Breast Cancer Medicines

These treatments use drugs to attack your cancer in various ways, and may be given if your cancer has spread beyond the breast.

Which Phase 1 and Phase 2 medications have the potential to increase survival for breast cancer? Dr. Levine discusses.


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).

RPCI Advantage

As part of our breast cancer care, a full-time pharmacist manages chemotherapy treatments for our breast patients. The pharmacist writes the chemotherapy treatment plan, assess medication lists for potential problems or duplication, monitors treatment for possible drug interactions and manages concurrent anticoagulant medicines.

Targeted Therapy

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.

Hormone Therapy

Dr. O’Connor explains the difference between hormone therapy and chemotherapy and how they are used to treat breast cancer patients.

For cancers that are estrogen-positive, drugs that lower or block the hormones can work against the cancer and/or 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 stop the ovaries from producing estrogen by preventing the pituitary gland in the brain from making LHRH.

Ovarian Suppression

Because the ovaries are the main source of estrogen in pre-menopausal women, treatment that shuts down the ovaries and stops estrogen production can be effective for some women. Ovarian suppression is typically accomplished with hormone therapy, using drugs such as leuprorelin (Lupron) or goserelin (Zoladex).