Metastatic breast cancer is rare (about six percent) on initial diagnosis. But approximately 30 percent of women who are diagnosed with earlier-stage breast cancer develop advanced or metastatic breast cancer, according to Joyce O'Shaughnessy, a medical oncologist specializing in breast cancer with Texas Oncology. Chemotherapy is the use of medications to kill cancer cells, according to the American Cancer Society. Although metastatic breast cancer is not curable, it is treatable and is commonly treated with hormone therapy (considered a type of chemotherapy) and/or chemotherapy, with or without targeted therapies (also considered a type of chemotherapy), according to the National Cancer Institute.
Hormone Therapy
Although many people do not think of hormone therapy as chemotherapy, it actually is a form of chemo, just not the traditional intravenous type. The American Cancer Society estimates that about two-thirds of breast cancers are estrogen-receptor positive, which means that estrogen fuels the growth of these tumors--even in post-menopausal women. If estrogen is blocked or the level of estrogen in the body is lowered, the growth of these breast cancers is slowed or stopped. These estrogen-blocking drugs include tamoxifen, fulvestrant (Faslodex), anastrozole (Arimidex) and exemestane (Aromasin), according to cancer.org.
Chemotherapy
Chemotherapy for breast cancer tends to be most effective when combination chemotherapy regimens are used, meaning when two or more drugs are used together, says cancer.org. The American Cancer Society lists some of these combinations, including: CMF (cyclophosphamide, methotrexate and 5-fluorouracil); CAF (cyclophosphamide, doxorubicin and 5-fluorouracil) and AC (doxorubicin and cyclophosphamide).
Targeted Therapies
Though targeted therapies are sometimes classified as separate from typical chemotherapy drugs, they are still medications used to fight cancer, which makes them a different kind of chemotherapy. Targeted therapies used in metastatic breast cancer include trastuzumab (Herceptin), lapatinib (Tykerb) and bevacizumab (Avastin). Trastuzumab and lapatinib are used in women whose breast cancer is HER2-positive (HER2 is a protein that fuels the growth of some breast cancers), and bevacizumab targets growth factors that help form new blood vessels, which cancer needs in order to grow, says cancer.org. Bevacizumab is typically used with the chemotherapy drug paclitaxel (Taxol), according to the American Cancer Society.
