Tumor-stroma Ratio Predicts Prognosis and PD-L1 Expression in Hepatocellular Carcinoma

Background: With the in-depth research on the tumor microenvironment, the tumor stroma is considered to play a leading role in malignant tumor behavior, and PD-L1 is also related to the tumor stroma. The tumor-stroma ratio (TSR) has been regarded as a novel prognostic factor in many cancers. Our study aims to assess the TSR and PD-L1 clinical value in hepatocellular carcinoma (HCC) patients.

Methods: Ninety-five patients who were diagnosed with HCC were included in our study. TSR was estimated on HCC specimen hematoxylin-eosin staining (HE) sections, and the optimal TSR cut-off value was determined by receiver operating characteristic (ROC) curves. The correlation between the TSR and clinicopathologic features was also calculated. Immunohistochemistry (IHC) staining was also carried out to analyze the PD-L1 expression level in HCCs.

Results: The optimal TSR cut-off value was 0.525. The median OS of the stroma-high and stroma-low groups was 27 and 36 months, respectively. The median RFS of the stroma-high and stroma-low groups was 14.5 and 27 months, respectively. In the Cox multivariate analysis, the TSR was an independent prognostic factor for HCC overall survival (OS) and recurrence-free survival (RFS) in patients who underwent liver resection. IHC staining revealed TSR-high HCC samples with high PD-L1-positive cell expression.

Conclusions: Our results suggest that the TSR can predict the prognosis of HCC patients who underwent liver resection. The TSR is related to PD-L1 expression and may be a therapeutic target that can dramatically improve HCC patients' clinical outcomes.