Letrozole (CGS 20267), exemestane [
E0941] and anastrozole [
A2370] are third generation, and potent and selective aromatase inhibitors. In postmenopausal women, estrogens are mainly derived from the action of the aromatase which is responsible enzyme for the aromatization of androgens ([
A0845] and [
T0027]) into estrogens ([
E0026] and [
E0025]) respectively in the periphery. The growth of the breast cancer is stimulated or maintained by estrogens. Letrozole, exemestane and anastrozole inhibit aromatase and estrogen synthesis, resulting in suppressing tumor growth. (The product is for research purpose only.)