Scientists at the Baylor College of Medicine in Houston,
Texas have discovered that the protein kinase ATM (ataxia
telangiectasia) works with the BRCA1 tumor suppressor protein to
repair cellular DNA damage. Though the study needs further
confirmation, researchers believe that the link between the two
proteins may explain why women with a defect in the ATM protein
develop breast cancer more frequently than women with BRCA1
mutations alone. Women with mutated BRCA1 genes currently account
for 5% of all breast cancer cases.
The new study reveals that BRCA1 may rely on the ATM protein
to repair some types of cell damage. When DNA damage occurs in
cells, BRCA1 helps the body repair those cells-a process that may
prevent tumor development. However, BRCA1 cannot begin the process
of repairing cells when the damage is caused by some types of
radiation
therapies
. In
this case, BRCA1 must rely on the ATM protein to initiate the
repairs. ATM is important in recognizing when chromosomes are
broken, said Dr. Elledge.
In 1994, researchers discovered that women with mutated BRCA1
or BRCA2 genes have an increased risk of developing breast and
ovarian cancer . Dr. Sandhya Pruthi, MD, a
Breast Health Specialist at Mayo’s breast clinic, estimates that 20%
of women who carry BRCA1 mutations will develop breast cancer by age
forty, 51% by age fifty, and 87% by age sixty.
Women with malfunctioning BRCA1 or BRCA2 genes also have a 20% to 60% chance of
developing ovarian cancer, according to Dr. Pruthi. Additionally, BRCA1 mutations have
also been linked to a higher lifetime risk of colon and prostate cancer, while BRCA2
mutations may raise lifetime risk of these and possibly other cancers.(1) Both men and women may inherit BRCA1 and BRCA2 gene
mutations. 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 fifty
- 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)
Source: Mayo Clinic HealthOasis
Women who have BRCA mutations are sometimes treated with the
drug tamoxifen or chemoprevention (the use
of anticancer drugs to prevent the development of breast cancer).
Occasionally, surgeons may perform
mastectomy on women with mutated BRCA genes, although many health care
professionals favor less invasive measures.
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