• HER2-positive breast cancer is often treated with targeted therapies that can specifically find and kill cells that have the HER2 protein.
• Other possible treatments for HER2-positive breast cancer include surgery, radiation, chemotherapy, and hormone therapy.
• Stick to your treatment plan as directed, for as long as directed, to get the best outcome and avoid negative effects.

Many treatments are now available that have been designed to specifically target HER2-positive breast cancer cells. These treatments have led to better outcomes for many individuals with this breast cancer subtype.

About 20 percent of people with breast cancer have HER2-positive tumors.

Read more details about the HER2 gene and breast cancer prognosis.

Stages of Breast Cancer Treatment

Breast cancer treatments are often given in stages. These stages are described using specific terms:

• First-line therapy, also called induction therapy, refers to the first set of treatments that you receive.
• Neoadjuvant therapy is a first-line therapy used to make a tumor smaller before it is surgically removed.
• Adjuvant therapy is prescribed to help keep your cancer from returning once first-line treatments have effectively eliminated the tumor.
• Second-line therapy refers to treatments you may receive if the first-line treatments don’t work or cause too many side effects.

At various points during breast cancer treatment, your doctor may have you repeat HER2 testing. Results can help show whether the cancer is responding to treatment.

Read more about HER2 tests and diagnosis.

HER2-Positive Breast Cancer Treatments

If you have early-stage breast cancer (cancer that has not yet spread throughout the body), the goal of treatment will most likely be to eliminate the entire breast tumor. If your cancer is metastatic (has spread to other areas), you may also receive treatments to get rid of these metastases. In cases of advanced breast cancer, however, the treatment goal may be different. You may receive treatments that aim to make the tumor grow more slowly or lessen your cancer symptoms.

The breast cancer treatment plan that is best for you may be very different from the treatment plan for someone else. Several considerations go into deciding which cancer treatment plan is a good fit for your needs, including:

• Your age
• Other health conditions you may have
• The type of breast cancer you have
• The stage and grade of your tumor
• Whether you are still having your period (premenopausal) or have gone through menopause (postmenopausal)
• Genetic changes found in your tumor, including whether it is HER2-positive or HER2-negative
• Your personal preferences

Targeted Therapy

People with HER2-positive breast cancer often begin treatment by receiving targeted therapy. Medications in this category are often given as both neoadjuvant and adjuvant treatments. Targeted therapies are able to specifically recognize and kill HER2-positive breast cancer cells.

Monoclonal Antibodies

The immune system makes proteins called antibodies to fight harmful things like viruses and cancer. Each antibody is able to recognize and attach to a specific substance, such as a particular protein or cell, and signal to the rest of the immune system to attack that target.

Antibodies can be manufactured in a laboratory and designed to attack targets on cancer cells. When antibodies are manufactured, they are called monoclonal antibodies. Researchers have designed several anti-HER2 monoclonal antibodies that can recognize and attack the HER2 protein.

Herceptin (trastuzumab) was the first monoclonal antibody approved by the U.S. Food and Drug Administration (FDA) to treat HER2-positive breast cancer. In the following years, the antibody Perjeta (pertuzumab) was also approved. The more recently approved Ogivri (trastuzumab-dkst), a biosimilar of Herceptin, is also available.

These medications:

• Attach to HER2 and prevent it from sending growth signals to the cell
• Can be taken before and after surgery
• May be taken for up to a year
• May be taken alone or prescribed with chemotherapy

You can also take Herceptin and Perjeta together. This combination may make it more likely that all traces of cancer are removed from your body. Additionally, breast cancer cells may sometimes become resistant to one monoclonal antibody, so it can be helpful to use a combination.

IV vs. Injection

Monoclonal antibodies are often given intravenously (through an IV). With an IV, a tube is inserted into your vein, and medication is delivered directly into your veins. Each dose of a monoclonal antibody may take between 30 minutes and 90 minutes. IV infusions involve going to a hospital or clinic.

More recently, researchers have developed other forms of monoclonal antibodies that can be given subcutaneously (through an injection into the tissue underneath the skin). This only takes a few minutes, and you may be able to have it done at your doctor’s office. This medication is called Phesgo (trastuzumab, pertuzumab, and hyaluronidase). Because injections don’t take as long, studies have found that 85 percent of people receiving Phesgo prefer this medication over IV drugs.

Kinase Inhibitors

HER2 belongs to a family of proteins called kinases. Kinase inhibitors are medications that can stop kinase proteins from doing their jobs. Drugs in this category that may be used to treat HER2-positive breast cancer include Nerlynx (neratinib), Tukysa (tucatinib), and Tykerb (lapatinib).

Kinase inhibitors are most often used to treat later-stage cancer or as a second-line treatment for earlier-stage tumors. These drugs usually come in the form of a pill that you take by mouth.

