A 54-year-old woman is on tamoxifen for the prevention of breast cancer on the basis of her strong family history, nulliparity, and early age at menarche. Her gen. physical and gynaecological examination is within normal limits. Which of the following is this patient most likely to develop while on tamoxifen?

Tamoxifen is SERM (Selective estrogen receptor modulator) Tamoxifen is an antagonist of the estrogen receptor in breast tissue its active metabolite, hydroxy-tamoxifen. In other tissues such as the endometrium, it behaves as an agonist, Its paial agonist on the endometrium and has been linked to endometrial cancer and hence many patients are advised GnRH agonist therapy to suppress the Pituitary and hence the endometrium is also 'resting'.