Breast Cancer Treatment and Staging

Breast Cancer Stages

Staging of a cancer refers to the determination of how much of the cancer there is and how far the cancer has spread at the time of diagnosis. Staging helps determine both a woman's prognosis and guides her treatment plan options. Staging is determined by a variety of methods, including results from surgical procedures, lymph node biopsy, and imaging tests.

Cancer in situ (DCIS or LCIS) is referred to as stage 0, because the tumor cells have not even begun to spread outside the ducts or lobules into the adjacent breast tissue. Invasive breast cancers are staged I through IV, with stage I being the earliest stage and easiest to treat, while stages II and III represent advancing cancer, with stage IV representing breast cancer cells that have spread (metastasized) to distant organs like the bones, lungs, or brain. Upon spreading these metastases become detectable when they have divided enough times to form detectable masses or metastatic tumors.

Breast Cancer Treatment

Treatment for breast cancer is individualized and is based upon many factors. A woman's health-care team will help her make the choice that is best for her. In general, treatment decisions typically depend upon many factors, including the following:

  • The type of cancer that is present
  • The stage of the tumor (the extent of spread at the time of diagnosis)
  • Whether or not the tumor expresses ER, PR, and/or HER2
  • A woman's age, both biological and chronological, (whether or not she has gon through menopause) and overall health
  • A woman's preferences, which must be paramount in the decision process
  • The results of specialized testing performed on the tumor, such as gene expression analysis

Treatment may include a combination of surgery, radiation therapy, hormone therapy, chemotherapy, and targeted therapy. A woman may also elect to participate in a clinical trial or newer treatments.

Breast Cancer Surgery

Surgery is the most common type of treatment for breast cancer. Different surgical treatments are available for early stage breast cancers. Mastectomy is the removal of the entire breast. Breast-conserving surgery, such as lumpectomy or partial mastectomy, can also be appropriate for some women. If a breast conserving surgery is combined with post operative radiation therapy, it is as effective at curing breast cancer as a mastectomy. Sentinel lymph node biopsy (removing the first lymph node that drains the affected area) should be performed in invasive breast cancer cases staged I to III to assess whether the cancer has begun to spread to nearby lymph nodes. If the lymph nodes contain cancer, an axillary dissection may sometimes be done to remove and examine other nearby lymph nodes.

Reconstructive surgery may be done either at the time of mastectomy or at a later time to recreate the shape of the breast.

Radiation for Breast Cancer

Radiation therapy is a common treatment for women who have had breast-conserving surgery. It is also sometimes given to women who have had a mastectomy, particularly if there has been spread of the tumor to the chest wall muscles or skin, or to the reginal lymph nodes. This treatment uses high-energy rays to destroy remaining cancer cells. Radiation therapy can be given externally or internally. External radiation therapy is given in a clinic, usually five days a week for several weeks. This is the most common kind of radiation therapy used to treat breast cancer. However, in some cases, internal radiation therapy can be used. This involves the placement of radioactive material directly into the breast tissue through thin tubes. After a short time period, the material is removed. This can be repeated on a daily basis for a week. Administering radioactive material inside the body is known as brachytherapy.


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Hormone Therapy for Breast Cancer

Hormone therapy is an effective form of treatment for cancers that are positive for hormone receptors (ER and PR). Hormone therapy is designed to deprive the tumor cells of the hormones they need to grow and can be given as different types of drugs. Tamoxifen, a drug that interferes with the activity of estrogen in the body, is a common hormone therapy drug. It can be given to both premenopausal and postmenopausal women. Studies have shown that taking tamoxifen for five years after surgical removal of the tumor improves outcomes in women with ER-positive breast cancer. In postmenopausal women, the drug class known as aromatase inhibitors is also used as a form of hormone therapy. Examples of aromatase inhibitors approved by the FDA are anastrozole (Arimidex), letrozole (Femara), and exemestane (Aromasin).

Chemotherapy for Breast Cancer

Chemotherapy involves the use of drugs to kill rapidly dividing cancer cells. Chemotherapy is added to the treatment regimen for some women. Chemotherapy may be given after surgery (known as adjuvant chemotherapy) or before surgery in certain cases (neoadjuvant chemotherapy). Most chemotherapy regimens involve combinations of drugs.

