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A new study finds that women who are diagnosed with breast cancer and receive genetic testing
to determine their risk of developing cancer in the opposite breast are more likely to choose
preventive treatment. Normally, women with breast cancer are given the option of genetic testing
after their breast cancer surgery to determine whether they carry mutations of certain genes that
put them at greater risk of developing breast cancer in the other breast. However, the current
study suggests that performing genetic testing prior to breast cancer surgery can help women make
informed decisions about preventive measures.
Women who test positive for genetic mutations of the
BRCA1 (breast cancer gene 1) or
BRCA2 (breast cancer gene 2) genes are at a higher than
average risk of developing breast cancer. Over a lifetime, women with BRCA mutations have a
50% to an 85% chance of developing breast cancer. However, only around 5% of breast cancer
cases are associated with BRCA gene mutations.
All women are born with BRCA genes. When functioning normally, BRCA1 and BRCA2 genes help repair
damage to DNA-a process that also prevents tumor development. In 1994, researchers
discovered that women who carry mutations of BRCA1 or BRCA2 are at higher risk of
developing both breast and ovarian cancer than women
who do not have these genetic mutations.
In the current study, Jeffrey N. Weitzel, M.D., of the City of Hope National Medical Center in
Duarte, California, and colleagues performed genetic testing on 32 women with breast cancer
prior to breast cancer surgery (mastectomy). Seven of the 32 women were found
to BRCA gene mutations, putting them at high risk of developing breast cancer again.
Knowing their genetic test results prior to mastectomy, all seven women opted for the preventive
removal of the opposite breast at the same time as their original mastectomy. Preventive, or
prophylactic, mastectomy, though controversial, has been shown to greatly reduce the
chances of developing breast cancer in the future.
Dr. Weitzel and his team conclude that knowledge of a genetic mutation prior to breast cancer
surgery influences women's decisions about preventive options. However, the researchers question
the feasibility of genetic testing prior to the original breast cancer treatment.
According to the Mayo Clinic, families that typically pass on BRCA defects have the following
characteristics:
- Breast cancer in two or more close relatives, such as a mother and two sisters
- Early onset of breast cancer in family members, often before age 50
- History of breast cancer in more than one generation
- Cancer in both breasts in one or more family members
- Frequent occurrence of ovarian cancer
- Eastern and Central European (Ashkenazi) Jewish ancestry, with a family history of breast and/or ovarian cancer (researchers have identified two types of BRCA1 mutations and one BRCA2 mutation that are especially prominent in this group)
Genetic testing is a controversial subject, and healthcare professionals recommend
seriously considering the consequences of knowing the test results before deciding
whether genetic testing is appropriate. Advantages to genetic testing include feelings
of relief, the opportunity to try new treatments or preventive measures targeted toward
BRCA mutation carriers, and taking more aggressive breast cancer preventive and/or
treatment options if test results are positive. Disadvantages to BRCA gene testing
include increased stress if the results are positive, telling family members that they
may also carry the mutations, and facing potential difficulties with insurance providers
if the testing is not conducted anonymously. Women who are considering genetic testing
for BRCA gene mutations are encouraged to discuss the decision with a genetic counselor
before undergoing testing.
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