Treatment Resistance to Metastatic Breast Cancer
- Breast cancer can be hormone-receptor positive; this type of cancer carries receptacles for hormones that stimulate it. Endocrine agents that interfere with hormones may fight this type of cancer.
Breast cancer can produce high levels of Human Epidermal Growth Factor Receptor 2 (HER2), a protein that makes the cancer very aggressive. The tumor may respond to drugs that target this protein.
If the cancer has neither receptors nor the HER2 protein, chemotherapy is usually the treatment of choice. - Advanced breast cancer typically metastasizes, or spreads, to bones, the liver or the lungs. It can spread to one, two or three of these areas. The treatment strategy you and your doctor attempt will probably involve specific therapy, such as radiation, for the site of the metastasis and whole body, or systemic, treatment using hormone therapy, chemotherapy and biotherapy, depending on the type of cancer you have.
- Breast cancers that require hormones to grow have estrogen receptors, progesterone receptors or both and respond to therapies that block or lower estrogen levels. Treatment in premenopausal women can include removal of the ovaries and drug therapies such as tamoxifen, toremifene and gonadotropin-releasing hormone antagonists. In postmenopausal women, the therapies of choice are tamoxifen, aromatase inhibitors, anti-estrogens, progestins, estrogen deprivations and high-dose estrogen. These therapies can be used alone or in combination.
- The intravenous drug trastuzumab and the oral medication lapatinib specifically target HER2, although in different ways. The drugs can be used alone or in combination.
- Systemic chemotherapy, administered intermittently or continuously, is often recommended for all women with metastatic disease. Bevacizumab, which interrupts the tumor's blood supply, depriving it of nourishment, can be used alone or in combination with chemotherapy to treat HER2-negative cancer.
- According to the Breast Cancer Research website, most cancers eventually become resistant to tamoxifen and aromatase inhibitors. The "Irish Medical News" reports that many cancers also develop a resistance to monoclonal antibody treatments such as trastuzumab and enzyme inhibitors such as lapatinib and to chemotherapy. Women with resistant disease may want to consider enrolling in a clinical trial.
- All breast cancer treatments have negative side effects. Your and your doctor will have to determine the best course of therapy to treat your disease and give you an acceptable quality of life.
