Treatment for Breast Cancer

How do doctors decide on a treatment plan?

Doctors base their treatment recommendations on several factors, including:

• the stage of your cancer
• the subtype based on pathology
• genetic test results 
• biomarker test results
• how fast the cancer is growing or how likely it is to spread
• whether the cancer is newly-diagnosed or has recurred after one or more treatments
• your overall health

Make sure that you receive a copy of your records. Ask your doctor to explain your diagnosis, test results, pathology report, stage, prognosis and treatment recommendations in terms that you can understand. This will allow you to work with your doctor to choose a treatment plan that is right for you. 

Most breast cancer is treated with one or more of the following treatments. Every treatment has potential risks and side effects. Before any new treatment or surgery, make sure your healthcare team tells you about what to expect.

Surgery

Most breast cancers are treated with one of the following types of surgery. 

• Lumpectomy (surgery to remove the cancer but not the entire breast). Lumpectomy is often followed by radiation.
• Mastectomy (removal of the entire breast). 
• Lymph nodes are removed to see whether, and how much the cancer has spread.

Radiation therapy

Radiation therapy is used to treat breast cancer in the following ways: 

• In early breast cancer to treat the breast and surrounding tissue after surgery to prevent recurrence.
• In people with metastatic breast cancer which has spread to their bones, brain or other sites to reduce the size of the tumor and manage pain or other symptoms.

Hormone therapy

Most people with HR-positive cancers receive hormone therapy after surgery. The most common types of hormone therapies are: 

• SERMs (selective estrogen receptor modulators) block cells from using estrogen. Example of common SERMs include tamoxifen and raloxifene.
• SERDs (selective estrogen receptor degraders) damage the receptors that allow cancer cells to feed on estrogen. The SERDs with FDA approval include Faslodex (fulvestrant), Inluriy (imlunestrant), Oserdu (elacestrant) and a targeted SERD known as Veppanu (vepdegestrant). 
• Aromatase inhibitors block cells from making estrogen. Examples of aromatase inhibitors include Arimidex (anastrozole), Femara (letrozole) and Aromasin (exemestane).  

Chemotherapy

Chemotherapy may be used to treat breast cancer in the following ways: 

• For early stage breast cancer, chemotherapy may be given before surgery to shrink the size of the cancer and number of lymph nodes affected. This is known as neoadjuvant therapy. 
• For early stage breast cancer, chemotherapy may be given after surgery to kill any remaining cancer cells that may have escaped the breast area. This is known as adjuvant therapy. 
• For people with metastatic breast cancer, chemotherapy may be given to keep the cancer from growing.

How is targeted therapy used in breast cancer?

Targeted therapy is a type of cancer treatment designed to attack or kill cancer cells, while sparing normal cells as much as possible. The targeted therapies used in breast cancer are designed to target abnormal proteins, receptors or genes that are found in breast cancer cells or the surrounding tissue. See below for more information on the different targeted therapies used to treat breast cancer. 

Also see our general section on targeted therapy for more information about the different types of targeted therapy drugs, their uses and side effects. 

How is immunotherapy used in breast cancer?

Immunotherapies are cancer treatments that help the body’s immune system detect and attack cancer cells.

Immune checkpoint inhibitors are a type of immunotherapy used to treat several types of cancer, including breast cancer. Some cancer cells can switch off the immune system. Immune checkpoint inhibitors prevent this from happening. This allows the immune system to find, unmask and destroy cancer cells. Other names for these drugs are:

• PD-1/PD-L1 inhibitors
• PD-1/PD-L1-directed therapies

See the tables below for a list of immunotherapies used to treat breast cancer.

See our general section on immunotherapy for more information on different types of immunotherapy, how they work and their possible side effects. 

PARP inhibitors for BRCA-positive breast cancer

PARP inhibitors are a type of targeted therapy that works by blocking a protein that the body uses to repair DNA damage. They were initially developed to treat cancers in people with an inherited BRCA1 or BRCA2 mutation. In breast cancer, PARP inhibitors are only FDA approved for treatment in people with a BRCA1 or BRCA2 inherited mutation. However, some expert guidelines support use of PARP inhibitors off label for treating people with PALB2 mutations.  

PARP inhibitors for early stage breast cancer at high risk for recurrence

Lynparza may be used as adjuvant treatment after chemotherapy in people with an inherited BRCA1 or BRCA2 mutation. 

PARP inhibitors for metastatic breast cancer

Two PARP inhibitors have FDA-approval for treating metastatic breast cancer in people with a BRCA mutation:

• Lynparza (olaparib) 
• Talzenna (talazoparib)

If you have a PALB2 mutation and breast cancer and your health plan has denied coverage for a PARP inhibitor, download our sample appeal letter. 

PARP inhibitors in research

Researchers are studying new ways to use PARP inhibitors to treat breast cancer, including:  

• for people with an inherited mutation in a different gene that repairs DNA damage (e.g., PALB2, ATM, RAD51C or RAD51D).
• for people who do not have an inherited gene mutation, but biomarker testing found an acquired mutation in a gene that repairs DNA damage.

Visit our Featured Research section for more information.

