The Analysis Of Non-small Cell Lung Cancer (NSCLC) Long-term Survival With Three-dimensional Conformal Radiotherapy And Its Influence Factors

Objective: A retrospective analysis was carried out to evaluate the lately and long-term effect of NSCLC, and to analyze the relationship of factors which affect the survival of NSCLC.At the same time, the clinical and physical factors were analyzed with radiation pneumonitis and esophagitis,and evaluated these factors for optimal planning to treat NSCLC.Methods: From August 2000 to December 2004,107 NSCLC patients received definitive radiotherapy and eligible for the analysis.In all the patients,48 patients accepted three dimensional conformal radiotherapy(3D-CRT),the other 59 patients accepted conventional radiotherapy (CRT) before 3D-CRT. All of the patients received the biological effective dose (BED) between 50-78Gy.All patients were immobilisated with thermoplast while quiet respiration. When the CT scan was performed,the images were transformed and restructured in three dimension by the 3D-CRT planning system.Then we delineated the gross target volume (GTV)and enlarged 6~8mm in three-dimensional orientation as the clinical target volume (CTV) .The planning target volume (PTV) was an enlarged volume of 5mm around the CTV in three dimensions.CRT scheme was constituted by simulator, given two fields by anterior and posterior with SSD 100 centimeters.The irradiated fields included primary tumor and corresponding mediastinum. The center of irradiated field was designed as the unitary point to calculate dose,then adding dose by 3D-CRT. At last, we fit the irradiated fields of CRT into the second course of 3D-CRT treatment planning system.The related physical parameters were evaluated by dose-volume histogram (DVH).The acute radiation injury (radiation pneumonitis and irradiation esophagitis )was graded according to World Health Organization and RTOG's acute injury grade standard. The significance of related prognostic factors on the survival was evaluated by univariate and multivariate analysis;The correlation of every variable was evaluated by Spearman or Pearson analysis; The rate of radiation pneumonitis,radiation esophagitis and minification of tumor was analyzed byχ2 test ;The multivariate effect on radiation pneumonitis and esophagitis was statisticed by Logistic regression model; The correlative indexes of treatment plan were analyzed by T test.Results: The investigate was finished at the end of 2007,the rate of fellow-up was 95.5 %. In all the patients ,the median survival time was 13 months and the mean survival time was 24 months.The overall survival rate(OS) of 1-year ,2-years and 3-years was 55.14%,34.58% and 21.50% respectively. These clinical and physical parameters,for example , sex, smoking, tumor maximum diameter and tumor volume , N stage, clinical stage, the therapeutical effect,the volume of GTV,CTV,PTV were important prognostic factors by univariate analysis.Cox harzed model showed sex,N stage,tumor volume, the therapeutical effect and GTV volume were likely to be independent prognostic factors.The rate of radiation pneumonitis was 62.5%,and the rate of the≥2 grade radiation pneumonitis was 38.3%, 23 case grade 2,14 case grade 3,4 case grade 4.Univariate analysis showed chronic obstructive pulmonary disease,beam number, lung mean dose, lung V5~V40 were important influence factors for radiation pneumonitis.Father more , lung mean dose, beam number and lung V30 were likely to be the independent factors of radiation pneumonitis by logistic model. Univariate analysis showed the maximum and mean dose of esophagus, the volume of esophagus irradiated, the esophagus V40-V60,the esophagus LETT45-LETT60 existed correlation with radiation esophagitis.The heart mean dose,heart V40~V50, spinal cord maximum dose and mean dose, spinal cord V40,V45 were significantly different between 3D-CRT and CRT followed by 3D-CRT scheme by T test(p<0.05).Conclusion: 1.The sex ,smoking, the maximum diameter of tumor, tumor volume ,N stage, clincal stage, the therapeutical effect can be used to evaluate the NSCLC long-time effect;2. lung mean dose, beam number and lung V30 were the independent influence factors of radiation pneumonitis; 3.Univariate analysis showed the maximum and mean dose of esophagus, the volume of esophagus irradiated, the esophagus V40-V60,the esophagus LETT45-LETT60 existed significantly correlation with radiation esophagitis. 4.Compared the second course 3D-CRT and the whole course 3D-CRT ,the later had better feature,which can protect their surrounding normal tissue and organs(spinal cord and heart).