A

Evidence: A prospective study comparing 70 premenopausal women found significantly higher staining scores for both vascular endothelial growth factor (VEGF) and transforming growth factor-β1 (TGF-β1) in endometrial polyps than in adjacent normal endometrium, in both proliferative and secretory phases. The authors concluded that “there was increased expression of TGF-β1 and VEGF in polyps compared to adjacent normal endometrial tissue,” implicating these cytokines in polyp formation [Peng et al., 2011, PMID 21726930].