Are you at risk of breast or ovarian cancer? Five to 10 percent of these cancers are caused by inherited mutations (errors) in two genes: BRCA1 and BRCA2 (breast cancer susceptibility genes 1 and 2). They are tumor suppressor genes, which help prevent uncontrolled cell growth.
According to the Genetic Science Learning Center at the University of Utah in Salt Lake City, about 60 percent of women who inherit either gene mutation will develop breast cancer by age 50; 80 percent will develop cancer by age 70. Women of eastern European Jewish (Ashkenazi) descent are significantly more likely to have a BRCA mutation.
A BRCA mutation does not mean that an individual will develop cancer, only that her risk is higher than someone who doesn't have this mutation. According to a small study from MD Anderson Cancer Center, breast cancer patients with BRCA mutations also developed breast cancer almost eight years earlier, on average, than women who don't have the mutation. The researchers say lifestyle and environmental factors may also play a role.
In a review of studies published between 1966 and 2004, the United States Preventive Task Force (USPTF) found clinically significant mutations in genes that affect breast cancer; 1 in 300 to 500 people in the general population. The USPTF recommends physicians refer women with a strong family history of breast or ovarian cancer for genetic counseling and evaluation, but does not recommend genetic screening for the general population.
A blood test will reveal whether you have a BRCA mutation. If you do, there are several options to help lower your risk of developing breast or ovarian cancers:
Preventive (prophylactic) surgery: The USPTF found fair evidence that removing both breasts (prophylactic bilateral mastectomy) reduces breast cancer risk by 85 percent. Removing the ovaries reduces ovarian cancer risk by 85 percent, and breast cancer risk by 53 percent.
Chemoprevention: Oncologists may use the drug tamoxifen to help protect against breast cancer.
Surveillance: Women who opt not to undergo surgery or preventive chemotherapy may choose regular screening to catch potential tumors earlier, when they are easier to treat.
However, note that the USPTF says there is insufficient evidence to determine the benefits of chemoprevention or intensive screening in improving health outcomes.
There is good news, however: the National Cancer Institute reports there is strong evidence that BRCA 1 and BRCA 2 gene mutation carriers with ovarian cancer are more likely to survive for five years after diagnosis than ovarian cancer patients who don't have these mutations. Researchers suspect this difference may be due to a better response to certain types of chemotherapy.
Rajiv V. Datta, MD, FRCS, FACS, FICS, reviewed this article.
Sources:
National Cancer Institute. "BRCA1 and BRCA2: Cancer Risk and Genetic Testing." Web. 29 May 2009. Page accessed 11 July 2013. http://www.cancer.gov/cancertopics/factsheet/Risk/BRCA
National Cancer Institute. "Women with BRCA1 and BRCA2 Mutations Survive Ovarian Cancer at Higher Rates Than Those Without Mutations."NCI News Note. Web. 24 January 2012. Page accessed 11 July 2013. http://www.cancer.gov/newscenter/newsfromnci/2012/BRCAmutationsOvarianNewsNote
Chustecka, Zosia. "Breast Cancer Developing Earlier in BRCA Generations." Medscape Medical News. Web. 12 Sept. 2011. Page accessed 11 July 2013. http://www.medscape.com/viewarticle/749487
Kolor, Katherine, PhD, CGC. "Hereditary Breast and Ovarian Cancer: BRCA and Your Patient." Medscape Medical News. Web. 10 October 2011. Page accessed 11 July 2013. http://www.medscape.com/viewarticle/749018
Genetic Science Learning Center. "Breast Cancer and Ovarian Cancer." University of Utah. Web. Page accessed 11 July 2013. http://learn.genetics.utah.edu/content/disorders/whataregd/brca/