Antibody-Drug Conjugates

An antibody-drug conjugate (ADC) is a combination of targeted therapy and chemotherapy. ADCs contain a monoclonal antibody that helps the drug find cells that have the HER2 protein. The chemotherapy part of the drug then kills the cancer cell. ADC medications that may be given to people with HER2-positive breast cancer include TDM-1 or Kadcyla (ado-trastuzumab emtansine) and Enhertu (fam-trastuzumab deruxtecan-nxki).

You may be prescribed an ADC as a second-line treatment for early-stage breast cancer or as a therapy for metastatic breast cancer. ADCs are usually delivered through an IV.

Surgery

There are several types of surgery you may receive over the course of breast cancer treatment. During a lumpectomy, the tumor and a small part of the surrounding breast are removed. In a mastectomy, the entire breast is removed. Some data shows individuals with HER2-positive breast cancer may be more likely to have a mastectomy. Either of these surgeries may later be followed by reconstructive surgery to help repair the breast.

People with breast cancer may also receive surgery to remove the lymph nodes — small structures that help filter harmful substances out of the body. By looking more closely at the lymph nodes, your doctor can determine whether cancer cells have begun to spread beyond the breast.

Surgery aims to remove as much of the tumor as possible from the breast. However, sometimes cancer cells remain behind in the breast or in other areas of the body. Adjuvant treatments may help get rid of these remaining cells.

Radiation

Radiation therapy uses beams of energy, such as X-rays, that can damage cancer cells. This treatment can help reduce the chance that a tumor comes back. For people with HER2-positive breast cancer, the combination of targeted therapy, surgery, and radiation often works well to remove the cancer and keep it from coming back.

Chemotherapy

Individuals with HER2-positive breast cancer may also receive chemotherapy treatments. While targeted therapies are designed to recognize specific types of cancer cells, chemotherapies are medications that kill all cancer cells.

If you have HER2-positive breast cancer, you may receive chemotherapy medication along with targeted therapy. For example, you may take the chemotherapy drug Xeloda (capecitabine) along with kinase inhibitors to treat advanced cancer or as a second-line therapy. Chemotherapy and HER2-targeted therapy drugs are sometimes given together in regimens such as:

• TCHP — Taxol (paclitaxel) or Taxotere (docetaxel), Paraplatin (carboplatin), Herceptin (trastuzumab), and Perjeta (pertuzumab)
• TH — Taxol (paclitaxel) and Herceptin (trastuzumab)
• AC-TH — Adriamycin (doxorubicin), Cytoxan (cyclophosphamide), Taxol (paclitaxel) or Taxotere (docetaxel), and Herceptin (trastuzumab)

Hormone Therapy

HER2 is just one of several genetic changes a breast cancer cell may have. Breast tumors also may contain the estrogen receptor (ER) or progesterone receptor (PR) proteins. ER and PR are types of hormone receptors. Cancer cells that have either of these proteins use hormones (chemicals in the body that act as messengers) in order to grow. Hormone therapy can block these hormones, starving the cancer cells and making it difficult for them to grow.

If you have breast cancer that is both HER2-positive and hormone receptor-positive (has either ER or PR), then you may receive both targeted therapies and hormone therapies. Hormone therapy medications include Soltamox (tamoxifen) and aromatase inhibitors. Hormone therapy may be given before or after surgery, alone or with other treatments. This type of medication may be taken for five to 10 years.

Clinical Trials

New treatments are continuously being studied in clinical trials. If you’d like to know about other possible treatment options, ask your doctor about participating in a cancer research study. Clinical trials for breast cancer may offer access to treatments that are not widely available. Treatment provided in clinical trials may be free or lower in cost.

Partnering With Your Doctor

Shared decision-making is a process by which you and your doctor work together to decide on the best treatment plan for you. Your role in shared decision-making is to share your goals for treatment as well as your concerns and personal values, and ask questions about anything you don’t understand. Your doctor’s role is to take your preferences into consideration, and help you learn more about your condition and treatment options. Your doctor will answer questions and help you weigh the potential risks and benefits of each option. Together, you will decide on the best cancer treatment plan for you. Shared decision-making is considered vital to high-quality cancer care, and it has been shown to improve patient satisfaction.

Sticking With Your Treatment Plan

After you and your doctor decide on a treatment plan, it is important to follow your doctor’s directions. Keep taking the medication exactly as directed, for as long as directed, even if you feel better. If you don’t follow your treatment plan, or you stop taking medication too soon, you may experience some negative effects:

• The treatments may not work as well.
• You may need to go to the doctor more often.
• You may have a higher chance of needing to go to the hospital.
• You may have a worse outcome.

If you experience difficulty sticking to your treatment plan for any reason, talk to your doctor first before making any changes. They may be able to help you manage side effects or overcome other problems.

Talk With Others Who Understand

MyBCTeam is the social network for people with breast cancer and their loved ones. On MyBCTeam, more than 54,000 members come together to ask questions, give advice, and share their stories with others who understand life with breast cancer.

Are you living with HER2-positive breast cancer? Share your experience in the comments below, or start a conversation by posting on your Activities page.