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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. Each lobe has many smaller sections called lobules. Lobules end in dozens of tiny bulbs that can make milk. The lobes, lobules, and bulbs are linked by thin tubes called ducts.
Anatomy of the female breast. The nipple and areola are shown on the outside of the breast. The lymph nodes, lobes, lobules, ducts, and other parts of the inside of the breast are also shown.
Each breast also has blood vessels and lymph vessels. The lymph vessels carry an almost colorless, watery fluid called lymph. Lymph vessels carry lymph between lymph nodes. Lymph nodes are small, bean-shaped structures found throughout the body. They filter lymph and store white blood cells that help fight infection and disease. Groups 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.
For more information about breast cancer, see:
A family history of breast cancer and other factors increase the risk of breast cancer.
Anything that increases your chance of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn't mean that you will not get cancer. Talk to your doctor if you think you may be at risk for breast cancer.
Risk factors for breast cancer include the following:
Older age is the main risk factor for most cancers. The chance of getting cancer increases as you get older.
NCI's
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 about 5% to 10% of all breast cancer. Some mutated genes related to breast cancer are more common in certain ethnic groups.
Women who have certain gene mutations, such as a BRCA1 or BRCA2 mutation, have an increased risk of breast cancer. These women also have an increased risk of ovarian cancer, and may have an increased risk of other cancers. Men who have a mutated gene related to breast cancer also have an increased risk of breast cancer. For more information, see Male Breast Cancer Treatment.
There are tests that can detect (find) mutated genes. These genetic tests are sometimes done for members of families with a high risk of cancer. For more information, see Genetics of Breast and Gynecologic Cancers.
The use of certain medicines and other factors decrease the risk of breast cancer.
Anything that decreases your chance of getting a disease is called a protective factor.
Protective factors for breast cancer include the following:
Signs of breast cancer include a lump or change in the breast.
These and other signs may be caused by breast cancer or by other conditions. Check with your doctor if you have:
Tests that examine the breasts are used to diagnose breast cancer.
Check with your doctor if you notice any changes in your breasts. The following tests and procedures may be used:
There are four types of biopsy used to check for breast cancer:
If cancer is found, tests are done to study the cancer cells.
Decisions about the best treatment are based on the results of these tests. The tests give information about:
Tests include:
There are many types of multigene tests. The following multigene tests have been studied in clinical trials:
Based on these tests, breast cancer is described as one of the following types:
This information helps the doctor decide which treatments will work best for your cancer.
Certain factors affect prognosis (chance of recovery) and treatment options.
The prognosis and treatment options depend on:
After breast cancer has been diagnosed, tests are done to find out if cancer cells have spread within the breast or to other parts of the body.
The process used to find out whether the cancer has spread within the breast or to other parts of the body is called staging. The information gathered from the staging process determines the stage of the disease. It is important to know the stage in order to plan treatment. The results of some of the tests used to diagnose breast cancer are also used to stage the disease. (See the General Information section.)
The following tests and procedures also may be used in the staging process:
There are three ways that cancer spreads in the body.
Cancer can spread through tissue, the lymph system, and the blood:
Cancer may spread from where it began to other parts of the body.
When cancer spreads to another part of the body, it is called metastasis. Cancer cells break away from where they began (the primary tumor) and travel through the lymph system or blood.
The metastatic tumor is the same type of cancer as the primary tumor. For example, if breast cancer spreads to the bone, the cancer cells in the bone are actually breast cancer cells. The disease is metastatic breast cancer, not bone cancer.
In breast cancer, stage is based on the size and location of the primary tumor, the spread of cancer to nearby lymph nodes or other parts of the body, tumor grade, and whether certain biomarkers are present.
To plan the best treatment and understand your prognosis, it is important to know the breast cancer stage.
There are 3 types of breast cancer stage groups:
The TNM system is used to describe the size of the primary tumor and the spread of cancer to nearby lymph nodes or other parts of the body.
For breast cancer, the TNM system describes the tumor as follows:
Tumor (T). The size and location of the tumor.
Tumor sizes are often measured in millimeters (mm) or centimeters. Common items that can be used to show tumor size in mm include: a sharp pencil point (1 mm), a new crayon point (2 mm), a pencil-top eraser (5 mm), a pea (10 mm), a peanut (20 mm), and a lime (50 mm).
Lymph Node (N). The size and location of lymph nodes where cancer has spread.
