Correlation of PD-L1 Expression With Microsatellite Instability and p53 Status in Endometrial Cancer: A...

This study aimed to evaluate the correlations between programmed death-ligand 1 (PD-L1) expression, the mismatch repair system, and p53 status in endometrial cancer, considering tumor stage.

A retrospective analysis of clinicopathological and immunohistochemical data was conducted on 254 patients treated at Holy Cross Cancer Centre (Poland). The majority of patients had endometrioid adenocarcinoma (89.8%) and FIGO stage I disease (69.7%).

Positive PD-L1 expression (threshold ≥ 1%) was observed in only 3.9% of cases, while mismatch repair system deficiency and aberrant p53 expression were present in 18.1% and 17.3%, respectively. No significant correlations were found between PD-L1 expression and clinicopathological parameters, repair system status, or p53 (p = 0.328 and p = 0.359, respectively). However, a significant association (p = 0.046) was noted between PD-L1 positivity and the microsatellite-unstable/hypermutated molecular subtype, with 30% of PD-L1 positive tumors exhibiting this subtype compared to 10.2% of PD-L1 negative tumors.

No molecular marker demonstrated a significant association with recurrence risk (p > 0.05), in contrast to the FIGO stage, which showed a significant correlation (p < 0.001). Although PD-L1 expression was rare, it was significantly associated with microsatellite instability, highlighting the potential of molecular classification to identify candidates for immunotherapy. However, the low frequency of PD-L1 positivity and the small sample size warrant caution in interpreting these findings, and further research is needed to confirm the clinical relevance of PD-L1 in endometrial cancer.