PD-L1 expression in pleural effusions of pulmonary adenocarcinoma and survival prediction: a controlled study by pleural biopsy.

PD-L1 expression in pleural effusions (PE) of lung adenocarcinoma (ADC) was compared with pleural biopsies and the positive expression in PE was correlated with survival time. The matched slices from same patient's pleura and PE were collected which both were pathologically verified positive. Immunohistochemistry (IHC) was used to detect PD-L1 expression. A total of 51 eligible cases were enrolled, including 30 males and 21 females. The average age was (67.06 ± 12.10) years. PD-L1 expression wasn't statistically significant in pleura and cell masses (P > 0.05) and the correlation was statistically significant (r = 0.585, P = 0.000). Using an IHC scores of 5 point as a cutoff, positive PD-L1 expression in the pleura was 11.63% and that in the cell masses was 23.26%, and difference was significant (P < 0.05). The correlation coefficient was 0.605. Among 35 cases underwent systemic anti-tumor treatment, the mean survival time with positive PD-L1 expression in PE was 17.370 ± 1.827 months, which was significantly shorter than that with the negative (29.944 ± 2.671 months) (χ2 = 4.507, P = 0.034). Positive PD-L1 expression in PE is higher than in the pleura and their correlation is well. It may predict the short survival time after systemic anti-tumor treatment.