Benign and hyperplastic endometrial changes associated with tamoxifen use.

For nearly 20 years, tamoxifen has been successfully used in the management of breast cancer. Tamoxifen is a mixed estrogen agonist/antagonist that has a proliferative effect on the endometrium. The drug has been associated with a higher percentage of endometrial polyps and hyperplasia than in control patients as well as slightly increased risk of endometrial cancer. Although patients need to undergo annual gynecologic exams and abnormal vaginal bleeding needs to be aggressively followed up, the utility of routine gynecologic screening of tamoxifen patients has not been established and requires further study. Transvaginal sonography is a useful tool for detecting endometrial proliferation; however, an appropriate cut-off point for further intervention must be established. A cut-off point that is too low for abnormal endometrial thickness would result in a large number of unnecessary endometrial biopsies. Routine office endometrial biopsy needs further study as a screening method for breast cancer patients on tamoxifen.