Programmed Death Ligand-1 (PD-L1) Expression in Endometrial Carcinoma: An Immunohistochemical Study and Correlation with Clinicopathological Parameters

Background Endometrial carcinoma (EC) is among the most prevalent gynecological malignancies worldwide, with increasing incidence linked to obesity and aging populations. Programmed death-ligand 1 (PD-L1) plays a crucial role in tumor immune evasion by interacting with PD-1, and its expression has been implicated in the aggressiveness of several cancers. However, limited data exist on PD-L1 expression in EC and its association with clinicopathological parameters in the Indian population. Methods This retrospective and prospective observational study was conducted on 50 histologically confirmed EC cases. Immunohistochemistry (IHC) for PD-L1 was performed using the Ventana SP263 clone, and positivity was defined as membranous staining in ≥ 1% of viable tumor cells (tumor proportion score, TPS). PD-L1 expression was correlated with age, tumor size, histological subtype, myometrial invasion, cervical stromal invasion, lymphovascular invasion, lymph node status, and microsatellite instability (MSI). Statistical associations were tested using the Chi-square and Fisher’s exact test. Results PD-L1 expression was observed in 12 of 50 cases (24%). PD-L1 positivity was significantly associated with advanced FIGO stage III–IV (54.5% vs. 15.4%; OR, 6.60; 95% CI, 1.52–28.75; p = 0.014), deep myometrial invasion ≥ 50% (47.4% vs. 9.7%; OR, 8.40; 95% CI, 1.89–37.38; p = 0.005), and lymphovascular space invasion (55.6% vs. 17.1%; OR, 6.07; 95% CI, 1.29–28.49; p = 0.027). Conclusion PD-L1 expression in EC was detected in nearly one-quarter of cases and was significantly associated with adverse pathological features such as deep myometrial and lymphovascular invasion. These preliminary findings suggest that PD-L1 expression may reflect adverse tumour biology.