ABSTRACT
Objective To investigate the expression of programmed death ligand 1(PD-L1) in primary tumor cells(TCs) and tumor-infiltrating immune cells(TICs) in patients with liver metastases from colorectal cancer(CRC) and determine its predictive value for recurrence after microwave ablation(MWA) of liver metastases. Methods The paraffin-embedded specimens of 28 patients with CRC liver metastasis were collected retrospectively. The expression of PD-L1 in the primary lesions was detected by immunohistochemistry, and the relationship between PD-L1 and clinical features was analyzed. Recurrence-free survival(RFS) was analyzed by Kaplan-Meier method and Log rank test. Cox proportional hazards regression model was used to analyze the factors influencing recurrence. Results The positive rates of PD-L1 in TCs and TICs in primary CRC were 14.3%(4/28) and 46.4%(13/28), respectively. PD-L1 expression in primary TICs of CRC patients with liver metastases was significantly correlated with the largest hepatic tumor diameter (P < 0.05). PD-L1 expression in primary TICs of CRC patients with liver metastasis was correlated with poor RFS after MWA (P < 0.05). PD-L1 expression in primary TICs and the largest hepatic tumor diameter > 3 cm in CRC patients with liver metastases were the risk factors for recurrence after MWA (P < 0.05). Conclusion PD-L1 expression in primary TICs of CRC patients with liver metastasis may increase the risk of recurrence after MWA for liver metastasis.