Breast Cancer: Risk Factors
What is a risk factor?
A risk factor is anything that may
increase your chance of having a disease. Risk factors for a certain type of cancer
might include smoking, diet, family history, or many other things. The exact cause
someone’s cancer may not be known. But risk factors can make it more likely for a
to have cancer.
Things you should know about risk
factors for cancer:
Risk factors can increase a
person’s risk, but they do not necessarily cause the disease.
Some people with 1 or more
risk factors never develop cancer. Other people can develop cancer and have no
Some risk factors are very
well known. But there is ongoing research about risk factors for many types of
Some risk factors, such as family
history, may not be in your control. But others may be things you can change. Knowing
the risk factors can help you make choices that might lower your risk. For example,
an unhealthy diet is a risk factor, you may choose to eat healthy foods. If excess
weight is a risk factor, your healthcare provider may check your weight or help you
Who is at risk for breast cancer?
Risk factors for breast cancer
Gender. Breast cancer occurs about 100 times more
often in women than in men.
Race or ethnicity. White women develop breast cancer
slightly more often than African-American women. But African-American women tend
to die of breast cancer more often. This may be partly due to the fact that
African-American women often have a more aggressive type of tumor. (Aggressive
tumors grow and spread quickly.) Why this happens is not known. The risk for
having breast cancer and dying from it is lower in women who are Hispanic, Native
American, or Asian.
Older age. Most women with invasive cancer are older
than age 55.
History of breast cancer. If you’ve had cancer in 1
breast, you’re at an increased risk of having it in the other breast or another
part of the same breast.
chest radiation for another cancer. If you’ve had
high-dose radiation to your chest, you have an increased chance of breast cancer.
The risk is even higher if it happened when you were a child or teen. It’s
important to remember that radiation therapy involves high doses of radiation. The
small doses used for breast cancer screening do not increase your risk.
Family history. Having a parent, sibling, or child
with breast cancer increases your risk.
Benign breast disease. Women with certain noncancer
(benign) breast conditions such as hyperplasia or atypical hyperplasia have an
increased risk of breast cancer. The only way to know if you have benign breast
disease and what kind it is by having a biopsy.
Lobular carcinoma in situ (LCIS). LCIS is a noninvasive
growth of abnormal cells in the lobules of the breasts (milk-producing glands). LCIS
is not considered cancer. But it increases the risk of getting breast cancer. LCIS
typically diagnosed from a biopsy that is done on the breast for another reason.
diethylstilbestrol) exposure. Women who took this medicine while pregnant
to lower the chance of miscarriage are at higher risk. Women whose mothers took
DES during pregnancy may also have a slightly higher risk.
Early menstrual periods. Women whose periods began
before age 12 have a slightly higher risk of breast cancer.
Late menopause. Women are at a slightly higher risk if
they began menopause after age 55.
Not giving birth to a child, or giving birth to your first
child after age 30.
These women have a slightly higher breast cancer
Dense breast tissue. Women whose breasts have larger
areas of dense tissue on mammograms are at increased risk for breast cancer.
Drinking alcohol. Breast cancer risk goes up if you
drink just 1 glass of wine, beer, or a mixed drink a day. The more you drink, the
higher your risk. Limit yourself to less than 1 drink per day.
Long-term use of estrogen and progestin medicines after
This is known as hormone replacement therapy (HRT). The
hormones are most often used together. The longer you’ve used HRT, the higher your
risk. If you stop taking the medicines, your risk should go back down to normal
after 5 years. If you decide to use HRT, use it at the lowest dose and for the
shortest time possible.
Excess weight, especially after menopause. This risk
factor is complex. Research shows conflicting results about the link between
weight and breast cancer. Overall, your risk of breast cancer is lower if you stay
at a healthy weight with a body mass index (BMI) below 25. If you’re overweight
and you get breast cancer, the excess weight also affects your chances of being
cured. And it affects your chances of the cancer coming back after treatment.
BRCA1 and BRCA2 genes. Certain inherited changes in
genes are another risk factor. Hereditary breast cancer accounts for about 1 in 20
to 1 in 10 breast cancer cases. BRCA1 and BRCA2 genes are the most common genes
linked to breast cancer. These are tumor suppressor genes that usually have the
job of controlling cell growth and cell death. When they’re changed, they don’t do
their job correctly, and cancer tumors may grow. Changes in these genes account
for most cases of hereditary breast cancer. They’re linked to other kinds of
cancer, especially ovarian cancer. In the U.S., BRCA changes are most common in
women of Ashkenazi Jewish ancestry.
There are other, less common genes
that can impact breast cancer risk.
What are your risk factors?
Talk with your healthcare provider
about your risk factors for breast cancer and what you can do about them. There are
different tools that can be used to help estimate your risk. These can help you to
up your own best prevention and screening plan.