What is the mechanism of action of Tamoxifen?

Tamoxifen functions as a Selective Estrogen Receptor Modulator (SERM), which means it has the unique ability to bind to estrogen receptors and exert varying effects depending on the target tissue. In breast tissue, Tamoxifen competitively inhibits the binding of estrogen to its receptor, thereby blocking estrogen's proliferative effects on breast cancer cells. This is particularly beneficial in the treatment and prevention of hormone receptor-positive breast cancer.

In contrast, its mechanism is distinct from that of aromatase inhibitors, which prevent the conversion of androgens to estrogens, or from CDK4/6 inhibitors and mTOR inhibitors that target cell cycle regulation and signaling pathways involved in cancer proliferation. By selectively modulating estrogen receptor activity, Tamoxifen provides a targeted approach to managing certain types of breast cancer, highlighting its significance in oncological therapies.