv], while removing the ovaries and fallopian tubes lowers the risk of ovarian cancer by 80 percent and breast cancer by 50 percent. [v]

Knowing your BRCA status is also extremely helpful for selecting the most effective treatments if diagnosed with breast cancer. Knowledge of my own personal genetic makeup guided important treatment decisions after my breast cancer diagnosis.

Weighing the Pros and Cons

While knowledge is power, it can also be overwhelming. The results of genetic tests can require difficult and life-altering choices both for you and your family. Testing should only be done when you can actually use that information to take steps to reduce your cancer risk. When possible, the best approach is for a family member who’s had cancer to be the first to get tested. Depending on those results, other family members can then consider if testing is necessary. These decisions should not be made hastily. Take time to become well informed and fully weigh the pros and cons. Breastcancer.org is a great place to start the process — you’ll find information to help you understand what you need to know in the context of your personal situation so you can make the decision that’s best for you and your family.

[i] https://www.knowbrca.org/Provider/FNA/about-brca1-brca2-and-hereditary-breast-and-ovarian-cancers

[ii] Rainville, I, et al. Next-Generation Sequencing for Inherited Breast Cancer Risk: Counseling Through Complexity. Curr Oncology Rep. 16: 371. 2014.

[iii] Arindam, P, et al. The Breast Cancer Susceptibility Genes (BRCA) in Breast and Ovarian Cancers. Frontiers in Bioscience - Landmark. 19: 605-618. 2014.

[iv] Armstrong, A. Management of Women at High Risk of Breast Cancer. BMJ. 348:g2756. 2014.

[v] Rebbeck, T, et al. Meta-analysis of Risk Reduction Estimates Associated With Risk-Reducing Salpingo-oophorectomy in BRCA1 or BRCA2 Mutation Carriers. J Natl Cancer Inst. 101:80-87. 2009.