Quantitative Assessment of p53 Immunohistochemical Expression Is Associated with Adverse Clinicopathologic Features in p53 Wild-Type Endometrioid Endometrial Carcinoma

Objective: Endometrioid endometrial carcinoma (EEC) generally has a favorable prognosis, yet some cases exhibit aggressive behavior unexplained by standard parameters. Although p53 immunohistochemistry (IHC) primarily serves as a surrogate for TP53 mutations, quantitative variation within the wild-type (wt) category may hold prognostic value. This study investigated whether the proportion of p53-positive tumor cells correlates with established prognostic parameters in p53-wt EEC.Methods: Eighty-eight p53-wt EEC hysterectomy specimens (2022–2024) were retrospectively analyzed. Two pathologists independently evaluated p53 nuclear positivity percentages. Clinicopathological data, including grade, tumor size, myometrial invasion, cervical involvement, lymphovascular invasion (LVI), and microsatellite instability (MSI) status, were analyzed. An optimal cutoff for p53 expression was determined via Receiver Operating Characteristic (ROC) analysis.Results: p53 positivity ranged from 1% to 90%. ROC analysis identified a 4% cutoff, stratifying cases into low (≤4%, n=36) and high (>4%, n=52) expression groups. High p53 expression was significantly associated with LVI (p=0.0049), higher tumor grade (p