Raloxifene

Raloxifene is a SERM that acts as an anti-estrogen in the breasts, and as estrogen more strongly in bone tissue.

It is increasingly being chosen over tamoxifen because it helps prevent osteoporosis with use of GnRH blockers, and also because it has less or no risk of increasing chances of getting uterine cancer in the general population. It acts as an antagonist in uterine tissue.

It can also be used to treat gynecomastia, and has been shown effective in reducing breast size in those with the condition.

It has been shown to reduce ERα and PR expression in breast tissue in premenopausal women. Additionally, it was shown to decrease the presence of Ki-67, a biomarker for cell proliferation, in breast tissue of premenopausal women.

Note that (as of 2018) Raloxifene can be quite expensive (~US$5 per pill), so it may not be a practical option unless covered by insurance.