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 whether your cancer tests positive for estrogen receptors, progesterone receptors and the HER2 protein.
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 can both work against the cancer and help to prevent recurrence. This choice 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.
Drugs and other anti-cancer agents circulate the body eliminating cancer cells. Many different drugs work against 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).
A drug can target or change the activity of a specific feature or substance on the cancer cell, 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.