When the lymph nodes are removed by surgery and studied under a microscope by a pathologist, pathologic staging is used to describe the lymph nodes. The pathologic staging of lymph nodes is described below.
or
cancer has spread to 4 to 9 axillary lymph nodes and cancer in at least one of the lymph nodes is larger than 2 millimeters. Cancer has also spread to lymph nodes near the breastbone on the same side of the body as the primary tumor, and the cancer is larger than 0.2 millimeters and is found by sentinel lymph node biopsy.
When the lymph nodes are checked using mammography or ultrasound, it is called clinical staging. The clinical staging of lymph nodes is not described here.
Metastasis (M). The spread of cancer to other parts of the body.
The grading system is used to describe how quickly a breast tumor is likely to grow and spread.
The grading system describes a tumor based on how abnormal the cancer cells and tissue look under a microscope and how quickly the cancer cells are likely to grow and spread. Low-grade cancer cells look more like normal cells and tend to grow and spread more slowly than high-grade cancer cells. To describe how abnormal the cancer cells and tissue are, the pathologist will assess the following three features:
For each feature, the pathologist assigns a score of 1 to 3; a score of "1" means the cells and tumor tissue look the most like normal cells and tissue, and a score of "3" means the cells and tissue look the most abnormal. The scores for each feature are added together to get a total score between 3 and 9.
Three grades are possible:
Biomarker testing is used to find out whether breast cancer cells have certain receptors.
Healthy breast cells, and some breast cancer cells, have receptors (biomarkers) that attach to the hormones estrogen and progesterone. These hormones are needed for healthy cells, and some breast cancer cells, to grow and divide. To check for these biomarkers, samples of tissue containing breast cancer cells are removed during a biopsy or surgery. The samples are tested in a laboratory to see whether the breast cancer cells have estrogen or progesterone receptors.
Another type of receptor (biomarker) that is found on the surface of all breast cancer cells is called HER2. HER2 receptors are needed for the breast cancer cells to grow and divide.
For breast cancer, biomarker testing includes:
Sometimes the breast cancer cells will be described as triple-negative or triple-positive.
It is important to know the estrogen receptor, progesterone receptor, and HER2 receptor status to choose the best treatment. There are drugs that can stop the receptors from attaching to the hormones estrogen and progesterone and stop the cancer from growing. Other drugs may be used to block the HER2 receptors on the surface of the breast cancer cells and stop the cancer from growing.
The TNM system, the grading system, and biomarker status are combined to find out the breast cancer stage.
Here are 3 examples that combine the TNM system, the grading system, and the biomarker status to find out the Pathological Prognostic breast cancer stage for a woman whose first treatment was surgery:
If the tumor size is 30 millimeters (T2), has not spread to nearby lymph nodes (N0), has not spread to distant parts of the body (M0), and is:
The cancer is stage IIA.
If the tumor size is 53 millimeters (T3), has spread to 4 to 9 axillary lymph nodes (N2), has not spread to other parts of the body (M0), and is:
The tumor is stage IIIA.
If the tumor size is 65 millimeters (T3), has spread to 3 axillary lymph nodes (N1a), has spread to the lungs (M1), and is:
The cancer is stage IV (metastatic breast cancer).
Talk to your doctor to find out what your breast cancer stage is and how it is used to plan the best treatment for you.
After surgery, your doctor will receive a pathology report that describes the size and location of the primary tumor, the spread of cancer to nearby lymph nodes, tumor grade, and whether certain biomarkers are present. The pathology report and other test results are used to determine your breast cancer stage.
You are likely to have many questions. Ask your doctor to explain how staging is used to decide the best options to treat your cancer and whether there are clinical trials that might be right for you.
The treatment of breast cancer depends partly on the stage of the disease.
For ductal carcinoma in situ (DCIS) treatment options, see Treatment of Ductal Carcinoma in Situ.
For treatment options for stage I, stage II, stage IIIA, and operable stage IIIC breast cancer, see Treatment of Early, Localized or Operable Breast Cancer.
For treatment options for stage IIIB, inoperable stage IIIC, and inflammatory breast cancer, see Treatment of Locally Advanced Inflammatory Breast Cancer.
For treatment options for cancer that has recurred near the area where it first formed (such as in the breast, in the skin of the breast, in the chest wall, or in nearby lymph nodes), see Treatment of Locoregional Recurrent Breast Cancer.
For treatment options for stage IV (metastatic) breast cancer or breast cancer that has recurred in distant parts of the body, see Treatment of Metastatic Breast Cancer.
