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General Information About Breast Cancer
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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. | Enlarge | | | | Anatomy of the breast, showing lymph nodes and lymph vessels. |
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 a fluid called 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.
See the PDQ summary on Unusual Cancers of Childhood for information about childhood breast cancer.
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.
- Taking hormones such as estrogen and progesterone.
- Drinking alcoholic beverages.
- Being white.
NCI's Breast Cancer Risk Assessment Tool uses a woman's risk factors to estimate her risk for breast cancer during the next five years and up to age 90. This online tool is meant to be used by a health care provider. For more information on breast cancer risk, see Estimating Breast Cancer Risk: Questions and Answers or call 1-800-4-CANCER.
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, see 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. See the following PDQ summaries 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.
| Enlarge | | | | Mammography of the right breast. |
- Biopsy: The removal
of cells or tissues so they can be viewed under a microscope by a pathologist to check for signs of cancer. If a lump in the breast is
found, the doctor may need to remove a small piece of the lump. 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 checked 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.
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MRI (magnetic resonance imaging): A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of areas inside the body. This procedure is also called nuclear magnetic resonance imaging (NMRI).
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 (the size of the tumor and 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.
- Whether the cells have high levels of human epidermal growth factor type 2 receptors (HER2/neu).
- How fast the tumor is growing.
- 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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