Simply being a woman is the main risk factor for developing
breast cancer. Women's breast cells are constantly exposed to the
growth-promoting effects of the female hormones
estrogen and progesterone, thus making breast
cancer much more common in women than men.
Men can develop breast cancer, but this
disease is about 100 times more common among women than men.
Age
As a woman ages, her risk of breast cancer also
increases, much like many other
diseases. If you live to age 90, your average risk of
getting breast cancer over your lifetime is
1 in 7, but each 20 or so years of your
life is associated with
a different level of risk.
About 77% of women with breast cancer are over age 50
at the time of diagnosis. Three quarters of women with
breast cancer are over age 50 at the time of diagnosis.
Women between the ages of 20 and 29 account for
only 0.3% of breast cancer cases.
|
A Woman's Chances of Breast Cancer Increases With Age
|
| From age 30 to age 39
|
0.44% (1 in 227)
|
| From age 40 to age 49
|
1.49% (1 in 67)
|
| From age 50 to age 59
|
2.79% (1 in 36)
|
| From age 60 to age 70
|
3.38% (1 in 26)
|
Source: National Cancer Institute, www.cancer.gov, 2004.
The 1 in 7 statistic comes from averaging all
the different risk levels. So the overall risk
will always be higher than the risk associated
with any one age bracket.
Personal History of Breast Cancer
Women who have had breast cancer in one breast
are three to four times as likely to develop
breast cancer in the opposite breast than
women who have never had the disease.
This risk might be low or high,
depending on the first diagnosis.
Family History
If a woman's blood-related
relatives on either her mother or father's side
of the family have had breast cancer, then she is
at increased risk for the disease.
Having a first-degree
relative (mother, sister, daughter) with breast
cancer can double a woman's risk. However, other
factors play a role in this risk. For example,
if your grandmother was diagnosed with
breast cancer at age 75, this may not increase your
risk of the disease. Your grandmother was most likely
just 1 of the 13 women who gets breast cancer between
the ages of 60 and 79.
The risk of developing breast cancer is increased if:
 |
|
 |
|
Two or more relatives with breast or ovarian cancer |
|
|
|
Breast cancer occurs before age 50 in a relative (mother,
sister, grandmother or aunt) on either side of the family
|
|
|
|
The risk is higher if the mother or sister has a history of
breast cancer
|
|
|
|
Relatives with both breast and ovarian cancer |
|
|
|
One or more relatives with two cancers
(breast and ovarian, or two different breast cancers) |
|
|
|
A male relative (or relatives) with breast cancer |
|
|
|
A family history of breast or ovarian cancer and
Ashkenazi Jewish heritage
|
|
|
|
A family history includes a history of diseases associated with hereditary breast
cancer such as Li-Fraumeni or Cowdens Syndromes
|
Having 1 first-degree relative (mother, sister, or daughter) with
breast cancer approximately doubles a woman's risk.
Having 2, first-degree relatives increases her risk 5-fold.
Although the exact risk is not known, women
with a family history of breast cancer in a father or
brother also have an increased risk of breast cancer.
Altogether, about 20% to 30% of women with breast cancer
have a family member with this disease.
Genetics
Changes (or mutations) of certain genes may
cause some cells to become cancerous. Recent
studies have shown that up to 10% of breast
cancer cases are hereditary. To date, most inherited cases of
breast cancer have been associated with two genes: BRCA1,
which stands for BReast CAncer gene one, and BRCA2, or
BReast CAncer gene two. The function of these genes is to
keep breast cells growing normally and to prevent any cancer
cell growth. But when these genes contain abnormalities, or
mutations, they are associated with an increased breast cancer
risk. Abnormal BRCA1 and BRCA2 genes may account for up
to 10% of all breast cancers.
Women diagnosed with breast cancer who have an abnormal BRCA1 or BRCA2 gene
often have a family history of breast cancer, ovarian
cancer, or both. There are also women with a strong
family history of breast cancer who might have another
kind of genetic abnormality that's not yet been identified.
But it's also important to remember that
most women with
breast cancer have no significant family history of the disease.
Breast Density
Past research has shown that women
with "dense" breasts, which contain more glandular
and connective tissue, are more likely to be
diagnosed with breast cancer than women whose
breasts are less dense (mainly made up of fat tissue).
Breast cancer itself is dense and starts from glandular
tissue. Estrogen makes breast tissue more dense. So the
connection between breast density and breast cancer may
be related to higher levels of estrogen in the body. On
a mammogram, a cancer is harder to spot in dense tissue
than in fatty tissue. That's because the cancer looks a
lot like the glandular tissue around it.
Menstrual History
Women who begin menstruating at an early age (before age 12)
and those who reach menopause after age 55 have
an increased risk of breast cancer due to more
years of exposure to
estrogen and other hormones produced by
the ovaries. Keep in mind, we don't have any control over the amount
of estrogen that our ovaries produce over time.
Certain Breast Changes
Normal breast cells can
sometimes get overexcited and start to misbehave.
These changes can show up as a lump, thickness, or
calcifications on a mammogram. If a biopsy is done,
these changes can be seen under a microscope. When the
breast duct cells are overactive and appear unusual, the
pathology report may describe these findings with the term
atypical ductal hyperplasia. An uncontrolled growth of
breast cells in the lobule (the part of the breast that
makes milk) is called lobular carcinoma in situ or LCIS.
(Even though the word "carcinoma" is part of the term LCIS,
it is not considered a true cancer). These two types of
breast changes are associated with an increased risk of breast
cancer in the future. But these abnormalities
are not themselves cancerous.
Race
Breast cancer in the United States occurs more
often in white women than Latina, Asian, or African
American women. But in women 40 and younger, African
American women have the highest risk.
Radiation Therapy to the Chest Before Age 30
Women whose breast/chest area have been
exposed to radiation therapy before age 30
and particularly during childhood are at higher risk of developing
breast cancer, especially if radiation was used to
treat Hodgkin's disease. In general,
the younger the woman was exposed to
radiation, the greater the risk that she will develop breast cancer.
(This does NOT include radiation therapy to treat breast cancer.)
Late Pregnancy or No Pregnancy
Women who had their first
child after age 30 and women who never had a
full-term pregnancy are at a slightly higher risk for developing breast cancer
than those who gave birth earlier in life. A full-term pregnancy,
which stops your menstrual cycle for nine months, seems to offer
protection against breast cancer.
Exposure to DES (diethylstilbestrol)
DES is an estrogen-like
hormone used in the past to help women prevent miscarriage.
Daughters of women who used DES have an increased risk of
cancer of the vagina. This drug may also increase the risk
of breast cancer in women who used it and in their daughters
who were also exposed to it.
In Summary
If you weigh uncontrollable factors against those that CAN be
changed, you'll see that you can do a lot to lower your risk of
breast cancer. And while it's very hard to pin down specific
foods or chemicals that are firmly linked to a higher or lower
risk of breast cancer, researchers are working hard to find out
whatever they can about specific lifestyle and environmental
factors that may be within your control.
