The exact causes of breast cancer are not known. However, studies
show that the risk of breast cancer increases as a woman gets older.
This disease is very uncommon in women under the age of 35. Most
breast cancers occur in women over the age of 50, and the risk is
especially high for women over age 60. Also, breast cancer occurs
more often in white women than African American or Asian women.
Research has shown that the following conditions increase a woman's
chances of getting breast cancer:
- Personal history of breast cancer.
Women who have had breast cancer face an increased risk of getting
breast cancer in their other breast.
- Family history. A woman's risk for
developing breast cancer increases if her mother, sister, or
daughter had breast cancer, especially at a young age.
- Certain breast changes. Having a
atypical hyperplasia or lobular
carcinoma in situ (LCIS) may increase a woman's risk for
- Genetic alterations. Changes in
certain genes (BRCA1, BRCA2, and others) increase the risk of
breast cancer. In families in which many women have had the
disease, gene testing can sometimes show the presence of specific
genetic changes that increase the risk of breast cancer. Doctors
may suggest ways to try to delay or prevent breast cancer, or
to improve the detection of this disease in women who have these
changes in their genes. For more information about gene testing,
read the "Causes and Prevention" section under "The
Promise of Cancer Research."
Other factors associated with an increased risk
for breast cancer include:
- Estrogen . Evidence suggests that
the longer a woman is exposed to
estrogen (estrogen made by the body, taken as a drug, or
delivered by a patch), the more likely she is to develop breast
cancer. For example, the risk is somewhat increased among women
menstruation at an early age (before age 12), experienced
late (after age 55), never had children, or took hormone
replacement therapy for long periods of time. Each of these
factors increases the amount of time a woman's body is exposed
to estrogen. DES (diethylstilbestrol) is a synthetic form
of estrogen that was used between the early 1940s and 1971.
Women who took DES during pregnancy to prevent certain complications
are at a slightly higher risk for breast cancer. This does not
appear to be the case for their daughters who were exposed to
DES before birth. However, more studies are needed as these
daughters enter the age range when breast cancer is more common.
- Late childbearing. Women who
have their first child late (after about age 30) have a greater
chance of developing breast cancer than women who have a child
at a younger age.
- Breast density. Breasts that have
a high proportion of lobular and ductal tissue appear dense
mammogram's. Breast cancers nearly always develop in lobular
or ductal tissue (not fatty tissue). That's why cancer is more
likely to occur in breasts that have a lot of lobular and ductal
tissue (that is, dense tissue) than in breasts with a lot of
fatty tissue. In addition, when breasts are dense, it is more
difficult for doctors to see abnormal areas on a mammogram.
- Radiation therapy. Women whose
breasts were exposed to radiation during radiation therapy before
age 30, especially those who were treated with radiation for Hodgkin's
disease, are at an increased risk for developing breast cancer.
Studies show that the younger a woman was when she received her
treatment, the higher her risk for developing breast cancer later
- Alcohol. Some studies suggest
a slightly higher risk of breast cancer among women who drink
Most women who develop breast cancer have none of the risk factors
listed above, other than the risk that comes with growing older.
Scientists are conducting research into the causes of breast cancer
to learn more about risk factors and ways of preventing this disease.
Detecting Breast Cancer
Women should talk with their doctor about factors that can increase
their chance of getting breast cancer. Women of any age who are
at higher risk for developing this disease should ask their doctor
when to start and how often to be checked for breast cancer. Breast
has been shown to decrease the risk of dying from breast cancer.
Women can take an active part in the early detection of breast
cancer by having regularly scheduled screening mammogram's and
clinical breast exams (breast exams performed by health professionals).
Some women also perform breast self-exams.
A screening mammogram is the best tool available for finding breast
cancer early, before symptoms appear. A mammogram is a special
kind of x-ray. Screening mammogram's are used to look for breast
changes in women who have no signs of breast cancer.
Mammogram's can often detect a breast lump before it can be felt.
Also, a mammogram can show small deposits of calcium in the breast.
Although most calcium deposits are benign, a cluster of very tiny
specks of calcium (called
microcalcifications) may be an early sign of cancer.
If an area of the breast looks suspicious on the screening mammogram,
additional (diagnostic) mammogram's may be needed. Depending on
the results, the doctor may advise the woman to have a biopsy.
Although mammogram's are the best way to find breast abnormalities
early, they do have some limitations. A mammogram may miss some
cancers that are present (false negative) or may find things that
turn out not to be cancer (false positive). And detecting a tumor
early does not guarantee that a woman's life will be saved. Some
fast-growing breast cancers may already have spread to other parts
of the body before being detected.
