Significant risk of occult cancer in complex non-atypical endometrial hyperplasia

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.