Anastrozole (in men)

The verdict

Our read at a glance.

Whether suppressing oestrogen in men produces a benefit worth the skeletal and lipid cost.

The signal

The pharmacology is reliable: anastrozole lowers oestradiol and raises luteinising hormone and testosterone in men, and it has been studied in older men with low testosterone, in adolescent gynaecomastia, and in male infertility with an elevated oestradiol-to-testosterone ratio. Registered trials in men exist across those settings. What the literature has not established is that the resulting hormonal picture translates into better outcomes for the things men take it for. Its approved identity remains adjuvant treatment of hormone-receptor-positive breast cancer in postmenopausal women, which is where its outcome evidence lives.

The unknown

The right target. Oestradiol in men is not a waste product: it is required for bone mineralisation, lipid handling, endothelial function and libido, and there is no established therapeutic range for men being managed this way.

Our read

A drug that reliably changes a number on a lab report, used by people who assume that number is the goal. Oestrogen is not the enemy in male physiology, and the most common outcome of aggressive aromatase inhibition is a man with worse joints, worse lipids and worse sexual function than before.