Clinical Significance Of Serum Inflammatory Factors In Non-imaging Diagnosis Of Radiation Pneumonia

Objective: To investigate the correlation between the changes of serum biomarkers interleukin-6(IL-6),C-reactive protein(CRP),procalcitonin(PCT)and radiation pneumonia(RP)in patients with thoracic malignant tumors during radiotherapy.Methods: In this study,96 patients with malignant thoracic tumors treated by radiotherapy in Zhongda Hospital Affiliated to Southeast University from March 2015 to December 2017 were selected as subjects.The clinical and pathological parameters,dosimetric parameters,serum IL-6,CRP and PCT concentrations at 0 Gy,30~40 Gy,50~60 Gy,1 month after radiotherapy were collected.The incidence of RP was assessed according to Common Terminology Criteria for Adverse Events(CTCAE)version 4.0.The evaluation endpoint of RP was greater than or equal to grade 2.Risk factors of RP occurrence were explored by single factor and multi-factor analysis.Furthermore,the ROC curve was made to judge its diagnostic value for RP.Results: In this study,96 patients with malignant thoracic tumors underwent radiotherapy were enrolled and 28 of them developed RP.The serum levels of IL-6 and CRP in RP group were significantly higher than those in non-RP group at the same time point(p<0.05).However,there was no significant difference in serum PCT concentration between the two groups during the whole course of radiotherapy(p> 0.05).With the progress of radiotherapy,there was no significant trend of increase in serum PCT concentration which was within normal range during the whole process.On the ROC curve made by IL-6,the area under the ROC curve was 0.695.The cut-off point was 15.99pg/ml.The corresponding sensitivity and specificity were 57.1% and 79.4% respectively.Similarly,the area under the ROC curve of CRP was 0.752 and the cut-off point was 5.64 mg/L.The corresponding sensitivity and specificity were 84.6% and 65.2% respectively.When IL-6 and CRP were combined to diagnose,the cut-off point of ROC curve was 0.22.The area under ROC curve was 0.785.The corresponding sensitivity and specificity were 75.0% and 73.5% respectively.Conclusion: The serum levels of IL-6 and CRP in RP group were significantly higher than those in non-RP group during the whole radiotherapy,suggesting there was a correlation between cytokines IL-6,CRP and the occurrence of RP.These two indicators were expected to be used as early non-imaging biomarkers for predicting the occurrence of RP and their diagnostic value was better when combined.There was no significant difference in serum PCT concentration between the two groups.PCT was within the normal range during the whole radiotherapy which suggesting that PCT could be used as an index to differentiate RP from bacterial pneumonia.