Aromasin, a new drug to treat post-menopausal advanced breast cancer in patients for whom treatment with tamofixen was ineffective, has been shown to inhibit the production of estrogen, upon which some breast cancer cells depend. Furthermore, studies indicate that Aromasin, which reduces the risk of tumor progression by 18 percent and the risk of death by 23 percent, is more beneficial than the hormone therapy, megestrol acetate.
In post-menopausal women, the principle source of estrogen comes from the conversion of adrenal and ovarian androgens to estrogens by the aromatase (exemestane) enzyme. For post-menopausal women with hormone-dependent breast cancer, Aromasin serves as an aromatase inhibitor. As a result, the concentrations of estrogen, on which breast cancer cells may depend, are lowered. This estrogen-depriving process nicknamed, "suicide inhibition," is irreversible. However, it does not affect other enzymes involved in the steroidogenic pathway up to a concentration at least 600 times higher than that inhibiting the aromatase enzyme.