Tamoxifen/Uterine CA. Studies have linked the use of tamoxifen to an increased risk - perhaps twice the natural rate - to endometrial cancer. While the drug blocks estrogen receptors in the breast to assist in limiting the spread and growth of breats cancer, it apparently can augment the estrogen effects on the uterus and contribute to uterine cancer development.
It can. The most definitive study that looked at uterine cancer rates associated with tamoxifen found that women had twice the risk of developing uterine cancer, at a rate of 1 per 500 women per year. This rate is far lower than the rate of breast cancer prevention; thus, the benefits far outweigh the risks. A better alternative after menopause is aromatase inhibitors, which do not increase this risk.