Trends in the incidence of endometrial intraepithelial neoplasia and endometrial cancer by type, age, and socioeconomic status in Denmark 2005–2022

Objective: To investigate temporal incidence trends in endometrial intraepithelial neoplasia and endometrial cancer by histological type, age at diagnosis, and socioeconomic status in Denmark over the period 2005–2022. Main outcome measures: We identified all cases of endometrial intraepithelial neoplasia and endometrial cancer in 2005–2022, and obtained individual-level information on education, income and hysterectomies for the total Danish female population from nationwide registries. Hysterectomy-corrected age-standardized incidence rates were calculated for endometrial intraepithelial neoplasia and endometrial cancer, overall and stratified by type, age, and socioeconomic status. To summarize incidence trends over time, the annual percentage change was calculated. Results: During the study period, 2560 females were diagnosed with endometrial intraepithelial neoplasia and 12,845 with endometrial cancer. The incidence of endometrial intraepithelial neoplasia was stable (range: 3.1–4.3 per 100,000 female-years) independent of age, and was most common among postmenopausal women. The overall incidence of endometrial cancer was also stable, at approximately 15 per 100,000 female-years. Among postmenopausal women, the incidence of endometrioid tumors decreased, whereas non-endometrioid tumors increased; in 2021–2022, non-endometrioid cancers accounted for 20.6% of all cases. Among females with higher socioeconomic status, the incidence of endometrioid endometrial cancer decreased. In contrast, the incidence of endometrial intraepithelial neoplasia and non-endometrioid endometrial cancer increased among females with lower socioeconomic status. Conclusion: The incidence of endometrial intraepithelial neoplasia and endometrial cancer overall remained stable. The incidence of endometrial cancer varied by both subtype and age. Our results suggest increasing rates of endometrial intraepithelial neoplasia and non-endometrioid tumors among females with lower socioeconomic status and a decreasing trend of endometrioid cases among the highest socioeconomic groups.