Tamoxifen, angiogenesis, oestrogens and animal models

Angiogenesis is the remodelling of existing vasculature either by formation of new blood vessels or regression of superfluous vessels. In normal adults there is relatively little angiogenesis, but it is well documented that neovascularisation is required for tumour growth beyond a critical size. The (ER) antagonist TAM is currently the first line therapy for treatment of hormone sensitive breast cancer. However, besides its anti-oestrogenic effects, TAM has also been shown to have anti-angiogenic properties. Although there has been much work on the former, the anti-angiogenic actions of TAM are not well understood.