Wed 12 Jun 2013
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A test for mutations in the BRCA1 gene helped inform actress Angelina Jolie's recent headline-making decision to undergo a double mastectomy to mitigate what doctors estimated to be an 87% risk of developing breast cancer. The test confirmed she has a mutated BRCA1 gene, one of two genes for which mutations are linked with hereditary breast and ovarian cancers.
While the purpose of BRCA1 or BRCA2 testing is to determine a person's risk of developing breast or ovarian cancer due to mutations in these genes, it is not useful for everyone. Only 0.2% of the Australian population carries a BRCA mutation, so testing is not recommended for the average person. Higher risk groups that should consider testing include those who have had breast cancer before the age of 50 or ovarian cancer at any age, those with family members who meet these criteria, males with breast cancer, and those who have a family history of BRCA1 or BRCA2 mutations. It is highly recommended that candidates for the test seek the advice of a genetic counsellor both before and after testing. (For more on the test, read the BRCA1 and BRCA2 article.)
When functioning normally, BRCA1 and BRCA2 are tumour suppressor genes that help prevent cancer by producing proteins that suppress abnormal cell growth. A person who inherits mutated copies of the BRCA genes can be at risk of uncontrolled cell growth and development of cancer. According to doctors, the preventive surgery reduced Jolie's breast cancer risk down to 5%.
Jolie announced her decision to have the double mastectomy in a May 14th op-ed article for the New York Times, citing her mother's untimely death from ovarian cancer at the age of 56 as a motivating factor. News then broke that Jolie will also have her ovaries removed because the BRCA1 test revealed that she has a 50% chance of developing ovarian cancer.
According to Breast Cancer Network Australia, each year 15,000 women will be diagnosed with breast cancer in 2013. Mutations in BRCA1 or BRCA2 are responsible for a small portion of these cases, estimated to be between 5% and 10%. Women with BRCA mutations have up to an 85% risk of developing breast cancer and a 30-50% risk of developing ovarian cancer. Individuals who test positive for a BRCA mutation can opt to have preventive surgery like Jolie or use risk-reducing medications such as tamoxifen and surveillance techniques like mammography.
While noting that sharing her experience was meant to raise awareness about options for prevention, Jolie recognized that such surgical intervention is not for everyone. People with a BRCA mutation should carefully consider options and discuss with their doctor and a genetic counsellor.