Endometrial carcinoma and tamoxifen: clearing up a controversy.

During the past 5 years, a number of case reports and clinical trial results have associated tamoxifen therapy with an increased incidence of endometrial carcinoma. A review of the literature shows that there are over 200 cases of endometrial carcinoma reported in tamoxifen-treated women. Most cases are Stage I (82%), grade 1-2 disease (80%), which is consistent with the Surveillance Epidemiology and End Results Reporting data of 74 and 79% for Stage I and grade 1-2 endometrial carcinoma. We conclude that there is a modest increase in endometrial carcinoma incidence during tamoxifen therapy (i.e., 2/1000 tamoxifen treated women per year versus 1/1000 women per year for Surveillance Epidemiology and End Results Reporting), that there is no strong association with duration of therapy, and that tamoxifen is not associated with a high-grade, poor prognosis disease. The benefits of tamoxifen in lives saved exceeds the incidence of endometrial carcinoma.