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There are two categories of risk factors for breast cancer – those we have
control over (modifiable) and those we do not (non-modifiable factors).
Beyond Your Control…
Gender: Women are much more likely to develop breast cancer. Men account for
only 1%-2% of all cases. Early menstruation (beginning your periods before age
12) increases your risk, while an early menopause reduces your risk.
Age: The risk increases as you age, particularly once you have gone through
menopause (over 75% of new cases occur in women over age 50). The incidence of
breast cancer in younger women is increasing and women in their 20s and 30s are
being diagnosed.
Genetics: If you inherited a genetic mutation such as BRCA1 or BRCA2, your risk
of developing breast cancer may be as high as 80%. But keep this in mind; only
about 5% of all breast cancer patients have one or more identifiable genetic
risk factors.
Race: White women have a higher risk of developing breast cancer than
African-American, Hispanic, Asian, or Native American women. (African-American
women, however, have a higher mortality rate compared to any other race.)
Family History: Having a first degree relative (mother, daughter, or sister)
that has been diagnosed with breast cancer increases your risk. If that
first-degree relative developed breast cancer before menopause or in both
breasts, your risk is even higher.
Personal History: If you have had breast cancer in the past, your risk is
increased. A history of benign (non-malignant) breast disease also increases
your risk.
The Good News…
Other risk factors are within your control including:
Smoking: Quitting smoking will decrease your risk.
Alcohol: High alcohol intake is associated with an increased risk of breast
cancer.
Radiation Exposure: Being exposed to high levels of radiation increases your
risk. This would apply to accidental exposure (the risk was found, for example,
in survivors of the atomic bomb explosions in Japan after World War II) or
high-dose radiation therapy (in the chest area) for treatment of cancers, such
as Hodgkin’s Disease. Note: exposure to “normal” x-rays (and mammograms) has not
been shown to increase the risk of breast cancer.
Lifestyle: Decreased physical activity, obesity, and a high-fat diet have been
linked to breast cancer in some studies, but no direct evidence has yet been
found that any of these cause breast cancer.
A Special Note: Hormone Replacement Therapy
Controversy surrounds the possible link between breast cancer and hormone
replacement therapy (HRT).
HRT, in the form of estrogen replacement (ERT), has been prescribed since the
1940s to treat the unpleasant side effects that menopause causes in some women.
It was widely promoted as a way to maintain woman’s youth because it treated
those nasty hot flashes and prevented vaginal dryness. It was believed to reduce
a woman’s risk of heart attack, osteoporosis, and other diseases that tended to
occur as women aged.
The first problem occurred when it was discovered that the incidence of cancer
of the uterus was higher in women taking estrogen. The answer to this was to add
progesterone if the woman still had her uterus.
In the 1990s, the results of the HERS trials (Heart and Estrogen/Progestin
Replacement Study) found that women on HRT had an increased risk for heart
attack their first year on HRT.
In 2002, a follow-up study (HERS II) confirmed those findings and also found an
increased risk of gall bladder disease.
Meanwhile, in 1993, the Women’s Health Initiative (WHI) study began to study the
long-term effects of estrogen/progestin therapy (HRT) on postmenopausal women
and estrogen therapy alone (ERT) on women who no longer had their uterus. Over
27,000 women, ages 50-79 were participating in the trials, some getting the
hormone therapy, others getting a placebo. In 2000 and 2001, it was announced
that the incidence of heart disease, stroke, and blood clots was higher in the
women taking the hormone replacement.
In 2002, the part of the WHI trial studying combination therapy was halted
because the researchers had determined that the women taking the HRT had a
slightly higher rate of heart disease, stroke, and blood clots…and breast
cancer. They also believed that these risks outweighed the benefits of HRT shown
in the study …lower rates of osteoporosis/bone fractures and colon cancer.
This year, the estrogen-only part of the WHI trial was also stopped prematurely.
Researchers had found that ERT did not prevent heart disease and seemed to
increase the risk of stroke, just like HRT.
Now What?
The HERS and WHI trials studied the effects on healthy, postmenopausal women
taking hormone replacement over a long period of time. The decision whether or
not to take HRT needs to be done on a case-by-case basis after a full discussion
between a woman and her doctor. The trend now appears to be a short-term course
of HRT for those women who are experiencing severe menopausal symptoms.
Breast Cancer and HRT
In 1997, the HABITS (Hormonal replacement therapy After Breast cancer – Is It
Safe?) trial began enrolling patients in Sweden. The study’s focus was to assess
the effects of a two-year program of HRT in women that had a history of breast
cancer.
In the end of 2003, this study too was halted prematurely after enrolling only
345 women. They stopped enrolling new patients and the women already in the
study were told to STOP taking their HRT medication. In looking at the data they
had already gathered, the researchers had found that 26 of the 174 women taking
the HRT had another occurrence of breast cancer compared to only 7 of the 171
women that were not on HRT.
Source :
http://www.breastcancer.about.com/od/riskfactors/a/rf01_2.htm