Arimidex More Effective Than Tamoxifen for Postmenopausal Women

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A study provides another year of results for the ATAC (Arimidex and Tamoxifen Alone or in Combination) trial. The results continue to show that 5 years of Arimidex (chemical name: anastrozole) is better than 5 years of tamoxifen as the first hormonal therapy for postmenopausal women with early-stage hormone-receptor-positive breast cancer. Arimidex is better than tamoxifen for:

  • increasing the time before the cancer comes back
  • reducing the risk of the cancer spreading to other parts of the body
  • reducing the risk of a new cancer developing in the other breast

It appears that even after 5 years of treatment is done, the benefits of Arimidex over tamoxifen continue and even increase.

Still, there is no real difference in overall survival time between the two medicines.

This latest study report also showed a result that hadn't been seen before. The higher risk of broken bones associated with Arimidex disappeared after the women stopped taking Arimidex.

Arimidex is an aromatase inhibitor, a medicine that lowers the amount of estrogen in the body. This means that less estrogen reaches bone cells, which can lead to bone thinning and weakening and an increased risk of broken bones. This side effect of Arimidex is the most troubling issue for some women. Doctors may recommend that women with osteoporosis take tamoxifen rather than Arimidex because of this possible side effect.

The women in the ATAC trial now have been followed for about 8 years -- 5 years while they took ether Arimidex or tamoxifen or both, and 3 years after they stopped taking the medicine. The ATAC trial began in 1999 and the researchers will continue to follow the women in the study until 2011.

While the evidence keeps building that aromatase inhibitors are the best hormonal therapy to start with after initial breast cancer treatment for postmenopausal women diagnosed with early-stage, hormone-receptor-positive breast cancer, tamoxifen is still a good choice. For a number of reasons, including side effects and cost, tamoxifen may be a better choice for some women.

When you're deciding on a treatment plan, keep two things in mind:

  • Every woman responds differently to treatment. What works for someone else may not work for you and what works for you may not work for someone else.
  • Your treatment plan is not written in stone. You can always change treatments if another treatment has greater benefits and fewer side effects.

If you're a postmenopausal woman being treated for hormone-receptor-positive, early-stage breast cancer, talk to your doctor about the pros and cons of aromatase inhibitors compared to tamoxifen. If you're currently taking tamoxifen, discuss whether switching to an aromatase inhibitor makes sense for you. Together, you can decide on a treatment plan that is best for YOU.

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