
<b>Non Steroidal Reversible Aromatase Inhibitors. 
letrozole (Femara) anastrozole (Arimidex) vorozole (Rizivor) and others </b> 

<b>Simplified Mechanism of Action</b>
Ovaries make the estrogen for women's bodies until menopause.
After menopause, the only source of estrogen in the body is that made by aromatase enzymes. 
Aromatase Inhibitors prevent the aromatase from making estrogen.

<b>Mechanism of Action</b>
The new generation of potent steroidal and nonsteroidal inhibitors of the enzyme aromatase act by decreasing estrogen production throughout the body in postmenopausal women. Aromatase, a cytochrome P-450 enzyme that catalyzes the conversion of androgens to estrogens, is the major mechanism of estrogen synthesis in the post-menopausal woman. 
Inhibition of aromatase, the last step in estrogen synthesis, provides a way of treating hormone-dependent breast cancer in older patients. Aminoglutethimide was the first widely used aromatase inhibitor but had several drawbacks. Newer agents are considerably more selective, more potent, less toxic and easier to use. The newly developed, orally administered, nonsteroidal competitive inhibitors, such as anastrozole (Arimidex), letrozole (Femara), and vorozole (Rizivor), are a thousand times more potent inhibitors of aromatase than is aminoglutethimide. Besides the competitive aromatase inhibitors anastrozole, letrozole and vorozole there are the irreversible inhibitors 4-OH androstenedione and exemestane. 

Either anastrozole (1.0 mg/d) or letrozole (2.5 mg/d) are safe and effective in the management of hormone-dependent breast cancer in post-menopausal women failing antiestrogen therapy and are now recommended following Tamoxifen failure. In this setting they showed a trend toward improved response duration and survival. They also produced less weight gain and fewer cardiovascular and thromboembolic side effects, replacing the routine use of megestrol acetate in this setting. Letrozole [Femara] and anastrozole (Arimidex) are NOW sometimes being prescribed for hormone receptor positive LMS by doctors at sarcoma centers.

<b>Anti-Hormone Medication and Estrogen Receptor Positive [ER+] LMS</b>
These agents will not shrink LMS tumors, but either might slow tumor growth or at least prevent growth stimulation of the ER+ tumor by estrogen.

<b>AntiHormone Therapy and Cognition</b>
The incidence of Alzheimer's disease is reduced by 50% in post-menopausal women taking oestrogen replacement. Limited clinical trials of estrogen treatment in women with this disease have documented beneficial effects on cognitive function. Estrogen supplementation has been shown to preserve cognitive function in nonAlzheimer's cases, too. Effective anti-estrogen treatment might result in some cognitive diminution [possibly concentration and memory functions decreasing somewhat]. 

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