Benefits of Aromatase Inhibitors After 5 Years of Tamoxifen

Learn about the latest breast cancer research on the benefits of using aromatase inhibitors after completing 5 years of tamoxifen therapy.

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David A. Margileth, M.D.: There was a trial mainly conducted in Canada called the MA.17 trial where they took postmenopausal patients who had completed five years of tamoxifen and randomized those patients to take no further therapy or five years of an aromatase inhibitor.

What they found was that at about year eight or year nine, there was a benefit to patients that took the additional aromatase inhibitor.  This benefit was about 6% and the majority of that benefit was in patients who had lymph node-positive disease.

This trial has become a little outdated in that the most current approach to post menopausal patients would be to begin not with tamoxifen but with an aromatase inhibitor which brings up the issue of 10 years versus 5 years of an aromatase inhibitor.

But over the past year or two there have been a number of postmenopausal patients who are coming off five years of tamoxifen for which that question is appropriate.  My general approach has been in the patients with low grade or lymph node-negative breast cancer to not proceed with five years of an aromatase inhibitor, but patients with large tumors or poor prognostic factors or patients with lymph node-positive disease to consider adding five years of an aromatase inhibitor to the five years of tamoxifen.

Dr. David A. Margileth practices medical oncology at St. Joesph Hospital in Orange, CA specializing in oncology, hematology, and internal medicine (board certified). His selected area of interest is breast cancer. Dr. Margileth graduated from Baylor College of Medicine in 1971 and has since spent time treating patients at the National Cancer Institute and Methodist Hospital in Houston, TX.
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