Breast Cancer Prevention (cont.)
What are the risk factors for developing breast cancer?
The most significant risk factors for breast cancer are gender and age. Men
can develop breast cancer, but women are 100 times more likely to develop breast
cancer than men. Breast cancer is 400 times more common in women who
are 50 years old as compared to those who are 20 years old.
Family history
Another important risk factor is having
first-degree relatives (mother, sister, or daughter) with breast cancer or male
relatives with prostate cancer.
The risk is especially higher if both the mother and sister have had breast
cancers, if the cancers in first-degree relatives occurred early in life (before
age 50), or if the cancers in these relatives were found in both breasts. Having
a male relative with breast cancer and having both relatives with breast and
ovarian cancers also increase a woman's risk of developing breast cancer.
Families with multiple members with other cancers may have a genetic defect
leading to a higher risk of breast cancer.
Women who have inherited defective BRCA1, BRCA2, p53, and DNA repair genes
have an increased risk of developing breast cancer, sometimes at early ages, as
discussed previously. But even in the absence of one of the known predisposing
genetic defects, a strong family history may signify an increased risk because
of genetic or environmental factors that are specific to that particular family.
For example, increased risk in families could be due to exposure
to similar environmental toxins in some cases.
Previous breast cancer
A woman with a history of breast cancer can develop a
recurrence of the same
breast cancer years later if the cancer cells had already spread to the lymph
nodes or other
parts of the body. A woman with previous breast cancer also has a three- to
fourfold greater chance of developing another breast cancer in the opposite
breast. In women who have been treated for breast cancer with breast
conservation therapy (BCT), recurrence of cancer within the treated breast may
also occur.
Other breast conditions
Even though most women with fibrocystic breasts and its related breast
symptoms do not have increased risk of developing breast cancer, the lumpy
texture and density of the breasts may hamper early cancer detection by
breast examination or by mammography. Sometimes, women with fibrocystic breast
changes have to undergo breast biopsies (obtaining small tissue samples from the
breast for examination under a microscope) to make certain that palpable lumps are not
cancerous.
Breast biopsies sometimes may reveal abnormal, though
not yet cancerous, cell changes (called atypical hyperplasia). Women with atypical hyperplasia of the
breast tissue have about a four- to fivefold enhanced likelihood of developing
breast cancer. Some other benign cell changes in breast tissue are also
associated with a slight increase (one and a half to two times normal) in risk. These are
termed hyperplasia of breast tissue without atypia, sclerosing adenosis,
fibroadenoma with complex features, and solitary papilloma.
The common benign breast tumor known as a fibroadenoma, unless it has unusual
features under the microscope, does not confer an increased cancer risk.
Breast cancer risks can be additive. For example, women who have first-degree
relatives with breast cancer and who also have atypical hyperplasia of the
breast tissue have a much higher risk of developing breast cancer than women
without these risk factors.
Radiation therapy
Women with a history of radiation therapy to the chest
area as treatment for another cancer (such as Hodgkin's disease or non-Hodgkin's lymphoma) have a
significantly increased risk for breast cancer, particularly if the radiation
treatment was received at a young age.
Hormonal factors
Women who started their menstrual periods
before age 12, those who have late menopause (after age 55), and those who had
their first pregnancy after age 30, or who have never had children have a mildly
increased risk of developing breast cancer (less than two times the normal
risk). Early onset of menses, late
arrival of menopause, and late or no pregnancies are all factors that increase a
woman's lifetime level of estrogen exposure.
Studies have confirmed that long-term use (several years
or more) of hormone therapy (HT) after menopause, particularly estrogens and
progesterone combined,
leads to an increase in risk for development of breast cancer. This risk appears
to return to normal if a woman has not used hormone therapy for five years or more.
Similarly, some studies show birth control pills cause a small increased risk of breast cancer, but this risk
also returns to normal after 10 years of nonuse. The decision whether to use hormone therapy or birth control pills involves weighing the risks versus the benefits and should be individualized after consulting one's doctor.
Lifestyle factors
Dietary factors such as high-fat diets and alcohol
consumption have also been implicated as factors that increase the risk for
breast cancer. Cigarette smoking, caffeine intake, antiperspirant use, and
stress do not appear to increase the risk of breast cancer. It is important to
remember that 75% of women who develop breast cancer have no
risk factors other than age. Thus, screening and early detection are important
to every woman regardless of the presence of risk factors.
Next: What is the importance of early breast cancer detection? »
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