| Purpose: This research is to investigate the regular pattern variation of tumor after treating it with Intensity-Modulated Radiation therapy,analyze factors which influence the change of tumor volume after radiotherapy and the prognosis of patients and investigate the correlation between tumor volume and survival in order to improve the prognosis and provide reference for individualized treatment plan.Methods and Materials: Patients with non-small cell lung cancer treated with IMRT between August 2009 and September 2015 in author's hospital were enrolled in this study.Patients' chest CT images before radiotherapy and within l year's reexamination after the radiotherapy are collected and Raystation treatment planning system is used to measure primary tumor volume respectively.Then the relative volume of the tumor and shrinking rate after the radiotherapy respectively are calculated.Paired t-test is utilized to analyze the differences of gross tumor volume between every 2 adjacent months and find the relative tumor volume changing pattern,then the prognosis of patients is analyzed.Possible factors which influence the tumor shrinking rate after radiotherapy by Chi-square test are analyzed.multivariate analysis by logistic regression is performed to study possible influencing factors which influence the tumor shrinking rate.Kaplan-Meier analysis was used to calculate survival.Log-rank analysis was used to compare survival differences between different groups.The prognosis was analyzed by Cox multivariate model.Results: A total of 103 NSCLC patients treated with IMRT were enrolled in this study.The differences of relative volume are compared with paired t-test which are as follows: pre-radiotherapy vs post-radiotherapy(p < 0.001),post-radiotherapy vs post-radiotherapy of 1st month(p <0.01),post-radiotherapy of 10 th month vs post-radiotherapy of 12 th month(p<0.001),but the differences between other adjacent 2 months have not statistical significance.Univariate analysis demonstrates the original tumor volume and BED are the influencing factor which influence the tumor relative volume changes after the radiotherapy(the original tumor volume,? 2= 14.726,P<0.001,BED:? 2= 10.76,P=0.001),but other factors such as gender,age,pathological type are not of statistically significant.Logistic regression analysis demonstrates that the original tumor volume is independent prognostic factors of tumor relative volume changes after the radiotherapy(p <0.001).According to original tumor volume,stratification analysis demonstrates that the differences of two groups: At(1)the small tumor volume group(volume<56cm3 group),there are differences not only between pre-radiotherapy and post-radiotherapy(p < 0.001),post-radiotherapy and post-radiotherapy of 1st month(p was 0.012),but also between post-radiotherapy of 10 th month and post-radiotherapy of 12 th month(p was 0.01),but the differences between other adjacent 2 months have no statistical significance.(2)At the large tumor volume group(volume?56cm3 group),there are differences not only between pre-radiotherapy and post-radiotherapy(p < 0.01),post-radiotherapy and post-radiotherapy of 1st month(p<0.01),but also between post-radiotherapy of 6th month and post-radiotherapy of 8th month(p= 0.01),post-radiotherapy of 10 th month and post-radiotherapy of 12 th month(p<0.05),but the differences between other adjacent 2 months have no statistical significance.The median survival time was 21.6 months and the 1-year?2-year OS rate were 65.6%?41.43% respectively.Univariate analysis shows that group of ECOG score was 1 to 2(p<0.001),no pulmonary disease(p=0.035),TNM stage at I-II(p<0.001),tumor size volume than 56 cm3(p<0.012)were better than the other one.Multivariate analysis gender,ECOG score,tumor size,primary focal areas,received chemotherapy tumor size volume were independent prognostic factors for overall survival in non-small cell lung cancer patients that received IMRT(p<0.05).Conclusions: The tumor volume of NSCLC presents a certain pattern in 1 years after radiotherapy.At the end of radiotherapy,the volume retraction was the most obvious,and at the 1st months after radiotherapy it will continues to shrink and reach the minimum volume.At 2nd to 10 th months after radiotherapy,the tumor volume tends to be stable,after that,there wer an increasing trend of the tumor volume.The tumor with volume small than 56cm3 shrinks more obviously than the other one.There are different patterns between groups divided by the tumor volume of 56cm3,the small group has an increasing trend in the first 10 months after radiotherapy,while the large group was in 6 months.male,peripheral lung cancer,primary tumor volume less than 56cm3,combined with chemotherapy,low ECOG score were the better prognosis. |
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