Letrozole

Status

FDA-approved. FDA-approved labeling exists as Femara for adjuvant and extended adjuvant treatment of hormone receptor-positive early breast cancer in postmenopausal women, and for advanced disease. No approved indication in men. The label documents decreases in bone mineral density, increases in cholesterol and fatigue.

What it is

A potent oral aromatase inhibitor used in oncology and fertility settings.

What published research measured

A non-steroidal aromatase inhibitor, more potent at suppressing oestrogen than anastrozole, with a substantial randomized trial base in breast cancer including the BIG 1-98 and MA.17 trials. It is also widely used, with good trial support, for ovulation induction — a randomized trial published in the New England Journal of Medicine found letrozole produced higher live birth rates than clomiphene in women with polycystic ovary syndrome. Off-label use in men is not supported by outcome data. Because it suppresses oestradiol more completely than the alternatives, the bone density and lipid consequences of over-suppression arrive faster, and profoundly low oestradiol in men is itself associated with joint pain, low libido and adverse effects on bone.

Source

BIG 1-98 and MA.17 trials · Legro et al. 2014, New England Journal of Medicine — letrozole versus clomiphene in polycystic ovary syndrome · FDA labeling for Femara

Sources

• Half-life source for Letrozole