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FDA approves Aromasin for use in post-menopausal breast cancer patients (dateline November 22, 1999)

The U.S. Food and Drug Administration recently approved the drug Aromasin (generic name, exemestane) to treat advanced stage breast cancer in post-menopausal patients. The approval comes after the results of a large clinical trial were presented at the 35th annual meeting of the American Society of Clinical Oncology (ASCO). Researchers compared Aromasin to standard hormonal therapy (treatment with the drug, megestrol acetate) in patients who did not respond well to tamoxifen. Their results reveal that the use of Aromasin significantly reduces tumor progression and the overall mortality rate for advanced breast cancer.

Researchers studied 769 post-menopausal women with metastatic breast cancer (cancer that has spread past the breast and underarm lymph nodes) to determine whether the use of Aromasin had greater benefits than megestrol acetate. Not only did Aromasin reduce the mortality rate by 23% in women who were randomly selected to take the drug, but researchers discovered that Aromasin also delayed the overall progression of cancer (from 3.8 months in women who took megestrol acetate compared to 4.7 months in women who took Aromasin). 15% of women who took Aromasin also experienced a 50% reduction in the size of their tumors, and in some cases, Aromasin completely eliminated breast tumors.

Aromasin works by binding to the body’s aromastase enzyme, an enzyme responsible for producing the hormone, estrogen. Many breast cancer cells depend on estrogen to grow and multiply quickly. Once aromasin has binded to the aromastase enzyme, estrogen cannot be produced by the enzyme ever again. This lack of estrogen "starves" cancer cells, preventing them from growing.

Aromasin is currently FDA approved in tablet form only. The common dosage is one 25 mg tablet daily until treatment is completed. Typical side effects of Aromasin include:

  • Hot flashes
  • Nausea
  • Fatigue
  • Increased sweating
  • Increased appetite

In the clinical trial, 18.4% of women who took Aromasin experienced nausea and 13.4% had frequent hot flashes. The researchers also noted that 17.4% of women on Aromasin experienced undesirable weight gain compared to only 7.6% who took megestrol acetate.

Aromasin is a new method of treating Stage IV breast cancer in patients who do not show a response to the anti-cancer drug, tamoxifen. There is currently no cure for Stage IV (advanced) breast cancer and treatment focuses on relieving symptoms and extending a woman’s lifetime. According to the National Cancer Institute, approximately 10% to 20% of women with metastatic breast cancer survive the disease (achieve permanent remission). New medical advances such as the FDA’s approval of Aromasin offer hope in raising this survival rate.

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