Targeted therapy and immunotherapy for triple-negative breast cancers (TNBC)

With the exception of PARP inhibitors (described above) which may be used to treat early-stage cancers with BRCA mutations, most breast cancer targeted therapies used for TNBC are approved in the advanced or metastatic setting. Immunotherapies are FDA approved for both early-stage and metastatic TNBC.

Targeted therapy for advanced or metastatic TNBC

• Trodelvy (sacituzumab govitecan) is FDA approved to treat metastatic TNBC that has progressed, recurred or did not respond to at least two previous lines of treatment. 
• Datroway (datopotamab deruxtecan-dlnk or Dato-DXd) is FDA approved to treat advanced or metastatic TNBC when treatment with an immunotherapy (PD-1 or PD-L1 inhibitor) is not an option. 

Immunotherapy for early-stage TNBC

• Keytruda is approved for the treatment of early-stage TNBC that is at high risk for recurrence. In this setting, Keytruda is used along with chemotherapy as neoadjuvant therapy before surgery. Following surgery, Keytruda is continued alone.

Immunotherapy for advanced or metastatic TNBC

• Keytruda (pembrolizumab) is approved in combination with chemotherapy for treatment of triple-negative breast cancer that is metastatic or locally recurrent and unresectable that tests positive for a biomarker called PD-L1.
• The immunotherapy drugs Keytruda and Jemperli (dostarlimab) are also approved for treating multiple types of cancer if they are metastatic, have few remaining treatment options, and have any of the following biomarkers (which are found very rarely in breast cancer):
  • dMMR or MMR-d (Jemperli)
  • MSI-high (Keytruda)
  • TMB-high (Keytruda)

Targeted therapy for hormone receptor-positive (HR-positive), HER2-negative breast cancers

Targeted therapies are used for both early-stage and metastatic for HR-positive breast cancers. 

Targeted therapies for early-stage HR-positive breast cancer 

CDK4/6 inhibitors

CDK4/6 inhibitors are oral medications that target proteins found in some breast cancers called CDK proteins. Although they are considered targeted therapies, they do not require additional biomarker testing beyond the standard hormone receptor tests (estrogen receptor and progesterone receptor testing). 

• Two CDK4/6 inhibitors are approved for use in early-stage breast cancer: 
  • Kisqali (ribociclib)
  • Verzenio (abemaciclib)

Targeted therapies for advanced or metastatic HR-positive breast cancer

• Three CDK4/6 inhibitors are approved for use in advanced, HR-positive breast cancer: 
  • Ibrance (palbociclib)
  • Kisqali (ribociclib)
  • Verzenio (abemaciclib)
• Datroway (datopotamab deruxtecan-dlnk or Dato-DXd) is FDA approved to treat metastatic, HR-positive breast cancer which recurred or got worse after hormone therapy and chemotherapy. 
• Afinitor (everolimus) is a targeted therapy which may be used in combination with Aromasin (exemestane) for postmenopausal women with advanced breast cancer which progressed with Femara (letrozole) or Arimidex (anastrozole)

Therapies for advanced or metastatic, HR-positive breast cancer that require additional biomarker testing

• HR-positive breast cancers that progressed on or after treatment with hormone therapy may be treated with the drug Piqray (alpelisib).combined with Faslodex (fulvestrant). The drag is approved to treat HR-positive breast cancer with a biomarker called PIK3CA.   
• HR-positive, advanced or metastatic breast cancer which recurred or got worse after standard hormone therapy may be treated with the drug Truqap (capivasertib) combined with fulvestrant. This treatment is for cancers that have certain changes in PIK3CA, AKT1 or PTEN, found through biomarker testing.
• SERDs (selective estrogen receptor degraders) are a type of hormone therapy that works by damaging the receptors that allow cancer cells to feed on estrogen. The three SERDs listed below are FDA approved to treat breast cancers that progressed or recurred after at least one line of hormone therapy. These drugs are for cancers that have a biomarker known as an ESR1 mutation. 
  •  Inluriy (imlunestrant)
  • Oserdu (elacestrant)
  • Veppanu (vepdegestrant).

Targeted therapy for HER2-positive or HER2-low breast cancers

Medications that treat HER2-positive, HER2-low and HER2-ultralow cancers are called "anti-HER2 therapies." These drugs may be used to treat both early-stage and metastatic breast cancer. Commonly-used anti-HER2 therapies used to treat HER2-positive breast cancers include:

• Herceptin (trastuzumab)
• Perjeta (pertuzumab)
• Tukysa (tucatinib) 
• Phesgo (pertuzumab, trastuzumab and hyaluronidase)
• Enhertu (T-DXd).

Metastatic or advanced HER2-low or HER2-ultralow breast cancers may also be treated with the anti-HER2 drug Enhertu. 

Treatment side effects

Your healthcare team should explain what you should expect from all treatments, including:

• all of the possible risks and side effects of each treatment.
• which side effects may be serious and how to tell. 
• when and who you should call if you experience a side effect.
• what can be done to treat or alleviate each side effect. 

Make sure you let your healthcare team know if you experience any side effects of your treatment. For more information about possible treatment side effects, see our section on Cancer Treatment by Treatment Type.