General Information About Breast Cancer
Key Points for This Section
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Breast cancer is a disease in which malignant (cancer) cells
form in the tissues of the breast.
The breast is made up of lobes and ducts. Each breast has 15 to 20 sections called
lobes, which have many smaller sections called lobules. Lobules end in dozens of tiny bulbs that
can produce milk. The lobes, lobules, and bulbs are linked by thin tubes called
ducts.
Each breast also has blood
vessels and lymph
vessels. The lymph vessels carry an almost colorless fluid called lymph. Lymph
vessels lead to organs called lymph
nodes. Lymph nodes are small bean-shaped structures that are
found throughout the body. They filter substances in lymph and help fight
infection and disease. Clusters of lymph nodes are found near the breast in the
axilla (under the arm), above the
collarbone, and in the chest.
The most common type of breast cancer is ductal
carcinoma, which begins in the cells of the ducts. Cancer that begins in the
lobes or lobules is called lobular carcinoma and is more often found in both
breasts than are other types of breast cancer. Inflammatory breast cancer is an uncommon type of
breast cancer in which the breast is warm, red, and swollen.
Age and health history can affect the risk of developing breast
cancer.
Anything that increases your chance of getting a disease
is called a risk factor. Risk factors for breast cancer include the following:
- Older age.
- Menstruating at an
early age.
- Older age at first birth or never having given birth.
- A personal history of breast cancer or benign (noncancer) breast disease.
- A mother or sister with breast cancer.
- Treatment with radiation therapy to the breast/chest.
- Breast tissue that is dense on a mammogram.
- Hormone use (such as estrogen and progesterone).
- Drinking alcoholic beverages.
- Being white.
Breast cancer is sometimes caused by inherited gene mutations
(changes).
The genes in cells carry
the hereditary information that is
received from a person’s parents. Hereditary breast cancer makes up
approximately 5% to 10% of all breast cancer. Some altered genes related to
breast cancer are more common in certain ethnic groups.
Women who have an altered gene related to breast cancer and who
have had breast cancer in one breast have an increased risk of developing
breast cancer in the other breast. These women also have an increased risk of
developing ovarian cancer, and may
have an increased risk of developing other cancers. Men who have an altered
gene related to breast cancer also have an increased risk of developing this
disease. (For more information, refer to the PDQ summary on
Male Breast Cancer Treatment.)
Tests have been developed that can detect altered genes. These
genetic tests are sometimes done for
members of families with a high risk of cancer. (Refer to the PDQ summaries on
Screening for Breast
Cancer, Prevention of
Breast Cancer, and Genetics of Breast and Ovarian Cancer for
more information.)
Tests that examine the breasts are used to detect (find) and
diagnose breast cancer.
A doctor should be seen if changes in the breast are noticed. The
following tests and procedures may be used:
- Mammogram: An
x-ray of the breast.
- Biopsy: The removal
of cells or tissues so they can be viewed under a microscope to check for signs of cancer. If a lump in the breast is
found, the doctor may need to cut out a small piece of the lump. A pathologist views the tissue under a microscope to look for cancer cells. Four types of
biopsies are as follows:
- Estrogen and
progesterone receptor test: A test to measure the amount of estrogen and progesterone (hormones) receptors in cancer tissue. If cancer is found in the breast, tissue from the tumor is examined in the laboratory to find out whether estrogen and progesterone could affect the way cancer grows. The test results show whether hormone therapy may stop the cancer from growing.
Certain factors affect prognosis (chance of recovery) and treatment options.
The prognosis (chance of recovery) and treatment options depend on the following:
- The stage
of the cancer (whether it is in the breast only or has spread to lymph nodes or other places
in the body).
- The type of breast cancer.
- Estrogen-receptor and progesterone-receptor levels in the tumor tissue.
- A woman’s age,
general health, and menopausal status (whether a woman
is still having menstrual periods).
- Whether the cancer has just been diagnosed or has recurred (come back).
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