Long-term outcome of postmenopausal women with proliferative endometrium on endometrial sampling.

Background: Proliferative endometrium has been reported in 15% of endometrial biopsies of women aged 50 years and older. Contrary to endometrial hyperplasia, proliferative endometrium has not been associated with the risk of endometrial cancer.

Objective: This study aimed to report on the long-term outcome of postmenopausal women who received a diagnosis of proliferative endometrium.

Study Design: This is a retrospective cohort study of 1808 women aged 55 years and older who underwent endometrial sampling between January 1997 and December 2008. Outcome data were available through February 2018. Women with a proliferative endometrium were compared with those with an atrophic endometrium for future development of endometrial hyperplasia or cancer. A subanalysis was performed for those who presented with postmenopausal bleeding. Uni- and multivariable logistic regression analyses were used to assess for confounders.

Results: In this study, 297 women (16.4%) received a diagnosis of proliferative endometrium. Furthermore, 962 women met the inclusion criteria. Among those women, 278 had a proliferative endometrium, and 684 had an atrophic endometrium. Women with a proliferative endometrium were younger (61.2 vs 64.5 years; P<.0001) and had a higher body mass index (33.9 vs 30.6 kg/m; P<.0001). More African American women had a proliferative endometrium. Both groups had a similar length of surveillance (11.9 vs 11.5 years; P=.27). Women with a proliferative endometrium had a higher risk of developing endometrial hyperplasia or cancer (11.9% vs 2.9%; P<.0001), any endometrial cancer (5.8% vs 1.8%; P=.002), atypical endometrial hyperplasia (2.2% vs 0.4%; P=.02), and nonatypical endometrial hyperplasia (2.0% vs 0.7%; P=.001). The risk of developing endometrial cancer and endometrial hyperplasia remained similar after excluding cases on hormonal replacement therapy (12.2% vs 3%; P=.001). On logistic regression analysis, proliferative endometrium histology (odds ratio, 3.89; 95% confidence interval, 2.03-7.49; P<.0001), age >60 years (odds ratio, 1.98; 95% confidence interval, 1.03-3.82; P=.04), and body mass index >35 kg/m (odds ratio, 2.3; 95% confidence interval, 1.09-4.83; P<.0001) remained significant risk factors for progression to cancer.

Conclusion: One of the 6 postmenopausal women who underwent endometrial sampling had a proliferative endometrium. Furthermore, 11.9% of women developed endometrial hyperplasia or cancer, a 4-fold greater incidence than women with an 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.