Patients' Perspectives:
Tamoxifen and Femara

A number of patients who were diagnosed with hormone-receptor positivie, primary breast cancer and who have not developed metastatic breast cancer are beginning to use Femara (letrozole) rather than Tamoxifen (nolvadex) as a prophylactic measure against recurrence.  The manufacturer of Femara, Novartis, currently has clinical trials in place to compare these two medications in the primary setting.  However, the current trials include only patients diagnosed at Stages I, II, and IIIA.  A number of patients diagnosed at Stage IIIB and particularly some who were initially diagnosed with inflammatory breast cancer are also beginning to take this medication.  It is not our place to recommend or not to recommend the use of any particular medication or treatment plan.  But, we do believe patients should have an outline of the issues involved so they can do their own research in order to make as informed a judgment as possible.

• Research on Femara reported at the 2000 San Antonio Breast Cancer Symposium show that it is more effective than Tamoxifen in controlling metastatic disease.
• Femara has not yet been shown to be as effective as Tamoxifen in non-metastatic disease settings, i.e., if you don't have distant metastases, it's not been studied yet.
• Femara is presently in trials to supply this information, but the present trials do NOT include Stage IIIB patients.  Particularly, inflammatory breast cancer patients, who are normally diagnosed at Stage IIIB, are not included.  The present trials are only for patients having been diagnosed with primary breast cancer at Stages I, II, or IIIA.
• Femara works differently than Tamoxifen which "fills in" the estrogen receptor much in the way a key goes into a lock.  One issue here is that the fit is not tight, something like putting the wrong key into the lock.  Even though the key still goes into the lock, it won't turn once it is in there.
• Femara is called an aromatase inhibitor.  It works by preventing the formation of estradiol (what estrogens become before they go floating around trying to find a home).  The reasoning here is that, if you don't have estrogens available in the body, they can't be converted to the forms that allow it to hook into any estrogen receptors that may still be around on stray tumor cells.
• Estrogen itself appears to have significant, positive effects on the prevention of heart disease and on the prevention of osteoporosis such that the potential impact of these two conditions needs to be considered for any patient who is in the process of deciding between Tamoxifen and Femara.
• ALL of the research that has been done to date is on post-menopausal women and the current trials are for post-menopausal women.  So, patients who are pre-menopausal may want to consider this particular distinction.

Paul E. Goss, Kathrin Strasser (2001)  Aromatase Inhibitors in the Treatment and Prevention of Breast Cancer. Journal of Clinical Oncology.  19:3 (February), 881-894

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