ABSTRACT
The concept of agents like tamoxifen, which were previously described as anti-oestrogens, having differential agonist and antagonist effects between tissues was developed during the early 1990s and the term ‘selective estrogen receptor modulator’ (or SERM) was coined to describe such compounds. During the 1980s, it was already known that the balance of agonist and antagonist effects of tamoxifen and like compounds within a tissue was affected by prevailing levels of oestrogen. Jordan and colleagues showed that tamoxifen could inhibit the growth of mammary tumours but enhance the growth of endometrial tumours in the same animal. Importantly, agonist effects on bone could also be demonstrated in ovariectomized rats with not only tamoxifen but also keoxifene, which later became known as raloxifene.
