We do not yet know exactly what causes breast cancer, but we do know that certain risk factors are linked to the disease. A risk factor is anything that increases a person’s chance of getting a disease such as cancer. Different cancers have different risk factors. Some risk factors, such as smoking, can be controlled. Others, like a person’s age or family history, can’t be changed. But having a risk factor, or even several, doesn’t mean that a person will get the disease.
Some women who have one or more risk factors never get breast cancer. And most women who do get breast cancer don’t have any risk factors. While all women are at risk for breast cancer, the factors listed below
can increase a woman’s chances of having the disease.
Risk Factors That You Cannot Change
Gender Simply being a woman is the main risk factor for breast cancer.
Age The chance of getting breast cancer goes up as a woman gets older.
About 8 out of 10 breast cancers are found in women over age 50.
Genetic risk factors About 1 case of breast cancer in 10 is linked to
changes (mutations) in certain genes. The most common gene changes are
those of the BRCA1 and BRCA2 genes. But other gene changes may raise
breast cancer risk as well.
Family history Breast cancer risk is higher among women whose close
blood relatives have this disease. The relatives can be from either the
mother’s or father’s side of the family. Having a mother, sister, or
daughter with breast cancer about doubles a woman’s risk.
Personal history of breast cancer A woman with cancer in one breast has
a greater chance of getting a new cancer in the other breast or in
another part of the same breast. This is different from the first cancer
coming back (recurrence).
Race White women are slightly more likely to get breast cancer than are
African-American women. But African-Americans are more likely to die of
this cancer. Asian, Hispanic, and American Indian women have a lower
risk of getting breast cancer.
Earlier breast biopsy Certain types of abnormal biopsy results can be
linked to a slightly higher risk of breast cancer.
Earlier radiation treatment Women who have had chest area radiation
treatment earlier in life have a greatly increased risk of breast cancer.
Menstrual periods
Women who began having periods early (before 12 years of age) or who
went through the change of life (menopause) after the age of 50 have a
small increased risk of breast cancer. The same is true for women who
have not had children, or who had their first child after they were 30
years old.
Treatment with DES In the 1940s through the 1960s some pregnant women
were given DES (diethylstilbestrol) because it was thought to lower
their chances of losing the baby. Recent studies have shown that these
women have a slightly increased risk of developing breast cancer.
Breast Cancer Risk and Lifestyles
Not having children Women who have had no children, or who had their
first child after age 30, have a slightly higher risk of breast cancer.
Birth control pills It is still not clear what part birth control pills
might play in breast cancer risk. Studies have found that women now
using birth control pills have a slightly greater risk of breast cancer.
Women who stopped using the pill more than 10 years ago do not seem to
have any increased risk. It’s a good idea to discuss the risks and
benefits of birth control pills with your doctor. Hormone replacement
therapy (HRT) It has become clear that long-term use (several years or
more) of combined HRT (estrogens together with progesterone) for relief
of menopause symptoms may slightly increase the risk of breast cancer as
well as the risk of heart disease, blood clots, and strokes. The breast
cancers are also found at a more advanced stage. As well, HRT seems to
reduce the effectiveness of mammograms. Five years after stopping HRT,
the breast cancer risk appears to drop back to normal. Estrogen alone
(ERT) does not seem to increase the risk of breast cancer as much, if at
all.
At this time, there appear to be few strong reasons to use HRT, other
than for temporary relief of menopausal symptoms. Because there are
other factors to think about, you should talk with your doctor about the
pros and cons of using HRT.
Breast feeding Some studies have shown that breastfeeding slightly
lowers breast cancer risk, especially if the breast feeding lasts 1½ to
2 years. This could be because breast feeding lowers a woman’s total
number of menstrual periods. Alcohol Use of alcohol is clearly linked to
a slightly increased risk of getting breast cancer. Women who have one
drink a day have a very small increased risk. Those who have 2 to 5
drinks daily have about 1½ times the risk of women who drink no alcohol.
The ACS suggests limiting the amount you drink, if you drink at all.
Diet Being overweight is linked to a higher risk of breast cancer,
especially for women after change of life and if the weight gain took
place during adulthood. Also, the risk seems to be higher if the extra
fat is in the waist area. But the link between weight and breast cancer
risk is complex and studies of fat in the diet as it relates to breast
cancer risk have often given conflicting results. Since diet and weight
have been shown to affect the risk of getting several other types of
cancer and heart disease, the ACS says it’s best to stay at a healthy
weight and limit your use of red meats, especially those high in fat or
processed.
Exercise Exercise and cancer is a fairly new area of research. Some
studies suggest that exercise in youth might give life-long protection
against breast cancer. A small amount of physical activity as an adult
may also lower breast cancer risk. More research is being done to
confirm these findings.
While a direct link between smoking and breast cancer has not been
found, smoking affects your overall health and increases the risk for
many other cancers, as well as heart disease. If you smoke, you should
make every attempt to quit.
Recent internet e-mail rumors have suggested that underarm
antiperspirants or underwire bras can cause breast cancer. There is no
evidence to support this idea.
Several studies show that induced abortions do not increase the risk of
breast cancer. Also, there is no evidence to show a direct link between
miscarriages and breast cancer.
Silicone breast implants can cause scar tissue to form in the breast.
But several studies have found that this does not increase breast cancer
risk. If you have breast implants, you might need a special x-ray
picture during mammography.
Right now, research does not clearly show a link between breast cancer
risk and pollutants such as pesticides. A great deal of research has
been reported and more is going on in this area.