In inflammatory breast cancer, cancer has spread to the skin of the breast and the breast looks red and swollen and feels warm. The redness and warmth occur because the cancer cells block the lymph vessels in the skin. The skin of the breast may also show the dimpled appearance called peau d'orange (like the skin of an orange). There may not be any lumps in the breast that can be felt. Inflammatory breast cancer may be stage IIIB, stage IIIC, or stage IV.
Inflammatory breast cancer is a type of breast cancer in which the cancer cells block the lymph vessels in the skin of the breast. This causes the breast to look red and swollen. The skin may also appear dimpled or pitted, like the skin of an orange (peau d'orange), and the nipple may be inverted (facing inward).
There are different types of treatment for patients with breast cancer.
You and your cancer care team will work together to decide your treatment plan, which may include more than one type of treatment. Many factors will be considered, such as the stage and grade of the cancer, whether certain biomarkers are present, your overall health, and your preferences. Your plan will include information about your cancer, the goals of treatment, your treatment options and the possible side effects, and the expected length of treatment.
Talking with your cancer care team before treatment begins about what to expect will be helpful. You'll want to learn what you need to do before treatment begins, how you'll feel while going through it, and what kind of help you will need. To learn more, see
The following types of treatment are used:
Surgery
Most patients with breast cancer have surgery to remove the cancer.
Sentinel lymph node biopsy is the removal of the sentinel lymph node during surgery. The sentinel lymph node is the first lymph node in a group of lymph nodes to receive lymphatic drainage from the primary tumor. It is the first lymph node the cancer is likely to spread to from the primary tumor. A radioactive substance and/or blue dye is injected near the tumor. The substance or dye flows through the lymph ducts to the lymph nodes. The first lymph node to receive the substance or dye is removed. A pathologist views the tissue under a microscope to look for cancer cells. If cancer cells are not found, it may not be necessary to remove more lymph nodes. Sometimes, a sentinel lymph node is found in more than one group of nodes. After the sentinel lymph node biopsy, the surgeon removes the tumor using breast-conserving surgery or mastectomy. If cancer cells were found, more lymph nodes will be removed through a separate incision (cut). This is called a lymph node dissection.
Types of surgery include:
Chemotherapy may be given before surgery to remove the tumor. When given before surgery, chemotherapy will shrink the tumor and reduce the amount of tissue that needs to be removed during surgery. Treatment given before surgery is called preoperative therapy or neoadjuvant therapy.
After the doctor removes all the cancer that can be seen at the time of the surgery, some patients may be given radiation therapy, chemotherapy, targeted therapy, or hormone therapy after surgery, to kill any cancer cells that are left. Treatment given after the surgery, to lower the risk that the cancer will come back, is called postoperative therapy or adjuvant therapy.
If a patient is going to have a mastectomy, breast reconstruction (surgery to rebuild a breast's shape after a mastectomy) may be considered. Breast reconstruction may be done at the time of the mastectomy or at some time after. The reconstructed breast may be made with the patient's own (nonbreast) tissue or by using implants filled with saline or silicone gel. Before the decision to get an implant is made, patients can call the Food and Drug Administration's (FDA) Center for Devices and Radiologic Health at 1-888-INFO-FDA (1-888-463-6332) or visit the
Radiation therapy
Radiation therapy is a cancer treatment that uses high-energy x-rays or other types of radiation to kill cancer cells or keep them from growing. There are two types of radiation therapy:
The way the radiation therapy is given depends on the type and stage of the cancer being treated. External radiation therapy is used to treat breast cancer. Internal radiation therapy with strontium-89 (a radionuclide) is used to relieve bone pain caused by breast cancer that has spread to the bones. Strontium-89 is injected into a vein and travels to the surface of the bones. Radiation is released and kills cancer cells in the bones.
Learn more about
Chemotherapy
Chemotherapy (also called chemo) uses drugs to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. Chemotherapy for breast cancer is usually systemic, meaning it is injected into a vein or given by mouth. When given this way, the drugs enter the bloodstream to reach cancer cells throughout the body.
To learn more about how chemotherapy works, how it is given, common side effects, and more, see
Learn more about
Hormone therapy
Hormone therapy (also called endocrine therapy) slows or stops the growth of hormone-sensitive tumors by blocking the body's ability to produce hormones or by interfering with the effects of hormones on breast cancer cells. Hormones are substances made by glands in the body and circulated in the bloodstream. Some hormones can cause certain cancers to grow. If tests show that the cancer cells have places where hormones can attach (receptors), drugs, surgery, or radiation therapy is used to reduce the production of hormones or block them from working. This is called ovarian ablation.
