The Correlation Between ¹⁸F-FDG PET/CT Metabolic Parameters And PD-L1 Expression And Clinicopathological Features Of NSCLC

Part 1 PD-L1 expression correlation with metabolic parameters of 18F-FDG PET/CT and clinicopathological characteristics in pulmonary adenocarcinoma and squamous cell carcinomaObjective Immunotherapy targeting at blocking programmed cell death-1(PD-1)/programmed cell death-ligand 1(PD-L1)pathway has shown promising results in non-small cell lung cancer(NSCLC)patients.Exploring PD-L1 expression of tumor cells could help to select NSCLC candidates for immunotherapy.18F-FDG PET/CT could provide phenotypic information of malignant tumors.Therefore,this study focused on two common pathological types of NSCLC(adenocarcinoma and squamous cell carcinoma)to explore the relationship between the expression of PD-L1 and 18F-FDG PET/CT metabolic parameters and clinical pathological characteristics,and to analyze its role in predicting the expression of PD-L1.Methods Data of 374 non-small cell lung cancer patients who underwent 18F-FDG PET/CT from January 2017 to August 2018 were retrospectively analyzed.18F-FDG PET/CT metabolic parameters including maximum standard uptake(SUVmax),metabolic tumor volume and total lesion glycolysis of primary lesion(MTV-P,TLG-P),and combination of primary lesion and metastases(MTV-C,TLG-C),age,gender,smoking history,tumor marker,tumor location,size,TNM stage,gene mutation.The expression of PD-L1 was compared with the above indexes by univariate analysis.Multivariate logistic regression was used to analyze the ability of each factor to predict the positive expression of PD-L1,and the best cut-off value for predicting the positive expression of PD-L1 was determined by receiver operating characteristic(ROC)curve analysis.A P value<0.05 was considered statistically significant.Results Among 374 patients,283 were adenocarcinomas and 91 were squamous cell carcinomas.There were 104 cases of PD-L1 positive and 270 cases of PD-L1 negative.PD-L1 expression was positive in 27.8%(104/374)cases.For all 374 NSCLC patients,the mean SUVmax,TLG-P and TLG-C of PD-L1 positive patients were significantly higher than those of PD-L1 negative patients(P<0.05).In addition,the positive expression of PD-L1 was significantly correlated with male,smoking and central lung cancer(P<0.05),but not with other clinicopathological features.When according to the analysis of lung adenocarcinoma and squamous cell carcinoma,only the average SUVmax of the two pathological subtypes was significantly different between PD-L1 positive and negative patients(P<0.05).Multivariate analysis showed that SUVmax was an independent predictor of PD-L1 expression in NSCLC,including adenocarcinoma and squamous cell carcinoma.Conclusion PD-L1 expression of NSCLC was related with SUVmax,TLG,man,smoking,and central location.However,only SUVmax was an independent predictor of PD-L1 positivity,which could help to select NSCLC candidates for immunotherapy.Part 2 Correlation of 18F-FDG PET/CT metabolic parameters with PD-L1 expression and clinicopathological features and prognosis in Pulmonary Sarcomatoid CarcinomaObjective Pulmonary Sarcomatoid Carcinoma(PSC)is a rare non-small cell lung cancer,which doesn't have systematic treatment and has a poor prognosis.The second part of this study aimed to analyze the relationship between 18F-FDG PET/CT metabolic parameters with PD-L1 expression and clinicopathological features of PSC patients,and analyze the prognostic factors,so as to increase the knowledge of pulmonary sarcomatoid carcinoma,a rare non-small cell subtype,and provide theoretical support for prognosis improving.Methods Preoperative 18F-FDG PET/CT findings and parameters of maximum standard uptake value(SUVmax),metabolic tumor volume(MTV),and total lesion glycolysis(TLG)of primary lesion(MTV-P,TLG-P),and combination of primary lesion and metastases(MTV-C,TLG-C)were retrospectively analyzed in 24 patients with PSC confirmed by postoperative pathology.Tumor location,size,TNM stage,serum tumor markers,histopathological features,and mutations were also reviewed.Furthermore,progression-free survival(PFS)of 24 patients was analyzed.The parameters of PET/CT were compared with the above clinicopathological factors by independent sample t-test and one-way ANOVA.Kaplan-Meier survival analysis was used to analyze the progression free survival rate(PFS)of 24 patients.Cox proportional hazards regression was used to analyze the predictive ability of each factor to survival outcome.A P value<0.05 was considered statistically significant.Rusults All 24 enrolled patients(20 men;4 women;age:62 ± 9 years)had single PSC,including 8 spindle cell carcinomas and 16 pleomorphic carcinomas.Six patients had central PSC,and 18 had peripheral PSC(diameter:41±16 mm).Eighteen lesions were located in the upper lobes of bilateral lungs,and 22 showed necrosis.Five cases were at TNM stage ?,12 at stage ?,and 7 at stage ?.The primary tumors were FDG-avid in the 24 cases,with SUVmax of 17.2±10.6.There was no correlation between SUVmax of 18F-FDG PET/CT and tumor location,size,TNM stage.In addition,there was no significant differences in PET/CT metabolic parameters between the two pathological subtypes.The expression of PD-L1 was positive in 21 patients(87.5%).SUVmax of 17 lesions with PD-L1 expression degree?50%was obviously higher than that<50%(P<0.05).Kirsten rat sarcoma viral oncogene homolog(KRAS)gene mutation was found in 6 cases,and their SUVmax was significantly higher than that without KRAS mutation(P<0.05).The median progression free survival of 24 patients was 14 months.The 12-month and 24-month progression free survival rates were 55.9%and 27.8%,respectively.TLG-P and KRAS mutations in primary tumors were significantly correlated with PFS(P<0.05).Conclusions PSC tended to present with intense 18F-FDG accumulation on PET/CT,and SUVmax was useful for assessing PD-L1 and KRAS expression of PSC.TLG-P and KRAS mutation were independent prognostic factors of PSC.