Had Surgery And Radiation For Breast Cancer. Prescribed Aromasin. Having Side Effects. What Is The Cause?

Posted on Wed, 20 Nov 2013

Medically reviewed by Ask A Doctor - 24x7 Medical Review Team

Wed, 20 Nov 2013 Answered on

Wed, 11 Dec 2013 Last reviewed on

Question : My wife, 71 years old, has undergone surgery and radiation for breast cancer (level 1, IDC, ER-pos, node-neg). Her oncologist started her on Aromasin shortly after the radiation. I've looked at all the material from Pfizer and talked to Pfizer and the message from them is clear...they have only done trials on women who had 2-3 years of Tamoxifen treatment, then were switched to Aromasin. They have done no studies on the implications of going directly on Aromasin. They say it's strictly a judgement call for the oncologist to go directly to Aromasin. The Pfizer trials showed a 3-4% reduction in bone density after two years (much higher than Tamozifen) so we're concerned about the effect after five years of Aromasin which is what the oncologist is recommending. The side effects she's experiencing on Aromasin are unpleasant and if they continue will not be acceptable for 5 years. Of course, there's also the question of what the implications would be of switching to Tamoxifen now that she's been on Aromasin for 9 months. Any comments would be appreciated.

Answered by Dr. K. Harish (20 hours later)

Brief Answer: Discuss with your oncologist Detailed Answer: You have understood it right. The side effects are because it lowers the estrogen production in the body. Compared to other aromatase inhibitors (drugs like anastrozole) the reduction in bone density is probably acceptable. Please understand that all drugs used based on Esrtogen and progesterone receptor status act against estrogen or its action. In that sense, any/all of these drugs result in estrogen withdrawal symptoms (crudely describing it as menopausal symptoms). Some side effects are bound to be there irrespective of which durg is used. If they reach unacceptable levels, please check with your doctor. Four drugs are commonly used in this scenario viz, Tamoxifen, Letrozole, Exemestane and Anastrozole. Taxmoxifen is the drug used since late 70's and hence has the longest follow up. Others have been used since late 90's. Hence we do not have a very long term follow up of the newer drugs although the oncologic outomes have been promising. it should also be understood that only ONE of the four drugs would be administered and the choice depends on pre/post menopausal amongst many other factors. There must be a reason why your wife has been started on exemestane (aromasin) instead of other drugs. Please check with your oncologist since he/she would know the patient in detail.

Above answer was peer-reviewed by : Dr. Yogesh D