Tamoxifen, often sold as Nolvadex, affects the body's estrogenic system. It blocks estrogen binding in the breast and promotes binding elsewhere. Doctors prescribe tamoxifen to treat breast malignancies because cancer cells need estrogen to develop. Athletes take Nolvadex to prevent the unwanted appearance of breast tissue caused by using steroids. While typically effective, this medication causes side effects. Alternative drugs, including aromatase inhibitors, provide more positive results with fewer negative reactions.
Letrozole
A newer drug letrozole, also known as Femara, offers a viable alternative to tamoxifen. A 2005 review published in Clinical Therapeutics looked at studies testing both tamoxifen and letrozole. Women with breast cancer using Femara had less mortality risk than women using Nolvadex. This finding occurred whether the women initially started treatment with letrozole or switched from tamoxifen to letrozole during therapy. Intake of Femara also caused fewer side effects, and women preferred using letrozole.
Anastrozole
Another newer medication called anastrozole provides some benefits over tamoxifen as well. According to the 2005 review described above, this drug, sold as Arimidex, is also more effective than Nolvadex for treating breast cancer. A 2003 study presented in the journal Cancer confirmed this finding in women with endometrial cancer. The latter study also showed that patients preferred anastrozole over tamoxifen because it caused fewer side effects. Women taking Arimidex experienced fewer cerebrovascular events, vaginal discharges and hot flashes than those taking Nolvadex.
Exemestane
A third type of aromatase inhibitor called exemestane is sold as the drug Aromasin. Using this medication increases the survival rate of cancer patients relative to using Nolvadex. A 2004 report offered in the New England Journal of Medicine compared tamoxifen and exemestane in women with breast malignancies. Switching to Aromasin reduced the risk of mortality by 32 percent. During five years of use, 20 women died while taking Nolvadex whereas 9 died while taking Aromasin. Patients using either drug rarely reported side effects. More striking, however, is the finding that the positive effects of exemestane persisted for five years after endocrine therapy had ended. According to a follow-up study published in the periodical Lancet, 261 women died in the Nolvadex group whereas 222 died in the Aromasin group over the combined 10-year span.
Mifepristone
The drug mifepristone, trade name Mifeprex, affects the body's progesteronic system. It can also serve as a substitute for tamoxifen in certain medical conditions. A 2006 experiment described in the periodical Cancer Investigation tested mifepristone in patients with benign tumors called meningiomas. When surgeons cannot remove these tumors, endocrine therapy may effectively treat them. In the study, Mifeprex reduced tumor volumes and caused behavioral improvements as well. It did, however, produce endometrial polyps in some patients. While of concern, these polyps were considered less problematic than the endometrial cancer often seen with tamoxifen use.
References
- "Clinical Therapeutics"; Are All Aromatase Inhibitors the Same? A Review of Controlled Clinical Trials in Breast Cancer; J. Berry; November 2005
- "Cancer"; Anastrozole Alone or in Combination with Tamoxifen versus Tamoxifen Alone for Adjuvant Treatment of Postmenopausal Women with Early-Stage Breast Cancer: Results of the ATAC (Arimidex, Tamoxifen Alone or in Combination) Trial Efficacy and Safety Update Analyses; M. Baum et al.; Nov. 1, 2003
- "New England Journal of Medicine"; A Randomized Trial of Exemestane after Two to Three Years of Tamoxifen Therapy in Postmenopausal Women with Primary Breast Cancer.; R. C. Coombes et al.; March 11, 2004
- "Lancet": Survival and Safety of Exemestane Versus Tamoxifen after 2-3 Years' Tamoxifen Treatment (Intergroup Exemestane Study): A Randomised Controlled Trial; R. C. Coombes et al.; Feb. 17, 2007
- "Cancer Investigation"; Long-Term Administration of Mifepristone (RU486): Clinical Tolerance during Extended Treatment of Meningioma; S. M. Grunberg et al.; December 2006
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