Types of hormone therapy for breast cancer include:
Learn more about
Targeted therapy
Targeted therapy uses drugs or other substances to identify and attack specific cancer cells. Your doctor may suggest biomarker tests to help predict your response to certain targeted therapy drugs. Learn more about
Monoclonal antibodies used to treat breast cancer include:
Learn more about
Immunotherapy
Immunotherapy helps a person's immune system fight cancer. Your doctor may suggest biomarker tests to help predict your response to certain immunotherapy drugs. Learn more about
Immune checkpoint inhibitors are a type of immunotherapy used to treat breast cancer:
This drug works in more than one way to kill cancer cells. It is also considered targeted therapy because it targets specific changes or substances in cancer cells.
immune checkpoint inhibitorsImmunotherapy uses the body's immune system to fight cancer. This animation explains one type of immunotherapy that uses immune checkpoint inhibitors to treat cancer. Learn more about
New types of treatment are being tested in clinical trials.
A treatment clinical trial is a research study meant to help improve current treatments or obtain information on new treatments for patients with cancer. For some patients, taking part in a clinical trial may be an option.
Use our
To learn more about clinical trials, see
Treatment for breast cancer may cause side effects.
To learn more about side effects that begin during treatment for cancer, visit
Some treatments for breast cancer may cause side effects that continue or appear months or years after treatment has ended. These are called late effects.
Late effects of radiation therapy are not common, but may include:
Late effects of chemotherapy depend on the drugs used, but may include:
Late effects of targeted therapy with trastuzumab, lapatinib, or pertuzumab may include:
Follow-up care may be needed.
Some of the tests that were done to diagnose or stage the cancer may be repeated to see how well the treatment is working. Decisions about whether to continue, change, or stop treatment may be based on the results of these tests. These tests are sometimes called follow-up tests or check-ups.
For information about the treatments listed below, see the Treatment Option Overview section.
Treatment of early, localized, or operable breast cancer may include:
Surgery
Postoperative radiation therapy
For women who had breast-conserving surgery, radiation therapy is given to the whole breast to lessen the chance the cancer will come back. Radiation therapy may also be given to lymph nodes in the area.
For women who had a modified radical mastectomy, radiation therapy may be given to lessen the chance the cancer will come back if any of the following are true:
Postoperative systemic therapy
Systemic therapy is the use of drugs that can enter the bloodstream and reach cancer cells throughout the body. Postoperative systemic therapy is given to lessen the chance the cancer will come back after surgery to remove the tumor.
Postoperative systemic therapy is given depending on whether:
In premenopausal women with hormone receptor positive tumors, no more treatment may be needed, or postoperative therapy may include:
In postmenopausal women with hormone receptor positive tumors, no more treatment may be needed, or postoperative therapy may include:
In women with hormone receptor negative tumors, no more treatment may be needed, or postoperative therapy may include chemotherapy.
In women with HER2 negative tumors, postoperative therapy may include chemotherapy.
In women with small, HER2 positive tumors, and no cancer in the lymph nodes, no more treatment may be needed. If there is cancer in the lymph nodes, or the tumor is large, postoperative therapy may include:
In women with small, hormone receptor negative and HER2 negative tumors (triple-negative) and no cancer in the lymph nodes, no more treatment may be needed. If there is cancer in the lymph nodes or the tumor is large, postoperative therapy may include:
Preoperative systemic therapy
Systemic therapy is the use of drugs that can enter the bloodstream and reach cancer cells throughout the body. Preoperative systemic therapy is given to shrink the tumor before surgery.
Preoperative chemotherapy may make breast-sparing surgery possible in patients who are not eligible otherwise. Preoperative chemotherapy may also lessen the need for lymph node dissection in patients with disease that has spread to the lymph nodes.
In postmenopausal women with hormone receptor positive tumors, preoperative therapy may include:
In premenopausal women with hormone receptor positive tumors, preoperative therapy may include a clinical trial of hormone therapy, such as tamoxifen or aromatase inhibitor therapy.
In women with HER2-positive tumors, preoperative therapy may include:
In women with HER2-negative tumors or triple-negative tumors, preoperative therapy may include chemotherapy.
