Estrogen Receptor

Letrozole is categorized pharmacologically as an Antineoplastic Agent and as an Aromatase Inhibitor. The action of Aromatase Inhibitors is to inhibit the production of estrogens by stopping the conversion of androgen into estrogen.

- Aromatase Inhibitors operate by blocking the aromatase enzyme from converting androgen to estrogen in women who have gone through menopause.
- Post-menopausal women get estrogen from the conversion of androgen into estrogen in the tissues of the body.
- In contrast women who have not gone through menopause receive their estrogen from the ovaries.
- By inhibiting the production of estrogen, the estrogen receptor [ER]-positive and/or progesterone receptor [PR]-positive tumor breast cancer cells cannot grow.