Targeted Therapy for Breast Cancer

Targeted therapy involves drugs designed to target the HER2 protein on the surface of breast cancer cells in tumors that overexpress this protein. These therapies are given to women who have tumors that have been classified as HER2-positive. Trastuzumab (Herceptin) is a monoclonal antibody that blocks the tumor growth-promoting activity of HER2. Other drugs that target HER2 activity have also been developed.

Breast Cancer Treatment by Stage

Stage 0: DCIS, or ductal carcinoma in situ, is breast cancer that has not become invasive. Recently, there has been a great deal of interest in the diagnosis of this condition and the potential for overdiagnosis and overtreatment because as few as 14% to as many as 50% of cases of DCIS will ever turn into invasive cancer. Currently, surgical removal is used to treat DCIS, and radiation therapy is often given to reduce the risk of recurrence of the condition.

Stage 1 and 2 breast cancers are treated by removal of the cancer, either by a lumpectomy or mastectomy. Stage 1 cancers are small and either have not spread to the lymph nodes or have only spread to a tiny area within the lymph nodes. Stage 2 cancers are somewhat larger or have spread to a few lymph nodes. Lymph node removal, either a biopsy of a nearby lymph node (sentinel node biopsy) or removal of more lymph nodes, is typically done at surgery. Radiation therapy is typically given after breast conserving surgery (lumpectomy) or even after mastectomy in some cases. Following the surgery, if the tumor expresses hormone receptors, hormone therapy with tamoxifen or aromatase inhibitors (as described above) may be given. Drugs that target HER2 activity are given to those whose tumors overexpress this protein. Chemotherapy may also be given. Sometimes, neoadjuvant chemotherapy is given prior to surgery in order to shrink the tumor so that a less extensive surgical operation can be performed.

Stage 3 breast cancers are larger tumors that have spread to many lymph nodes or have spread to structures like the chest wall adjacent to the breast. These tumors have not spread to distant sites within the body. Stage 3 tumors are also treated with surgery, which may be followed by radiation therapy. Hormone therapy, chemotherapy, and drugs to target HER2 activity are often used, depending on the specific characteristics of the tumor. Chemotherapy may also be given prior to surgery (called neoadjuvant chemotherapy) for stage 3 tumors.

Stage 4 (metastatic) breast cancers have spread to other sites in the body. Because stage 4 tumors are widespread, systemic (body-wide) rather than local treatments are usually chosen. In most cases, a combination of chemotherapy, hormone therapy, and/or biologic therapy is the main treatment. Chemotherapy and radiation therapy may be done in some cases.

Clinical trials are often available to test new medications, combinations of drugs, and hormone therapies. Trials may also be designed to determine the proper length of therapy or drug dosing. Many people with breast cancer receive treatment through a clinical trial.

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Breast cancer awareness

Breast Cancer Facts and Awareness

Breast cancer is cancer arising in breast tissue. Cancers are diseases that start as abnormalities developed in cells, leading to abnormal growth patterns. Cancers can grow in place in their tissue of origin or spread (metastasize) to other parts of the body.

  • Although breast cancer is primarily a disease of women, about 1% of breast cancers occur in men.
  • Breast cancer is the most common type of cancer in women with the exception of nonmelanoma skin cancers. It is the second leading cause of death by cancer in women, following only lung cancer.
  • A woman has a lifetime risk of developing invasive breast cancer of about one in eight, or about 12% over the course of their entire lifetime. That risk is lower when they are younger and increases with age.
  • Death rates from breast cancer have been gradually declining and continue to decline. These decreases are likely due both to increased breast cancer awareness and screening and improved treatment methods.
  • There are currently about 2.8 million breast cancer survivors in the U.S.
  • In 2016, the American Cancer Society estimated that 246,660 new cases of invasive breast cancer would be diagnosed among women in the United States and that a further 61,000 new cases of in-situ (noninvasive) breast cancer would be diagnosed.
Medically reviewed by Jay B. Zatzkin, MD; American Board of Internal Medicine with subspecialty in Medical Oncology


American Cancer Society. "Breast Cancer Overview." <>.

Stopeck, Alison T. "Breast Cancer." Sept. 16, 2014. <>.

United States. National Cancer Institute. "Breast Cancer." Sept. 26, 2012. <>.

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