Estrogen, a sex steroid synthesized mainly by the ovaries, affects several bodily processes. Women of reproductive age have the highest levels of this natural hormone. Excessive amounts, however, can create a syndrome known as estrogen dominance. This medical condition may lead to breast and endometrial cancer. Anti-estrogenic medications, known as selective estrogen receptor modulators and aromatase inhibitors, can correct these imbalances. Such drugs, however, have positive and negative effects on the women using them.
According to a 2010 review published in the medical journal, "Core Evidence," prolonged exposure to estrogenic drugs may cause endometrial cancer in women. Raloxifene, a selective estrogen receptor modulator, may prevent the development of cancer by selectively blocking estrogen uptake. This drug, however, can also inhibit the positive effects of estrogen on bone health. A newer drug, lasofoxifene, may rectify that problem. This SERM prevents the loss of bone density in postmenopausal women, and reduces bone breaks, as well. Lasofoxifene use is, in general, safe, but may increase the risk of blood clots.
Estrogen receptor blockers, like tamoxifen, may help prevent cancer. Yet patients with cancer often experience depression, and SERMs can negatively interact with anti-depressant medications. A 2010 investigation presented in the "British Medical Journal" looked at the impact of concurrent use of anti-estrogenic and antidepressant drugs. Women taking tamoxifen and paroxetine had at least a 24 percent greater risk of mortality than women taking tamoxifen and any other antidepressant. That's because paroxetine is a type of antidepressant that blocks a specific enzyme called CYP2D6. This enzyme normally increases tamoxifen's half life. Women who need to use both medications should, therefore, choose an antidepressant drug that does not interfere with estrogen blockers.
Tamoxifen use also impacts cognitive performance on learning and memory tasks. A 2010 experiment described in the "Journal of Oncology" tested postmenopausal women using estrogen blockers to treat their breast cancer. Results indicated that, relative to controls, one year of tamoxifen treatment negatively affected verbal memory and planning skill. Another type of estrogen blocker, exemestane, did not alter performance. Exemestane prevents the accumulation of aromatase, an enzyme critical for the production of estrogen. Thus, newer medications may provide ways to inhibit estrogen without causing as many adverse reactions.
Aromatase inhibitors provide some advantages over SERMs, yet they also have their own side effects. A 2010 study noted in the periodical, "Clinical Breast Cancer" evaluated the impact of estrogen blockers in women with breast cancer. Anti-estrogen therapy effectively treated the cancer, but increased symptoms of rheumatic disorders such as carpal tunnel syndrome. Even worse, these disorders affected a patient's ability to function. Women, therefore, must carefully consider the advantages and disadvantages of anti-estrogenic drugs.