The effects of tamoxifen on the uterus.

The main uterine effect of prolonged tamoxifen use is an increased incidence of proliferative abnormalities of the endometrium. These form an overlapping pathological spectrum ranging from simple hyperplasia to invasive malignancy, with hyperplastic endometrial polyps and polyp-cancers occupying the intermediate ground. The factors involved in the genesis of these lesions remain poorly understood but a combination of inherited factors and cumulative tamoxifen dosage may be important.