Loss of B-cell lymphoma 2 immunohistochemical expression in endometrial hyperplasia: A specific marker of precancer and novel indication for treatment: A systematic review and meta-analysis.

B-cell lymphoma 2 loss is a marker of endometrial precancer, with a high specificity and high diagnostic accuracy if the EIN classification is used. Thresholds of Bcl-2 expression not involving a complete loss should not be considered. Bcl-2 loss in endometrial hyperplasia may be a novel indication for treatment when precancerous features are ambiguous in a histological examination. Bcl-2 loss correlates better with EIN classification than with the WHO classification, suggesting that glandular complexity is an important precancerous feature.