Materials and Methods: This retrospective observational immunohistochemical study was conducted at a tertiary care center between February 2021 and August 2022. Ninety-seven paraffin-embedded endometrial tissue specimens, including proliferative endometrium (n=23), endometrial hyperplasia without atypia (n=16), endometrial hyperplasia with atypia (n=13), Grade 1 endometrioid endometrial carcinoma (n=20), Grade 2 endometrioid endometrial carcinoma (n=14), and Grade 3 endometrioid endometrial carcinoma (n=11), were evaluated immunohistochemically for ERα, NRP1, and E-cadherin expression.

Results: ERα expression was significantly higher in endometrial hyperplasia without atypia compared with Grade 2/3 endometrioid endometrial carcinoma (P < 0.05). NRP1 expression was lower in atypical hyperplasia than in proliferative endometrium (P < 0.05), whereas significantly stronger NRP1 staining was observed in Grade 1 and Grade 2/3 endometrioid endometrial carcinoma compared with proliferative endometrium and hyperplastic lesions (P < 0.05 for all comparisons). E-cadherin expression was significantly decreased in Grade 2/3 endometrioid endometrial carcinoma compared with proliferative endometrium, atypical hyperplasia, and Grade 1 carcinoma (P < 0.05 for all comparisons).

Conclusions: Increased NRP1 expression together with reduced ERα and E-cadherin expression in higher-grade endometrial carcinomas suggests that these markers may be associated with endometrial carcinogenesis and tumor progression. Further studies are needed to clarify the underlying molecular mechanisms.