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Preventing
breast cancer in BRCA-positive women
Breast Cancer Prevention
Measures:
- Increased screening
- Chemoprevention: tamoxifen
- Prophylactic mastectomy
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Women who test positive for BRCA1
or BRCA2 genetic mutations are at higher risk of developing breast cancer and may wish to
consider preventive measures. The Mayo Clinic suggests that women at increased cancer risk
limit alcohol consumption and exercise regularly. Additionally, increased breast screening
helps to detect breast cancer at an early stage (when it is more easily treatable).
The American Cancer Society suggests
the following guidelines to help detect breast cancer early:
- Women 20 years of age and older should
perform breast self-examination (BSE) every month.
- Women 20-39 should have a physical examination of the breast (CBE or clinical
breast exam) at least every three years, performed by health care professional such as a
physician, physician assistant, nurse, or nurse practitioner. CBE may often be received in
the same appointment as a Pap smear. Women 20-39 should also perform monthly BSE.
- Women 40 and older should have a
physical examination of the breast (CBE or clinical breast exam) every year. CBE should be
performed by a health care professional such as a physician, physician assistant, nurse,
or nurse practitioner. CBE can often be performed in the same visit as a mammogram.
Monthly BSE should also be performed.
- Women 40 years of age and older should
have a screening mammogram every year in addition to annual
CBE and monthly BSE.
Women at high
risk of developing breast cancer (in consultation with her physician) may begin
screening mammography earlier age 40. Some experts suggest beginning screening ten years
prior to the age at which a close relative (mother, sister) was diagnosed with breast
cancer.
Click
here for more information on the early detection of breast cancer.
"Chemoprevention" (the use of
drugs, chemicals, vitamins, or minerals to treat breast cancer) is another option for
women at increased risk of developing breast cancer. One type of chemoprevention involves
the anti-cancer drug, tamoxifen. Tamoxifen has been used for twenty
years to treat advanced breast cancer. More recently, tamoxifen has been used to treat
early-stage breast cancer and to lower the risk of breast cancer
in women who are at high risk for the disease.
In its first major breast cancer
prevention trial (BCPT) from April 1992 to 1998, researchers for the National Surgical
Adjuvant Breast and Bowel Project (NSABP) found a 49% decrease in the incidence of
invasive breast cancer in women at increased risk for the disease who took tamoxifen
therapy in comparison to those who did not receive the drug and received a placebo (an
inactive pill) instead. The study showed that women taking tamoxifen also had fewer
diagnoses of noninvasive breast cancer, such as ductal carcinoma in
situ (DCIS). Click here for more information on the
NSABP tamoxifen trials.
Some women at high risk of developing
breast cancer may choose to have prophylactic mastectomy
(preventive removal of the breasts). A recent study published in the Journal of
Medicine revealed that prophylactic mastectomy reduced the risk of breast cancer by
90% in women at high risk for the disease. (Prophylactic mastectomy cannot reduce breast
cancer risk by 100% because it is not possible to remove all of the breast tissue). The
mortality rate from breast cancer was also reduced by 80% in the study.
Researchers are still not certain how
women will be affected by prophylactic mastectomy, though. Preventive surgery may increase
life expectancy in women with aggressive tumors. However, other women with BRCA1 or BRCA2
mutations never develop breast cancer and thus do not benefit from prophylactic
mastectomy. Less invasive procedures (such as lumpectomy) may
also be performed to treat breast cancer without having to remove the breast(s).
Though medical experts still do not
recommend prophylactic mastectomy, the following women are candidates for the procedure:
- Mutated BRCA1 or BRCA2 genes
- Previous cancer in one breast
- Strong family history of breast cancer
(mother or sister had breast cancer)
- Biopsy revealing lobular
carcinoma in situ (LCIS)
Note: Women who do not have any of the
above conditions should normally not consider having prophylactic mastectomy.
HER2 (or
HER2/neu)
HER2 (human epidermal growth factor receptor 2) is another
gene found on the surface of cells that plays a key role in regulating cell growth. When
the HER2 gene is altered, extra HER2 receptors may be produced. This over-expression of
HER2 causes increased cell growth and reproduction, often resulting in more aggressive
tumor cells.
HER2 protein over-expression affects
25% to 30% of breast cancer patients. Women with HER2 over-expression may not be as
responsive to standard breast cancer treatments, including certain regimens of
chemotherapy.
The United States Food and Drug
Administration (FDA) recently approved the drug Herceptin (generic name
Trastuzumab) for use in breast cancer patients whose cancer has metastasized (spread)
beyond the breast and underarm lymph nodes. Herceptin has been shown to slow the growth
and spread of cancerous tumors in a number of clinical trials. In some cases, cancerous
tumors have completely disappeared in patients taking Herceptin. Presently, only women who
are HER2 positive (and have metastasized breast cancer) are candidates for treatment with
herceptin. Click here for more information on Herceptin and HER2.
p53 Tumor
Suppressor
Little is known about the p53 tumor suppressor except that, when mutated, the p53 gene also increases
a woman's risk of developing breast cancer. A recent study published in the conducted by Dr. Ayman Linjawi
of the Royal Victoria Hospital in Montreal, Quebec, Canada reveals that women with early-stage breast cancer
who test positive for the mutated p53 tumor suppressor tend to have a poorer breast cancer prognosis than
women who do not carry the mutated p53. Dr. Linjawi and colleagues found that the Stage I breast cancer
patients with the mutant p53 had an average survival rate of 74% after five years compared with a survival
rate of 83% who did not have the mutant p53. p53 mutation testing is available to high-risk women at
specialized centers. However, according to the American Cancer Society, this testing has not been shown to
be helpful in determining current patients' treatment at this point. Further research on p53 genetic testing
is needed to determine whether it may one day have value in helping physicians choose a breast cancer
patient's best course of treatment.
Additional
Resources and References
Updated: June 29, 2008
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