Expression Of Soluble Programmed Death 1 Ligand-1 In Plasma Of Patients With Lung Cancer And Its Correlation With Prognosis

Objective:The aim of the study was to evaluate the expression of soluble programmed death 1ligand-1(s PD-L1) in the plasma of patients with lung cancer and its correlation with clinic-pathological features as well as survival outcomes.Methods:A total of 159 patients with lung cancer who were diagnosed by histopathology or cytopathology in Shanxi Tumor Hospital between July 2013 to October 2015 were enrolled. Blood samples plasma were collected at the time of diagnosis. 85 samples of healthy subjects matching in sex and age from the Health care Center of the hospital were also studied as control. The level of soluble PD-L1 protein in the blood was measured using anenzyme-linked immunosorbent assay(ELISA) kit. 64 cases of lung cancer patients who were treated with platinum based chemotherapy for 4-6 cycles were followed up. The associations between the level of s PD-L1 expression and clinicopathologic features and prognosis were statistically analyzed.Results:The mean s PD-L1 of the peripheral blood plasma in lung cancer patients and healthy controls were 4.298±3.211ng/ml and 1.851±0.712ng/ml, respectively. Expression of s PD-L1 in lung cancer patients was significantly up-regulated compared with health people( P<0.001). A cut-off value of 2.37ng/ml was distinguished in patients according to Receiver operating characteristic curve(ROC). Chi-square test was utilized to analyze the relationship between s PD-L1 expression and clinicopathologic features.The expression of s PD-L1 was associated with abdominal organ metastasis(P=0.015).Survival curves were plotted by using the Kaplan-Meier method. A high s PD-L1 expression had a worse prognosis than a low expression in patients(P=0.001).Conclusion:Our results indicated that the elevated expression of s PD-L1 may play a pivotal role in tumor immune evasion. The s PD-L1 in plasma may serve as a molecular prognosis marker for patients with lung cancer.