Breast cancer is cancer cells that start in the breast. The breast is made up of lobules and ducts. The lobules are surrounded by fat blood vessels, and lymph and connective tissue. Breast cancer can start and grow in all these areas. Some types of breast cancer are:
- Ductal carcinoma in situ—found in the ducts
- Invasive ductal carcinoma—starts in the ducts and spreads to surrounding tissues
- Invasive lobular carcinoma—starts in the lobules and spreads to surrounding tissues
- Inflammatory— invades the lymph vessels and often spreads to other parts of the body
- Paget disease of the breast—found in the areola and nipple
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Cancer happens when cells divide without control or order. These cells grow together to form a tumor. They can then invade and damage nearby tissues. Cancer can also spread to other parts of the body.
It is not clear what causes changes in the cells. It is likely a combination of genes and environment.
Breast cancer is most common in women over 40. Other things that may raise the risk are:
- Family and genetic risks, such as:
Family members with breast cancer
- Certain genes, such as BRCA1 and BRCA2
- Rare genetic conditions such as Li-Fraumeni syndrome
Increased exposure to estrogen, due to:
- Early menstruation
- Late menopause
- No childbearing or late childbearing
- Hormone replacement therapy
Excess body weight or obesity—especially after
- Smoking, or drinking too much alcohol
- A history of breast atypical hyperplasia or lobular carcinoma in situ
- Dense breasts
- Previous breast cancer
- Radiation exposure
Some breast cancers have no symptoms. Others may eventually cause:
- One or more lumps in the breast
- One or more lumps near the breast—or under the arm or collarbone
- A change in the way the breast or nipple looks or feels, such as:
- Thickening in or around the breast
- A change in the size or shape of the breast
- Inward sinking of the nipple
- Ridges or pitting of the breast skin,
- Breast skin that is red, sore, or flaky
- Nipple discharge or soreness
- Breast pain
Breast cancer may be found during a mammogram screening.
Breast changes may also be found during a regular health visit. The doctor will ask about your symptoms and past health. A physical exam, breast exam, and blood tests will be done.
Images may show abnormal growth or changes in the breasts. Tests may include:
A biopsy of abnormal area will be done. A sample of tissue and nearby lymph nodes will be taken and tested for cancer cells. This can be done with:
- Fine needle aspiration
—uses a thin needle to remove fluid and/or cells from a breast lump
- Core needle—uses a larger, hollow needle to remove a wider area of tissue
—a or part of a breast lump is removed
Diagnosis is confirmed by the tests. Blood and other tissue tests may be done to look for more information about the type of cancer. The tests can show what type of receptors the cancer has. This is called the biomarker. The cancer is also given a grade to show how likely it is to grow and spread.
The test results, biomarkers, and grade will be used to determine the stage. The stage will help determine the treatment plan.
The goal is to remove the cancer and stop it from coming back or spreading. Treatment is based on the person's health and the stage and type of cancer. One or more treatments may be used.
Options may be:
- Surgery to remove as much cancer as possible, such as:
- Lumpectomy—removal of the breast cancer, some area tissue, and sometimes lymph nodes
Mastectomy—removal of the breast, and sometimes lymph nodes and other tissues
- External or internal radiation therapy—may be used before surgery to help shrink tumors or after to make sure all cancer was removed. May also be used to treat large tumors that are causing problems.
- Chemotherapy drugs by mouth, injection, or IV—to kill cancer cells.
- Medicines, such as:
- Targeted therapy—special antibodies are made to help attack cancer cells. May keep cancer cells from growing and spreading or kill cancer cells.
- Hormone-blocking therapy—to slow or stop growth in certain types of breast cancer. Medication is taken over several years to help prevent recurrence.
- Biological therapy—trains or boosts the immune system to fight cancer.
Avoiding risk factors may help to decrease risk of cancer. The risk of breast cancer may be lowered by:
Reaching and keeping a healthy weight
- Regular physical activity
- Avoiding or limiting alcohol
Women with a very high risk may benefit from hormone therapies or other treatments.
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General information about breast cancer. National Cancer Institute website. Available at: https://www.cancer.gov/types/breast/patient/breast-treatment-pdq. Accessed March 25, 2021.
How radiation works. Breast Cancer website. Available at: http://www.breastcancer.org/treatment/radiation/how_works. Accessed March 25, 2021.
Planning your treatment. Breast Cancer website. Available at: http://www.breastcancer.org/treatment/planning. Accessed March 25, 2021.
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Last reviewed January 2021 by
EBSCO Medical Review Board
Mohei Abouzied, MD, FACP
Last Updated: 3/25/2021