09/23/2009 - Articles

Breast cancer drugs benefits, risks, examined

By: Susan Aldridge, medical journalist, PhD


Breast cancer is the second most commonly diagnosed cancer in women (after skin cancer) and leads to more than 40,000 deaths a year, with 190,000 new cases diagnosed. 

Breast cancer can be treated, and recurrence prevented, by the use of various drugs.  But they also have various side effects which ought to be taken into account before being prescribed in breast cancer.  Tamoxifen, raloxifene and tibolone are now reviewed for their benefits and risks in breast cancer by the Agency for Healthcare Research and Quality (AHRQ) in a new report. All three drugs are often prescribed to women who have a family history of breast cancer to reduce risk or after treatment to prevent recurrence. 


The AHRQ review found that all three medications do significantly reduce invasive breast cancer in midlife and for the older woman. But benefits and adverse effects vary with the drug and the patient herself. It is the first direct comparison between the three drugs so it will be of great value to those advising women with a risk of breast cancer.


Tamoxifen is a selective estrogen receptor modulator (SERM) which is used primarily for treatment of breast cancer rather than prevention.  Raloxifene, another SERM, is used mainly to prevent and treat osteoporosis, but was approved by the US Food and Drug Administration (FDA) for breast cancer risk reduction in 2007.  Tibolone is not yet FDA approved but is used elsewhere for menopausal symptoms and osteoporosis.  All three drugs reduce breast cancer risk but have side effects. Tamoxifen causes flushing and sweats (vasomotor symptoms) and vaginal dryness. Raloxifene is linked to vasomotor symptoms and tibolone causes vasomotor symptoms. 


Also, tamoxifen may increase risk of endometrial cancer, compared to the other two drugs.  Both it and raloxifene may increase the risk of blood clots and tibolone increases stroke risk.  But if you are at risk of breast cancer, maybe the benefit of these drugs would outweigh potential adverse effects.  The AHRQ therefore calls for more research to identify those women who have most to gain, and least to lose, from taking any of these three drugs to reduce breast cancer risk.


AHRQ Comparative Effectiveness of Medications to Reduce Risk of Primary Breast Cancer in Women.15th September 2009 www.effectivehealthcare.ahrq.gov


Created on: 09/23/2009
Reviewed on: 09/23/2009

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