A hormone therapy drug, called exemestane, may be beneficial against advanced breast cancer in post-menopausal women for whom previous hormone therapy has not been successful. This finding, according to researchers from several medical centers, indicates that this agent may be an additional treatment option for women whose cancer uses estrogen to grow.
Breast cancer is characterized by the presence of cancer cells in the tissue or ducts of the breast. Depending on the stage of disease, treatment options may include surgery, chemotherapy, radiation therapy, and/or hormone therapy. For women with advanced disease that has spread to other parts of the body, the goal of treatment is usually to relieve the symptoms of disease and to prolong survival time.
Hormone therapy is advantageous for many women in whom the breast cancer cells use a hormone called estrogen to grow (called
estrogen receptor-positive breast cancer). Women who have already gone through menopause (sometimes called
post-menopausal) who have estrogen receptor-positive breast cancer may benefit from hormone therapies, such as tamoxifen or megestrol acetetate, which help to stop the cancer from growing. However, additional sources of estrogen in the body must also be considered. An enzyme called aromatase can convert a hormone in the body (called androstenedione) into an estrogen compound, which can then further feed any estrogen receptor-positive cancer cells. A new drug, called
exemestane, inhibits this aromatase enzyme, and therefore stops the body from producing the estrogen compound. Researchers recently studied this drug in post-menopausal women who had estrogen receptor-positive disease.
Ninety-one post-menopausal women with advanced breast cancer were treated with exemestane. All had estrogen receptor-positive disease in which treatment with both tamoxifen and megestrol acetate had been unsuccessful. The results of exemestane therapy showed 4 complete responses and 8 partial responses. The success rate, including disease that showed no further progression, was 30%. The side effects from the treatment were minimal.
The researchers concluded that exemestane is a safe drug that should be considered for post-menopausal persons with advanced breast cancer for whom hormone therapy with tamoxifen and megestrol acetate is unsuccessful. Postmenopausal women with advanced breast cancer may wish to talk with their doctor about the risks and benefits of exemestane, or of participating in a clinical trial in which other new treatments are being studied. Sources of information on ongoing clinical trials that can be discussed with a doctor include a comprehensive, easy-to-use service provided by the National Cancer Institute (cancer.gov) and the Clinical Trials section and service offered by Cancer Consultants.com (www.411cancer.com). (Journal of Clinical Oncology, Vol 17, No 11, pp 3418-3425, 1999)