| Research background and purpose:Radiation pneumonitis(RP)is a common acute side effect after thoracic radiotherapy.The current limited dose or safe dose of bilateral lungs is mainly obtained from the3D-CRT,the characteristic of dose distribution in IMRT are different from 3D-CRT,and the limits is different due to the change of radiotherapy technique.The main purpose of this study is to analyze the lung cancer patients who received IMRT/VMAT and to explore the influencing factors related to the occurrence of RP,so as to provide a reference basis for reducing the risk of RP.Materials and Methods:A total of 288 patients with lung cancer who received IMRT at the Sichuan Cancer Hospital from January 2017 to May 2019 were collected and followed up for more than6 months.The clinical data of the patients were analyzed,including age,gender,PG-SGA,smoking,lung disease,pulmonary function and tumor status.Inflammatory markers including NLR,LMR,SII,CRP,LDH were assessed at 4 time points:before RT,during RT(30Gy),at the end of RT,1 month after RT.Collect GTV volume,PTV volume,dosimetric parameters(including MLD and lung volume receiving ≥xGy),etc.Evaluate RP according to RTOG standard.The SPSS 25.0 software was used for analysis and processing,and Lasso regression model was used to analyze the collected data for the prediction significance of ≥ 2 RP.The predictive value of high risk factors was analyzed using the ROC.P <0.05 was considered statistically significant.Result:1.71 patients(24.7%)developed ≥ 2 grade RP,in which the incidence of grade 2RP was 60.6%,the incidence of grade 3 RP was 29.6%,the incidence of grade 4 RP was4.2%,and the incidence of death was 5.6%.RP usually occurs within 3 months after RT.The incidence of RP during RT is 15.5%.The incidence of RP within 3 months after RT is 73.2%.After 3 months,the incidence of RP is 11.3%.2.Univariate analysis showed that the clinical factors included age(P=0.046),PG-SGA score(P<0.001),pathological type(P=0.025),lung disease(P<0.001),FEV1(P=0.028),tumor size(P<0.001),tumor location(P=0.019),Chemotherapy(P=0.002)and surgery(P=0.010)are all related factors of ≥ 2 RP.3.Univariate analysis of inflammation indicators showed that compared with non-RP group,NLR(during radiotherapy,at the end of radiotherapy,1 month after radiotherapy),SII,CRP,LDH(before radiotherapy,during radiotherapy,at the end of radiotherapy,1 month after radiotherapy),were significantly increased in RP group,while LMR decreased significantly during radiotherapy and at the end of radiotherapy.The difference was statistically significant(P < 0.05).4.Univariate analysis of radiophysical parameters,compared with the non-RP group,the total dose of radiotherapy,the ipsilateral lung(MLD,V10,V13,V15,V20,V30),the contralateral lung(MLD,V5),total lungs(MLD,V5,V13,V15,V20,V30),GTV volume,PTV volume,GTV / LVipsi,GTV / LV,PTV / LVipsi,PTV / LV,were increased in RP group,the difference was statistically significant(P < 0.05).5.Lasoo multivariate regression analysis showed that PG-SGA score,tumor size,NLR level at the end of radiotherapy,V30 ipsi,V30 and PTV/LV were independent risk factors for grade 2 RP.The area under the ROC curve of PG-SGA score is the largest,AUC=0.711(95% CI,0.637 ~ 0.786,P<0.001).From the ROC curve,the optimal critical values of NLR level,V30 ipsi,V30 and PTV/LV at the end of radiotherapy were5.57(P=0.001),21.5%(P<0.001),10.5%(P<0.001)and 5.4%(P<0.001),respectively.6.Gender,smoking history,clinical stage,diabetes,Chemoradiotherapy,total cycle of chemotherapy,the ipsilateral lung(V5,VS5),the Contralateral lung(VS5,V10,V13,V15,V20,V30),lung VS5 and total lung volume were not correlated with RP(P>0.05).Conclusion:1.Male,≥ 60 years old,PG-SGA score of B 、 C,Sqcc,with underlying lung disease,FEV1 < 1.92 L,tumor diameter ≥ 5cm,tumor located in the middle and lower lobe and chemotherapy with TP regimen were the clinical risk factors of ≥grade 2 RP.2.Patients with increased NLR,SII,LDH,CRP and decreased LMR during radiotherapy are more likely to develop into RP.3.Total radiation dose ≥ 60 Gy,DVH parameters(MLD,V5,V10,V13,V15,V20,V30),GTV volume,PTV volume,GTV/LVipsi,GTV/LV,PTV/LVipsi and PTV/LV were physical dose risk factors for ≥grade 2 RP.4.PG-SGA score,,tumor size,NLR at the end of RT,V30 ipsi,V30 and PTV/LVwere independent risk factors for ≥ grade 2 RP.Among them,the comprehensive predictive value of PG-SGA score is greater,and the best critical values of NLR level at the end of radiotherapy,V30 ipsi,V30 and PTV/LV are 5.57,21.5%,10.5% and 5.4%,respectively. |
