LAUSR

INTRODUCTION Proliferative endometrium has been reported in 15% of endometrial biopsies of women 50 and older. In contrary to endometrial hyperplasia, proliferative endometrium has not been associated with risk of endometrial cancer. We sought to report on the long-term outcome of postmenopausal women diagnosed with proliferative endometrium. METHODS Retrospective cohort study of 1808 women 55 and older who underwent endometrial sampling between 1/1997-12/2008. Outcome data was available through 2/2018. Women with proliferative endometrium were compared to those with atrophic endometrium for future development of endometrial hyperplasia or cancer. A sub-analysis was performed for those who presented with postmenopausal bleeding. Uni and multivariable logistic regression analysis were used to assess for confounders. RESULTS PE was diagnosed in 297 (16.4%) cases. 962 met inclusion criteria, 278 with proliferative endometrium and 684 with atrophic endometrium. Women with proliferative endometrium were younger (61.2 vs. 64.5,p<.0001) and had a higher BMI (33.9 vs. 30.6kg/m2,p<.0001). More African American women had proliferative endometrium Both groups had a similar length of surveillance (11.9 vs. 11.5year,p=0.27). Women with proliferative endometrium developed more endometrial hyperplasia or cancer (11.9% vs. 2.9%,p<.0001), any endometrial cancer (5.8% vs 1.8%,p=0.002), atypical endometrial hyperplasia (2.2% vs. 0.4%,p=0.02) and non-atypical endometrial hyperplasia (2.0 vs. 0.7%,p=0.001). The risk for endometrial cancer and endometrial hyperplasia remained similar after excluding cases on hormonal therapy (12.2% vs. 3%,p=0.001). On logistic regression analysis proliferative endometrium histology (OR=3.89. 95%CI=2.03-7.49,p<.0001), age >60 (OR=1.98, 95%CI=1.03-3.82,p=0.04) and BMI>35 (OR=2.3, 95%CI=1.09-4.83,p < 0.0001) remained significant risk factors for progression to cancer. CONCLUSION One in six postmenopausal women who underwent endometrial sampling had proliferative endometrium. 11.9% of them developed endometrial cancer or hyperplasia, a four-fold greater incidence than women with atrophic endometrium. The findings of this study suggest that long-term monitoring is warranted for women with postmenopausal bleeding and a proliferative endometrium histology. Further studies are needed to examine if a treatment is required to negate the risk of unopposed estrogen.