Which Women Should Be Tested for Breast Cancer Genes


2017-02-17 14:51

Some breast cancers that cluster in families are associated with inherited mutations in certain genes, such as BRCA1 or BRCA2. Should you be tested?

Breast cancer is the second most commonly diagnosed cancer in women. (Only skin cancer is more common.) About one in eight women in the United States will develop invasive breast cancer in her lifetime.

Most cases of breast cancer are not caused by inherited genetic factors. Only about 5-10 percent of all breast cancers diagnosed in the U.S. are due to inherited gene mutations known to increase risk. The gene best known for increasing risk is the BRCA gene.

There are actually two BRCA genes. BRCA1 carriers have a 55-65 percent chance of developing breast cancer by age 70. Women who have a BRCA1 mutation also have an increased risk of their breast cancer being “triple negative.” BRCA2 carriers have about a 45 percent chance of developing breast cancer by age 70

Should you be tested for BRCA mutation?

Like most gene mutations, BRCA 1 and BRCA 2 mutations are rare in the general US population – between 1 and 400 and 1 in 800 people have this mutation. However, the prevalence of having a mutation varies by ethnic group. For example, among Ashkenazi Jewish people, about 1 in 40 carry the BRCA1/2 mutation.

Doctors feel today that not enough high-risk women are receiving proper genetic testing when it comes to breast cancer risk. In a recent study, about 56% of high risk women state they did not receive a recommendation from their physician to check for BRCA mutations (which also would determine those at greater risk for ovarian cancer as well as breast cancer).

“I think it’s very concerning,” says study author Dr. Allison Kurian of Stanford University’s School of Medicine. Genetic testing (when warranted) can help determine a woman’s risk of future cancer and may help guide the best type of treatment in those who ultimately have breast or ovarian cancer.

Examples of women who should consider testing include women who have a first-degree relative with the disease, especially if younger than age 50.

"It used to be this testing was very expensive, costing around $4,000," Kurian said. But today, even if not covered by insurance, women can usually get the tests for about $250 to $500.

The study was published Feb. 7 in the Journal of the American Medical Association, and was funded by the U.S. National Institutes of Health.

Photo Credit: By Vegasjon - Own work, CC BY-SA 4.0, via Wikimedia Commons