Chemotherapy used to be standard treatment for many patients. Now doctors can use genomic testing — analysis to reveal a tumor’s genetic activity — to identify some of the patients who won’t benefit, sparing them from side effects. Genomic testing can also indicate how likely a cancer is to come back.

For now, results of genomic testing are reliable only for patients with some forms of early-stage breast cancer. Your medical oncologist will talk with you about whether genomic testing makes sense for you and, if so, how the results can guide treatment decisions. Read more below.

Chemotherapy targets fast-dividing cells, a key trait of cancer cells. Different medications work in different ways. Some chemo medications prevent the cells from dividing, for example, and others trigger them to self-destruct.

Most chemo patients receive a combination of medications, called a regimen, to target cancer from different angles.

Most often, chemo medications are given in an IV drip called an infusion. Patients often receive chemo on an outpatient basis in two- or three-week cycles, with time off to recover. The number of cycles depends on the treatment regimen.

Some patients have a port, a small device implanted in the chest and connected to a large vein. This enables them to receive chemo or have blood drawn without the nurse hunting for a vein. The port is removed when it’s no longer needed.

Neoadjuvant chemotherapy: This chemotherapy is given before surgery to shrink the tumor. This can reduce the extent of surgery or shrink a tumor that’s too big to remove surgically. Neoadjuvant chemo can also help your doctor identify which medications work best on your cancer.

Adjuvant chemotherapy: This chemotherapy is given after surgery to kill any cancer cells that may remain. Adjuvant chemo can lower the risk that cancer will come back or spread to another part of your body.

For advanced cancer: For patients with breast cancer that has spread outside the breast and underarm lymph nodes (also called metastatic breast cancer), chemotherapy may be given to shrink or slow the growth of tumors or to control symptoms.

Hormone therapy can be effective if your cancer has receptors for the hormones estrogen and/or progesterone. If so, your cancer will be described as:

• Hormone receptor positive or
• Estrogen receptor positive and/or
• Progesterone receptor positive

If you don’t have any hormone receptors, hormone therapy won’t work. Hormone therapy is most often given to three types of hormone-receptor-positive patients:

• Those with early-stage cancer, to reduce the risk of cancer coming back.
• Those with advanced (metastatic) cancer to shrink or slow tumor growth.
• Those at high risk of breast cancer but not diagnosed, to lower their risk.

Hormone therapy is also sometimes used to shrink a tumor before surgery. 

Estrogen circulating in the body can bind to breast cancer cell receptors, like keys fitting in locks, and tell the cells to divide and grow. Most hormone therapies work by blocking the receptors — like jamming the lock to keep estrogen out — or by lowering the amount of estrogen in the body.

Most types are daily pills taken for five or more years. A type called "ovarian ablation" for premenopausal women uses surgery or injected medication. Patients with advanced or recurrent hormone-positive cancer sometimes receive monthly injections. 

Receptor blocking: This type works by binding to receptors, keeping out estrogen. Medications include tamoxifen, taken as a daily pill or liquid (brand names Nolvadex and Soltamox).

Estrogen blocking: This type targets the body’s ability to make estrogen by blocking a needed enzyme called aromatase. Medications called aromatase inhibitors are taken as daily pills. They are: anastrozole (brand name Arimidex), letrozole (Femara) and exemestane (Aromasin).

Ovarian disrupting: In premenopausal women, most estrogen comes from the ovaries. A hormone therapy called ovarian ablation can shut down estrogen production. The ovaries can be surgically removed or disabled temporarily with injected medications.

When it’s given: Like chemotherapy, hormone therapy can also be:

• Neoadjuvant, to shrink the tumor before surgery. This is less common with hormone therapy than other therapies.
• Adjuvant, to lower the risk of cancer returning.
• For advanced cancer, to slow growth.

Targeted therapies for breast cancer are available for two types of patients:

• Those whose cancer is HER2 positive, meaning their cancer cells have proteins, or receptors, that promote cancer growth. Read more about HER2 receptors on the Understanding Breast Cancer page.
• Those with hormone-receptor-positive breast cancer.

Different medications target different pathways. Trastuzumab (Herceptin), for example, binds to HER2 receptors to prevent them from receiving signals to grow and multiply. Other medications help hormone therapies work better by disrupting cancer cell functions.

Most medications that target HER2 receptors are given by IV. Early-stage patients who receive adjuvant Herceptin, for example, receive weekly infusions for a year.

Medications for hormone-receptor-positive patients are daily pills and are generally used in combination with hormone therapy.

HER2 medications: These medications generally take advantage of HER2 receptors, either by blocking them so cancer cells can’t receive instructions to divide and grow, or by using them to deliver instructions that disrupt cell functions. IV medications include Herceptin, pertuzumab (brand name Perjeta) and ado-trastuzumab emtansine (Kadcyla). Another type, a daily pill called lapatinib (Tykerb), has small molecules that enter cancer cells to disrupt cell functions.   

Hormone receptor positive medications: Medications that help hormone therapies work better do so by inhibiting cancer cell functions. Palbociclib (Ibrance), for example, is a CDK 4/6 inhibitor that disrupts a protein that controls cell growth and division. Everolimus (Afinitor) is an mTOR inhibitor that targets a protein that controls cell growth and survival.

When it’s given: Targeted therapies can also be:

• Neoadjuvant, to shrink the tumor.
• Adjuvant, to lower the risk of cancer returning.
• For advanced cancer, to slow growth.

Immunotherapy may help some patients with breast cancer types including:

• Triple-negative breast cancer (TNBC)
• PD-L1-positive breast cancer
• HER2-positive breast cancer
• dMMR breast cancer

The types of immunotherapy used to treat breast cancer are:

• Immune checkpoint inhibitors: Some cancer cells grow tiny protein chains on their surface that help them hide from the immune system. The chains are like key cards that allow cancer cells through a checkpoint. Immunotherapy drugs break the chains. That scrambles the key cards and sounds the alarm. The alarm helps the immune system see and destroy the cancer cells.
• Immune targeted therapies: These drugs combine targeted therapy and immunotherapy. They lock onto targets on the surface of cancer cells, and block signals that tell the cells to grow. They also send a signal to the immune system to destroy the cancer cells.

Immunotherapy drugs are usually given as an infusion, or drip. They may also be given as pills.

Immunotherapy is often given with other types of therapy, like chemotherapy or surgery.

HER2 medications: These medications generally take advantage of HER2 receptors, either by blocking them so cancer cells can’t receive instructions to divide and grow, or by using them to deliver instructions that disrupt cell functions. IV medications include Herceptin, pertuzumab (brand name Perjeta) and ado-trastuzumab emtansine (Kadcyla). Another type, a daily pill called lapatinib (Tykerb), has small molecules that enter cancer cells to disrupt cell functions.   

Hormone receptor positive medications: Medications that help hormone therapies work better do so by inhibiting cancer cell functions. Palbociclib (Ibrance), for example, is a CDK 4/6 inhibitor that disrupts a protein that controls cell growth and division. Everolimus (Afinitor) is an mTOR inhibitor that targets a protein that controls cell growth and survival.

When it’s given: Targeted therapies can also be:

• Neoadjuvant, to shrink the tumor.
• Adjuvant, to lower the risk of cancer returning.
• For advanced cancer, to slow growth.