Arimidex

Arimidex (chemical name: anastrozole) has been used for many years as a treatment for post-menopausal women with advanced disease that is hormone-receptor-positive. In October 2005, the FDA approved Arimidex for adjuvant use in women with early-stage, hormone-receptor-positive breast cancer. "Adjuvant" means it is used after your first cancer treatments, such as surgery, chemotherapy, and radiation.

Arimidex was the first aromatase inhibitor to be tested against tamoxifen for women with early-stage disease. The ATAC (Arimidex or Tamoxifen Alone or in Combination) trial began in 1999 and will continue until 2011. This large, worldwide study of women with early-stage breast cancer was designed to show whether Arimidex, tamoxifen, or a combination of Arimidex and tamoxifen is most effective in treating post-menopausal women with early-stage, hormone-receptor-positive breast cancer.

The ATAC study included more than 9,300 post-menopausal women who had just finished their first treatment (surgery with or without radiation or chemotherapy) for early-stage, hormone-receptor-positive breast cancer. The women were given either tamoxifen, Arimidex, or both. The researchers followed these women for at least five years. They noted side effects in each treatment group and how many women had breast cancers come back (in the same or the other breast), had breast cancers spread, or died.

Researchers will continue to follow these women for a total of 10 years. Here are the results of the study so far:

• Arimidex alone was significantly better than tamoxifen alone for:
  • reducing the risk of cancer coming back.
  • decreasing the risk of cancer spreading to other parts of the body.
  • lowering the risk of a new breast cancer developing in the other breast.
  • reducing the risk of dying of breast cancer.
• Arimidex alone was significantly more effective than tamoxifen and Arimidex together.
• Improvements were seen in women with any combination of hormone-positive receptors: estrogen-receptor-positive, progesterone-receptor-positive, or both.
• Women taking Arimidex had fewer menopausal symptoms and fewer cases of uterine cancer (cancer of the uterus), blood clots, or strokes. But women taking Arimidex had more joint aches and pains and more bone breaks.