Nevertheless, studies show that mammogram's reduce the risk of
dying from breast cancer. Most doctors recommend that women in
their forties and older have mammogram's regularly, every 1 to
Some women perform monthly breast self-exams to check for any changes
in their breasts. When doing a breast self-exam, it's important
to remember that each woman's breasts are different, and that
changes can occur because of aging, the menstrual cycle, pregnancy,
menopause, or taking birth control pills or other hormones. It
is normal for the breasts to feel a little lumpy and uneven. Also,
it is common for a woman's breasts to be swollen and tender right
before or during her menstrual period. Women in their forties
and older should be aware that a monthly breast self-exam is not
a substitute for regularly scheduled screening mammogram's and
clinical breast exams by a health professional.
Diagnosing Breast Cancer
To help find the cause of any sign or symptom, a doctor does
a careful physical exam and asks about personal and family medical
history. In addition, the doctor may do one or more breast exams:
- Clinical breast exam. The doctor
can tell a lot about a lump by carefully feeling it and the
tissue around it. Benign lumps often feel different from cancerous
ones. The doctor can examine the size and texture of the lump
and determine whether the lump moves easily.
X-rays of the breast can give the doctor important information
about a breast lump.
Using high-frequency sound waves, ultrasonography can often
show whether a lump is a fluid-filled cyst (not cancer) or a
solid mass (which may or may not be cancer). This exam may be
used along with mammography.
Based on these exams, the doctor may decide that no further tests
are needed and no treatment is necessary. In such cases, the doctor
may need to check the woman regularly to watch for any changes.
Often, fluid or tissue must be removed from the breast so the doctor
can make a diagnosis. A woman's doctor may refer her for further
evaluation to a surgeon or other health care professional who has
experience with breast diseases. These doctors may perform:
aspiration. A thin needle is used to remove fluid and/or
cells from a breast lump. If the fluid is clear, it may not
need to be checked by a lab.
- Needle biopsy.
Using special techniques, tissue can be removed with a needle
from an area that looks suspicious on a mammogram but cannot be
felt. Tissue removed in a needle biopsy goes to a lab to be checked
by a pathologist for cancer cells.
- Surgical biopsy.
In an incisional biopsy, the surgeon cuts out a sample of a lump
or suspicious area. In an excisional biopsy, the surgeon removes
all of a lump or suspicious area and an area of healthy tissue
around the edges. A pathologist then examines the tissue under
a microscope to check for cancer cells.
When a woman needs a biopsy, these are some questions she may want
to ask her doctor:
- What type of biopsy will I have? Why?
- How long will it take? Will I be awake? Will it hurt?
- How soon will I know the results?
- If I do have cancer, who will talk with me about treatment?
When Cancer Is Found
The most common type of breast cancer is ductal carcinoma. It
begins in the lining of the ducts. Another type, called lobular
carcinoma, arises in the lobules. When cancer is found, the pathologist
can tell what kind of cancer it is (whether it began in a duct
or a lobule) and whether it is invasive (has invaded nearby tissues
in the breast).
Special lab tests of the tissue help the doctor learn more about
the cancer. For example, hormone
receptor tests (estrogen and progesterone receptor tests) can
help determine whether hormones help the cancer to grow. If test
results show that hormones do affect the cancer's growth (a positive
test result), the cancer is likely to respond to hormonal therapy.
This therapy deprives the cancer cells of estrogen. More information
about hormonal therapy can be found in the "Planning Treatment"
Other tests are sometimes done to help the doctor predict whether
the cancer is likely to progress. For example, the doctor may order
x-rays and lab tests. Sometimes a sample of breast tissue is checked
for a gene (the human epidermal growth factor receptor-2 or HER-2
gene) that is associated with a higher risk that the breast cancer
will come back. The doctor may also order special exams of the bones,
liver, or lungs because breast cancer may spread to these areas.
If the diagnosis is breast cancer, a woman may want to ask these
- What kind of breast cancer do I have?
- What did the hormone receptor test show? What other lab tests
were done on the tumor tissue, and what did they show?
- How will you determine whether the disease has spread?
- How will this information help in deciding what type of treatment
or further tests will be best for me?
Many women with breast cancer want to take an active part in
decisions about their medical care. They want to learn all they
can about their disease and their treatment choices. However,
the shock and stress that people often feel after a diagnosis
of cancer can make it hard for them to think of everything they
want to ask the doctor. Often it is helpful to prepare a list
of questions in advance. To help remember what the doctor says,
patients may take notes or ask whether they may use a tape recorder.
Some people also want to have a family member or friend with them
when they talk to the doctor--to take part in the discussion,
to take notes, or just to listen.
The patient's doctor may refer her to doctors who specialize in
treating cancer, or she may ask for a referral. Treatment generally
begins within a few weeks after the diagnosis. There will be time
for the woman to talk with the doctor about her treatment choices,
to get a second opinion, and to prepare herself and her loved ones.
Other Sources of Information
National Alliance of Breast Cancer Organizations
Y-Me National Breast Cancer Organizations