The Associated Factors Analysis Of Acute Radiation-induced Pneumonitis In EC Patients And Making Predictions Based On LKB Model

Esophageal carcinoma has the characteristics of low cure rate and high recurrence rate,and radiation therapy is still the main treatment for it so far.Due to the special tumor location and narrow target area,the radiotherapy was carried out from both sides of the chest,so radiotherapy complications especially for RP were frequent.Known as acute radiation induced lung injury,the symptoms of RP usually occur more than two or three weeks after radiotherapy.The main symptoms include:irritating cough or dry cough,accompanied by shortness of breath and chest pain,low heat even high fever on some patients.Even worse,it could develop into radiation-induced pulmonary fibrosis,which can’t be reversed.Accordingly,as a common side effect of radiotherapy,RP has a bad effect on the life quality and patient survival after radiotherapy.Although the current developed medical technology has achieved a certain effect on the treatment of radiation pneumonia,yet the best way to cope with it is still how to prevent it actively and effectively.Through the effective prediction on the RP,the radiation dose could be adjusted in a timely manner,and the radiotherapy plan could be modified in order to improve the radiotherapy accuracy.Through a series of such measures,the incidence of RP is minimized,thus providing a guarantee for the patients’life.All these effects made the prediction of the RP for EC patients imperative.So far,the study on the influencing factors of RP is uncountable.Clinical factors,containing of age,radiation technology and tumor location have been found to be correlated with RP occurrence.The use of IMRT has been suggested to decrease the occurrence of RP compared with 3D-CRT.Also,Gagliardi et al.obtained two distinct dose-response curves by splitting patient groups according to age,showing that correlation between age and the increased risk of RP.The influence of the tumor location was confirmed in a study by Mehta.In earlier studies,smoking was found to decrease the RP risk frequency and to be independent of the effect of dosimetric parameters on RP risk.However,for effecting parameters of RP,some contradictions and opposing conclusions exist in the literature,such as the MLD threshold dose differs in different studies.This implies that the correlation between dosimetric parameters and RP needs to be further clarified,particularly in EC.To fit LKB NTCP model of RP in Chinese population with EC,and investigate the association between dosimetric,clinical factors and RP,71 sets of patient data were retrospectively investigated.Utilizing dose volume histogram（DVH）information,the parameters of the NTCP model(m,n and TD₅₀)were derived through the maximum likelihood estimation method.Then,the chi-squared test and the univariate analysis were used to investigate the correlation between clinical factors（including age,sex etc.）,dosimetric parameters and RP.Finally,the multivariate analysis was used to research the correlation between RP and factors whose significance value P<0.05 in the former analysis.The fitted parameters for RP finally came out to be:m=0.27,n=0.11,TD₅₀=41.78.In the chi-square test and univariate analysis,the smoking status,V₂₀,MLD and TD were found to be correlated with RP（p<0.05）.In multivariate analysis,no parameters was proved to correlate well with the risk of RP in contrast to other factors.A LKB model of RP for the Chinese population with EC was established firstly.The effect of some clinical and dosimetric parameters on RP occurrence was confirmed.