What is the difference between tamoxifen and femara (letrozole)?

Different. Tamoxifen is a selective estrogen agonist/antagonist. It binds to estrogen receptors and depends on which organ it's on, it either exerts anti-estrogen or estrogen effects. Femara (letrozole) is an aromatase inhibitor. It inhibits enzymatic conversion of androgens to estrogen thereby lowering estrogen level.
Mechanism of action. The two drugs are similar. However, the way they work (mechanism of action) is different. They are used to treat hormone sensitive cancers and (tamoxifen) high risk patients. If you are premenopausal, because of the different mechanisms of action, you should not take femara (letrozole).

Related Questions

What are the similarities and differences between tamoxifen and femara (letrozole)?

Different action. Tamoxifen blocks the estrogen receptor, while Femara (letrozole) blocks the formation of estrogen. Estrogen levels are not lowered by tamoxifen, but they are lowered by femara (letrozole). Both cause hot flashes, bone loss, depression, memory problems and decreased libido. Tamoxifen increases blood clot and uterine cancer risk and causes vaginal discharge, while Femara (letrozole) causes more joint pain and vaginal dryness. Read more...
Both are effective. These are two drugs with different mechanisms of action. They are part of breast cancer treatment. Tamoxifen blocks hormone receptors found on some breast cancers. Femara (letrozole) blocks the production of hormones from the adrenal glands, essentially acting as hormone receptors inhibitors. Because of the way these drugs work, Femara (letrozole) can't be used in premenopausal women. Read more...

What are some similarities and differences between tamoxefen and femara (letrozole)?

"anti-estrogens" Both tamoxifen and Femara (letrozole) are drugs used to treat patients with estrogen receptor positive breast cancer. Each drug affects breast cancer cells through a slightly different mechanism of action. Tamoxifen can be used for all women whereas Femara (letrozole) is only used after menopause. Read more...
Requires long answer. The answer is too long to fit into 400 characters but there is a nice summary at http://www.Health.Com/health/condition-article/0, 20188924, 00.Html. Read more...