| Background and purposeLung cancer is one of the most common malignancies worldwide.Non-small cell lung cancer(NSCLC)is the most common histological subtype of lung cancer.The immunotherapy in programmed death receptor 1(PD-1)or programmed death ligand 1(PD-L1)shows a good effect in NSCLC patients.Exploring PD-L1 expression can help select candidate immunotherapies for NSCLC.18-fluorodeoxyglucose-positron emission tomography computerized tomography,(18F-FDG PET/CT)is a molecular imaging technique that can provide phenotypic information for malignant tumors.Therefore,this study investigated the correlation between 18F-FDG PET/CT metabolic parameters and PD-L1 expression and clinicopathological features in NSCLC tissues.Meterials and MethodsRetrospective analysis was performed on 111 NSCLC patients who received prior 18F-FDG PET/CT examination in the First Afiliated Hospital of Zhengzhou University from April 2017 to May 2019.Clinical data of enrolled patients included:gender,age,smoking history,surgical history,tumor size,tumor location,TNM stage(according to the International Association for the Study of Lung Cancer Eighth Edition TNM Staging System),carcinogene status(EGFR,ALK),Ki-67,carcinoembryonic antigen,cytokeratin 19 fragment antigen,PD-L1 expression,SUVmax in 18F-FDG PET/CT,neutrophil to lymphocyte ratio(NLR)and platelets to lymphocyte ratio(PLR).SPSS22.0 software was used for statistical analysis of the data.The differences between groups were tested by 2 test,and Fisher’s exact probability method was used when the expected frequency was less than 5.Wilcoxon rank sum test was used for grade data.Spearman method was used to analyze the correlation between SUVmax and PD-L1 expression in NSCLC.The optimal cut-off value of SUVmax for predicting NSCLC PD-L1 expression was obtained by receiver operating characteristic curve,and the sensitivity and specificity were calculated.Multivariate Logistic regression analysis was used to evaluate the correlation between PD-L1 expression and clinicopathological features of NSCLC.Univariate survival analysis was performed by Kaplan-Meier method and Log-rank test.Multivariate survival analysis was performed by Cox risk ratio model.All tests were bilateral,and P<0.05 was considered statistically significant.Results1.The SUVmax value of PD-L1 positive patients was significantly higher than that of PD-L1 negative patients(16.36±6.27>11.62±6.240,P<0.05).ROC showed that the area under the curve was 0.703(95%CI:0.599～0.806,P=0.002),and the optimal cut-off value for SUVmax to predict PD-L1 expression in NSCLC tissues was 11.8,with a sensitivity of 84%and a specificity of 55.8%.Spearman analysis showed that SUVmax value was positively correlated with PD-L1 index(r=0.293,P<0.01).2.Univariate analysis showed that,the proportion of PD-L1 positive patients was significantly higher in male than female patients(76.0%vs.24.0%,P=0.021),significantly higher in smokers than non-smokers(68.0%vs.32.0%;p=0.036),significantly higher in those with lymph node metastases than those without lymph node metastases(84.0%vs.16.0%;P=0.037),significantly higher in those with ki67(%)>30 than those with ki-67(%)<30(72.0%vs.28.0%;P=0.025),and significantly higher in those with SUVmax≥11.8(84.0%)than those with SUVmax<11.8(84.0%vs.16.0%;P<0.001).Multivariate Logistic regression analysis showed that high SUVmax was significantly correlated with positive PD-L1(OR=6.648,95%CI:2.071～21.337,P<0.05).There was no significant correlation between sex,smoking history,lymph node metastasis,Ki-67(%)and PD-L1 expression(all P>0.05).3.The proportion of high value of SUVmax in male was higher than that in female(66.1%vs.33.9%)P=0.021);the proportion of high value of SUVmax in smokers was higher than that in non-smokers(61.0%vs.39.0%,P=0.010);the proportion of high value of SUVmax in patients with tumor size≥31.0mm was higher than that in patients with tumor size<31.0mm(67.8%vs.32.2%,P<0.001);the proportion of high value of SUVmax in advanced patients was higher than that in early patients(83.0%vs.17.0%,P<0.001).In addition,the proportion of high value of SUVmax in patients with NLR≥2.37 was higher than that in patients with NLR<2.37(61.0%vs.39.0%,P=0.049);the proportion of high value of SUVmax in patients with PLR≥141.01 was higher than that in patients with PLR<141.01(66.1%vs.33.9%,P=0.034).4.Univariate Kaplan-Meier analysis showed that positive PD-L1,high SUVmax,tumor≥31.0mm,NLR≥2.37 and PLR≥141.01 were possible adverse prognostic factors affecting progression-free survival(PFS)of patients(P<0.001,P=0.006,P=0.031,P=0.030,P=0.022).Multivariate Cox regression analysis showed that only PD-L1 expression was an independent influencing factor for PFS in NSCLC patients(HR=11.690,95%CI:6.445-21.202,P<0.05).Conclusion1.The metabolic parameter SUVmax of 18F-FDG PET/CT has the ability to predict the expression of PD-L1 in NSCLC.2.High SUVmax was significantly correlated with positive PD-L1.3.The proportion of high SUVmax value was higher in male,smokers,advanced patients,patients with tumor≥31.0mm,NLR≥2.37 and PLR≥141.01.4.PD-L1 expression is an independent influencing factor of PFS in NSCLC patients. |
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