Here’s some encouraging news for women whose family members carry the BRCA gene mutations that increase the risk of breast cancer: if you don’t have the mutations yourself, your risk of developing the disease isn’t significantly increased.
“This new study gives reassurance to non-carriers that they do not have an increased risk,” said Dr. Allison Kurian, one of the study’s authors and assistant professor of medicine and health research and policy at the Stanford University School of Medicine, in a statement.
The genetic mutations, known as BRCA1 and BRCA2, can increase a woman’s risk of developing breast cancer five-fold. According to the National Cancer Institute, 12% of women in the general population will develop breast cancer in her lifetime, compared with 60% of women who have inherited BRCA1 or BRCA2. The mutations also raise women’s lifetime risk of ovarian cancer, from about 1.4% to 15%-40%.
In 2007, a study found that women who didn’t have the mutations, but had first-degree relatives who did, were at a two- to five-times increased risk of breast cancer, compared with the general population. Those results suggested that non-carriers of the gene changes should be screened as if they were at high risk, and prompted many women to consider preventive measures like frequent biopsy of breast lumps and prophylactic mastectomy.
But the new study counters those findings, concluding that the risk of breast cancer in women from BRCA families, who do not carry the mutations themselves, are no higher than that of women in families with other types of breast cancer. The study involved more than 3,000 families with breast cancer, including nearly 300 who had the BRCA1 or BRCA2 mutations.
The researchers analyzed rates of the disease among first-degree relatives of patients with breast cancer — both patients with a BRCA mutation and those without. This comparison addressed what one of the study authors characterized as a “flaw” of the 2007 study, in an interview with HealthDay. The older study compared relatives of BRCA carriers against the general population, not against women in families with other types of breast cancer.
According to the American Cancer Society, having one first-degree relative, such as a mother, sister or daughter, with breast cancer doubles a woman’s risk of getting it. Having two close relatives increases the risk about threefold.
The new findings suggest that women in families with BRCA carriers don’t have to screen themselves for breast cancer more often than most women in the population do, with regular mammograms, as long as they don’t have other risk factors.
They may also want to take advantage of emerging genetic testing to determine whether they are at higher risk of developing the disease. “Genetic testing will give women a clearer indication of their real risk level and hence clarify what they could or should not do to reduce their risks of developing breast cancer,” said John Hopper, another of the study’s authors from University of Melbourne, in a statement. Those results would generate a more precise risk profile for that particular patient.
In the meantime, women can rest assured that simply having relatives with the BRCA mutations doesn’t necessarily put them at higher risk of developing breast cancer.
The study was published online by the Journal of Clinical Oncology.