Effect Of V5 On Radiation - Induced Lung Injury

Part1Analysis Of V5Predicting Radiation Pneumonitis In Patients Received Thoracic Irradiation Treatment[Objective]To examine V5as the dosimetric predictor of radiation pneumonitis in patients received thoracic radiation therapy beside V20, V30and MLD.[Methods]One-hundred patients receiving thoracic irradiation from2011to2012at Northern Jiangsu People’s Hospital were retrospectively reviewed, from which esophageal and lung cancer patients were eighty-six and fourteen, respectively. Pneumonitis was graded by using the Common Terminology Criteria for Adverse Events version4.0. Patient clinical data included age, gender, ECOG performance status, history of chemotherapy, survivance, CT images before and after therapy and radiation therapy plan. Dosimetric parameters (V5, V10, V15, V20, V25, V30) were entered as continuous variables. A cross tabulation, an independent t-test and a receiver observer curve (ROC) were used to analyze the data.[Results]In the final,50(50%) of total100patients had grade0-1RP,44(44%) had grade2RP,4(4%) had grade3RP and2(2%) had grade4RP. No significant discrepancy was found between grade0-1and grade2-4in the following clinical parameters, such as age, gender, ECOG performance status and history of chemotherapy. The ROC indicated the AUC value was0.627for V5(P=0.034). When V5<50%vs. V5≥50%, the incidence of grade≥2RP was33.3%and59.36%(P <0.05),50%was a threshold.[Conclusion]In this study, after thoracic irradiation by using conventional technique IMRT, grade0-1RP developed in50%, grade2in44%, grade3in4%and grade4in2%of all patients. When MLD, V20,V30and other potential related parameters were controlled in safe range, V5was proved to be significantly associated with RP, and the ROC curve indicated the AUC value was0.627(P=0.034). By further data analyzing, we recommend V5should be kept as low as possible, in addition to the conventional dosimetric factors, when V5<50%vs. V5≥50%, the incidence of grade≥2RP was33.3%and59.36%(P<0.05),50%was a threshold. Part2Experiment Research of Correlation Between V5And Radiation-induced Lung Injury[Objective]To establish the rabbit model of radiation-induced lung injury for the study of its relationship with V5by measuring TNF-α and TGF-β1content.[Methods]Thirty New Zealand rabbits were randomly divided into six groups, every eight in V540%,50%,60%,70%,80%and control group. Each rabbit received CT scan, delineation of target region and went on radiation with DT30Gy/3F by three-yield IMRT. All rabbits were sacrificed at8week after irradiation. The pathological changes were observed with light microscopies and the expression of TNF-α and TGF-β1in local lung tissue were detected by immunohistochemistry. ANOVA and S-N-K test were used for statistic analysis.[Results]The expression of TNF-α and TGF-β1enhanced in each experimental group than control group. High expression were detected in higher V5percentage group. The expression of TGF-β1:V540%showed significantly different with70%,80%, respectively(P<0.05). But no differences were found by comparing with V550%,60%and control group. All but V540%group was statistically different with control group (P<0.05). The expression of TNF-α:Only V570%and control group was statistically different related to V580%(P<0.05).[Conclusion]When V5was set by40%, it could reduced the occurrence of radiation-induced lung injury. And the threshold of predicting radiation-induced lung injury could be near50%.