Medical treatments use drugs to attack your cancer in various ways, and may be part of your treatment if your cancer has spread beyond the breast and/or if your cancer tests positive for estrogen receptors, progesterone receptors and the HER2 protein. These treatments are also called systemic therapies because the drugs travel through your whole body system.
Hormone therapy for breast cancer
For cancers that are estrogen-positive, drugs that lower or block estrogen, or suppress the ovaries, can reduce the body’s estrogen, which the cancer needs in order to grow. These drugs work against the cancer and help to prevent its recurrence. This treatment option depends on your personal diagnosis and whether you have completed menopause. Typically, women continue hormone therapy for at least five to 10 years.
- Anti-estrogen drugs. These drugs, such as tamoxifen, toremifene and fulvestrant block the estrogen receptors on the cancer cells.
- Aromatase inhibitors. These drugs, such as anastrozole, letrozole and exemestane, decrease estrogen in the body by blocking the action of the enzyme aromatase from converting androgen to estrogen.
- Luteinizing hormone-releasing hormone (LHRH) agonists. These drugs such as leuprorelin (Lupron) or goserelin (Zoladex) suppress estrogen production in the ovaries by preventing the brain’s pituitary gland from making LHRH.
Chemotherapy for breast cancer
In general, chemotherapy drugs work against cancer cells by killing cells that are growing and multiplying rapidly. Many different chemotherapy drugs are effective for breast cancer breast cancer and they work in different ways. Your oncologist will choose the drug — or combination of drugs — that match your personal situation. They may be given intravenously (IV) or taken orally (by mouth). Chemotherapy is typically given in cycles of several treatment days followed by days of rest to allow your body to recover.
Targeted therapy for breast cancer
Targeted therapy drugs are able to selectively find cancer cells by homing in on a specific feature or substance that's found only on the cancer cells, leaving normal cells alone. Some targeted therapies for breast cancer include:
- Monoclonal antibodies. Drugs such as trastuzumab and pertuzumab use antibodies made in the laboratory from an immune cell. For women with HER2 positive breast cancer, these antibodies attach to substances on the cancer cell, killing it, blocking its growth, or preventing it from spreading. Monoclonal antibodies can also carry toxins, radioactive substances or other drugs directly to the cancer cells.
- Tyrosine kinase inhibitors. Drugs such as lapatinib block the signals needed for tumors to grow.
- Other targeted drugs such as CDK4/6 inhibitors, PARP inhibitors, mTOR inhibitors and more, work against breast cancer by blocking certain proteins or signals that the cancer cells need to grow or survive.
Immunotherapy for breast cancer
Immunotherapy is a class of cancer drugs that aims to activate your body’s own immune system to fight the cancer. Cancer grows in the body in part because the immune system has switched off. Immunotherapy drugs look to block the off switches and turn the immune system back on again. One type of immunotherapy used for breast cancer is called a checkpoint inhibitor:
- Checkpoint inhibitors. This type of immunotherapy works to block a protein on the cancer cells called PD-1 which interacts with another protein called PD-L1. This interaction effectively “applies the brakes” to the immune system, stopping it from killing the cancer cells. By blocking the PD-1 protein, the interaction doesn’t occur and “releases the brakes,” allowing the immune system to do its job. Pembroluzumab (Keytruda) is one checkpoint inhibitor approved for use in breast cancer.
Novel anti-cancer agents
Cancer researchers around the world and here at Roswell Park work every day to discover how to create new drugs, substances, and other agents to fight breast cancer. The most promising options are available to patients through clinical trials.