Background: In the 2014 WHO classification of endometrial hyperplasia (EH), complex EH is lumped together with simple EH in the benign category of non-atypical EH.
Objective: To assess the risk of coexistent cancer in complex EH and simple EH without atypia, through a systematic review and meta-analysis.
Methods: Electronic databases were searched from their inception to January 2019 for relevant articles.
Results: Twelve studies assessing a total of 804 non-atypical EH were included. The risk of coexistent cancer was significantly higher in complex EH (12.4%) than in simple EH (2%), with an OR of 6.03 (p = 0.0002).
Conclusion: Even in the absence of cytologic atypia, complex EH is associated with a significant risk of coexistent cancer. Further studies are necessary to investigate the need for a revision in the WHO classification.
Keywords: Coexistent cancer; Complex hyperplasia; Endometrial hyperplasia; Endometrial intraepithelial neoplasia.