Multi-factor Analysis Of Acute Radiation Pneumonia Caused By Radiotherapy For Lung Cancer

[Background]At present,lung cancer has become one of the most common malignant tumors in the world,and its morbidity and mortality rank first in malignant tumors.At different stages of the course of primary lung cancer,about 64% of patients require radiation therapy,and 46% of patients require radiation therapy during the first course of treatment.Radiation lung injury is the most common complication of chest radiotherapy,including early acute radiation pneumonia and late radiation pulmonary fibrosis.The two stages are dynamic and continuous development processes,and there is no clear boundary between the two.According to reports,the incidence of radiation pneumonitis is about 16.7% to 50.3%,and the incidence of ≥2 grade radiation pneumonitis is 10% to 20%,which seriously affects the implementation of radiotherapy of chest tumors and limits the improvement of curative effect.At present,there is no clinical specific treatment method.Therefore,the prevention of radiation pneumonitis is particularly important and is a very challenging task.[Purpose]To explore the role of clinical factors and dosimetric factors in predicting ≥2grade radiation pneumonitis caused by radiation therapy of lung cancer,to further improve the impact of the ratio of the volume of the primary focus to the volume of the lung lobe on radiation pneumonitis,to refine the clinically effective prediction of factors related to the occurrence of ≥2 grade radiation pneumonitis,to provide a basis for better guidance of lung cancer radiotherapy,reduce the occurrence of ≥2 grade radiation pneumonitis,and improve the safety of radiotherapy.[Methods]A total of 192 patients with lung cancer who were diagnosed by pathology and were treated with radiotherapy from January 2015 to July 2018 were collected at a radiotherapy dose of 40 Gy ~ 70 Gy.Collect the general clinical characteristics,dosimetric factors,and radiographic imaging data of patients after radiotherapy,and statistically analyze the relationship between clinical factors,dosimetric factors,and grade 2 radiation pneumonitis.Statistical methods used independent sample t test,chi-square test,non-parametric rank sum test,binary logistic regression analysis,etc.[Result]The incidence of ≥2 grade radiation pneumonitis in the whole group was 22.40%(43/192),of which grade 2 radiation pneumonitis was 14.58%(28/192),grade 3radiation pneumonia was 5.73%(11/192),and grade 4 radiation pneumonia was1.08%(4/193).Univariate analysis showed that the occurrence of ≥2 grade radiation pneumonitis was not related to clinical factors such as gender,age,KPS score,history of smoking,history of COPD,pathological type,clinical stage,combined radiochemotherapy(simultaneous radiochemotherapy or sequential radiochemotherapy),surgical history,respiratory gating technology,and radiotherapy method;there was significantly correlated with whole lung V5 ~ V35,whole lung MLD,primary focus lung lobe V5 ~ V35,primary focus lung lobe MLD(P <0.05);there was no correlation with GTV,lung volume,affected lung DVH parameters,healthy lung DVH parameters,whole lung V40~V65,primary lung lobe V40 ~ V65.Factors with statistical significance(P <0.05)from univariate analysis were included in the multivariate analysis to show that the whole lung V20 was an independent risk factor for radiation pneumonia of grade ≥2.The threshold for calculating the whole lung V20 by ROC curve is: 25.9%.[Conclusion]The occurrence and development of radiation pneumonia is caused by a combination of multiple factors.When formulating a radiotherapy plan,the DVH parameters of the whole lung(V5,V20,V30,MLD)and the DVH parameters of the primary lung lobe(V5,V20,V30,MLD)should be considered.Influencing factors;whole lung V20 is an independent risk factor for the occurrence of ≥2 grade radiation pneumonitis,and it is recommended to limit it to ≤25.9%.