For patients with triple-negative or HER2-positive disease, the response to preoperative therapy may be used as a guide in choosing the best treatment after surgery.
Use our
For information about the treatments listed below, see the Treatment Option Overview section.
Treatment of locally advanced or inflammatory breast cancer is a combination of therapies that may include:
Use our
For information about the treatments listed below, see the Treatment Option Overview section.
Treatment of locoregional recurrent breast cancer (cancer that has come back after treatment in the breast, in the chest wall, or in nearby lymph nodes), may include:
For information about treatment options for breast cancer that has spread to parts of the body outside the breast, chest wall, or nearby lymph nodes, see the Treatment of Metastatic Breast Cancer section.
Use our
For information about the treatments listed below, see the Treatment Option Overview section.
Treatment options for metastatic breast cancer (cancer that has spread to distant parts of the body) may include:
Hormone therapy
In postmenopausal women who have just been diagnosed with metastatic breast cancer that is hormone receptor positive or if the hormone receptor status is not known, treatment may include:
In premenopausal women who have just been diagnosed with metastatic breast cancer that is hormone receptor positive, treatment may include:
In women whose tumors are hormone receptor positive or hormone receptor unknown, with spread to the bone or soft tissue only, and who have been treated with tamoxifen, treatment may include:
Targeted therapy
In women with metastatic breast cancer that is hormone receptor positive and has not responded to other treatments, options may include targeted therapy such as:
In women with metastatic breast cancer that is HER2 positive, treatment may include:
In women with metastatic breast cancer that is HER2 negative, with mutations in the BRCA1 or BRCA2genes, and who have been treated with chemotherapy, treatment may include targeted therapy with a PARP inhibitor (olaparib or talazoparib).
Chemotherapy
In women with metastatic breast cancer that has not responded to hormone therapy, has spread to other organs, or has caused symptoms, treatment may include chemotherapy with one or more drugs.
Chemotherapy and immunotherapy
In women with locally recurrent, inoperable, or metastatic triple-negative breast tumors which express PD-L1, treatment may include chemotherapy and immunotherapy (pembrolizumab).
Surgery
Radiation therapy
Other treatment options
Other treatment options for metastatic breast cancer include:
Use our
For information about the treatments listed below, see the Treatment Option Overview section.
Treatment of ductal carcinoma in situ may include:
Use our
For more information from the National Cancer Institute about breast cancer, see:
For general cancer information and other resources from the National Cancer Institute, visit:
About PDQ
Physician Data Query (PDQ) is the National Cancer Institute's (NCI's) comprehensive cancer information database. The PDQ database contains summaries of the latest published information on cancer prevention, detection, genetics, treatment, supportive care, and complementary and alternative medicine. Most summaries come in two versions. The health professional versions have detailed information written in technical language. The patient versions are written in easy-to-understand, nontechnical language. Both versions have cancer information that is accurate and up to date and most versions are also available in
PDQ is a service of the NCI. The NCI is part of the National Institutes of Health (NIH). NIH is the federal government's center of biomedical research. The PDQ summaries are based on an independent review of the medical literature. They are not policy statements of the NCI or the NIH.
Purpose of This Summary
This PDQ cancer information summary has current information about the treatment of adult breast cancer. It is meant to inform and help patients, families, and caregivers. It does not give formal guidelines or recommendations for making decisions about health care.
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Editorial Boards write the PDQ cancer information summaries and keep them up to date. These Boards are made up of experts in cancer treatment and other specialties related to cancer. The summaries are reviewed regularly and changes are made when there is new information. The date on each summary ("Updated") is the date of the most recent change.
The information in this patient summary was taken from the health professional version, which is reviewed regularly and updated as needed, by the
Clinical Trial Information
A clinical trial is a study to answer a scientific question, such as whether one treatment is better than another. Trials are based on past studies and what has been learned in the laboratory. Each trial answers certain scientific questions in order to find new and better ways to help cancer patients. During treatment clinical trials, information is collected about the effects of a new treatment and how well it works. If a clinical trial shows that a new treatment is better than one currently being used, the new treatment may become "standard." Patients may want to think about taking part in a clinical trial. Some clinical trials are open only to patients who have not started treatment.
Clinical trials can be found online at
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PDQ® Adult Treatment Editorial Board. PDQ Breast Cancer Treatment. Bethesda, MD: National Cancer Institute. Updated <MM/DD/YYYY>. Available at:
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Last Revised: 2024-08-23
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