Aromatase Inhibitors: Startling New Study Shows Dramatic Reduction in Recurrence Rates

PJ Hamel Health Guide
  • If you finished taking tamoxifen for ER-receptive breast cancer even as long as 7 years ago, you might be able to do something right now to cut your risk for another bout of  cancer by as much as 82%.


    The March 10 edition of the Journal of Clinical Oncology features results of a study that could impact millions of breast cancer survivors. And the news is good: the aromatase inhibitor letrozole (a.k.a. Femara; and, by common assumption, its fellow AIs Aromasin and Arimidex) lowers the risk of breast cancer recurrence, metastasis, and new breast cancer in survivors by as much as a whopping 82%.

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    Perhaps even more exciting, however, is that this reduction benefit is felt even if treatment with an AI isn’t begun till up to 12 years after diagnosis—and perhaps even longer. Studies are continuing to identify just how long the protective effect of AIs remains strong (as well as how far past diagnosis they can be started), and still be expected to lower cancer risk. 

    Lead researcher Dr. Paul E. Goss, Director of Breast Cancer Research at Massachusetts General Hospital, noted in the Journal article, “What our results have shown for the first time in breast cancer treatment history is that taking an anti-estrogen anywhere along that line appears to have a dramatic reduction in the risk of recurrence.” Added Nancy U. Lin and Eric P. Winer of Boston’s Dana-Farber Cancer Institute, in an editorial accompanying the article, the results of the study represent a “paradigm shift” in breast cancer treatment.

    This is indeed big news for the approximately 70% of us whose cancer is estrogen-receptive. Most of us have treated our ER-receptive breast cancer with a combination of surgery, radiation and/or chemo, and tamoxifen. Some of us have switched to an AI after 2 to 5 years of tamoxifen. And, as more proof of AIs’ effectiveness has accumulated in the past 5 years, some of us may have even skipped tamoxifen entirely, and started right out on an AI, directly after finishing radiation or chemo.

    But up till now, it appeared that women who completed their 5 years of tamoxifen before AIs were commonly prescribed had missed the boat on this extra measure of protection. Pre-AI, five years of tamoxifen was the limit of what our doctors could do for us. Now, however, women who stopped taking tamoxifen as long as 7 years ago could see a significant reduction in their recurrence risk, going forward, if they start taking an aromatase inhibitor. This risk reduction is 60% for recurrence, 61% for metastasis (recurrence outside the breast), and 82% for new cancer in the opposite breast.

    And the downside? (There’s always some downside, right?) AIs can have some fairly difficult side effects, including enough joint and bone pain that some women are unable to take them. And, they increase your risk of osteoporosis and bone fractures. Weigh that against the 60%-80% reduction in your risk of recurrence, however, and you may decide the possible side effects are worth it.


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    "We believe every patient who has previously taken tamoxifen should discuss the findings of this study with her oncologist. Our results suggest if you take anti-estrogen, aromatase inhibitor therapy at any point of diagnosis, it is going to impact your chances of not experiencing a recurrence," Goss noted.

    Was your breast cancer ER-receptive? Did you take tamoxifen? Are you post-menopausal? Are you currently not taking Aromasin, Femara, or Arimidex? If the answer to those four questions is yes, this exciting news is definitely something you should bring up with your oncologist.

Published On: March 12, 2008