非小细胞肺癌全肺切除术后胸部放疗致肺损伤的剂量学分析

目的:确定全肺切除术后胸部放疗引起放射性肺炎的预测参数,并设立参考阈值。方法:2007年4月-2010年10月前瞻性、连续纳入44例全肺切除术后的非小细胞肺癌患者。所有患者术后均接受胸部放疗(三维适形放疗或调强放疗)。记录肺平均剂量(mean lung dose,MLD)以及接受5Gy及以上剂量照射的肺体积占总肺体积的百分比V5以及V10、V15、V20和V30。应用受试者工作特征曲线评估这些参数与放射性肺炎之间的关系,找出预测能力较强的参数并确定安全阈值。结果:所有44例患者中,发生2级以上放射性肺炎的有13例(29.5%),其中发生3级的4例,无患者发生4和5级放射性肺炎。所有的放射性肺炎均发生在放疗后9个月内,其中84.6%(11/13)的放射性肺炎发生在放疗后6个月内,中位时间为放疗后2个月。受试者工作特征(receiver operating characteristic,ROC)曲线下面积最大的3个参数分别为V5(0.824)、MLD(0.806)和V10(0.801),参考阈值分别为21.5%、450cGy和8.5%。4例发生3级放射性肺炎的患者,MLD>800(804～887)cGy,V5>28%(28%～42%),V10>20%(20%～36%)。结论:全肺切除术后行胸部放射治疗是安全而可行的,为避免发生2级以上的放射性肺炎,建议余肺剂量限定于V5<21.5%(敏感度为78.6%、特异度为84.6%),MLD<450cGy(敏感度为79.6%、特异度为65.4%),V10<8.5%(敏感度为85.7%、特异度为61.5%)。为避免发生3级以上的放射性肺炎,建议余肺MLD<800cGy。

Dose-volume histogram analysis on radiation-induced pneumonitis after pneumonectomy for non-small cell lung cancer

Objective:To identify the predictive parameters and threshold values for thoracic radiation-induced pneumonitis after complete pneumonectomy for NSCLC(non-small cell lung cancer).Methods:Forty-four consecutive patients with NSCLC were enrolled prospectively in this study between April 2007 and October 2010.All patients underwent thoracic radiotherapy(three-dimension conformal radiotherapy or intensity-modulated radiotherapy) after pneumonectomy.Lung dosimetric parameters such as MLD(mean lung dose) and percentage of lung volume receiving 5 Gy or more(V5),V10,V15,V20 and V30 were recorded.The relevance of these parameters and radiation-induced pneumonitis was assessed by ROC(receiver operating characteristic) curve to pick up the more predictive parameters and also to set up the threshold limit values.Results:Of the 44 patients,13 patients(29.5%) developed grade 2 or greater radiation-induced pneumonitis;among the 13 patients,4 developed grade 3 radiation-induced pneumonitis.No patients developed grade 4 or 5 pneumonitis.The median time from the end of radiotherapy to the onset of pneumonitis was 2 months.All the cases of pneumonitis were diagnosed within 9 months,and 84.6%(11/13) were confirmed within 6 months after radiotherapy.Three parameters with the largest area under the ROC curve were V5(0.824),MLD(0.806) and V10(0.801).The threshold values of the 3 parameters were calculated to be 21.5%,450 cGy and 8.5%,respectively.As for the 4 patients with grade 3 pneumonitis,the MLD>800 cGy(804-887cGy),V5 > 30%(28%-42%) and V10>20%(20%-36%).Conclusion:It is safe and feasible to give radiation therapy to thorax after pneumonectomy.To avoid pneumonitis of grade 2 or more,it is recommended that the dose to the contralateral lung should be constrained as V5 < 21.5%(sensitivity 78.6%,specificity 84.6%),MLD < 450 cGy(sensitivity 79.6%,specificity 65.4%) and V10 < 8.5%(sensitivity 85.7%,specificity 61.5%).To avoid severe pneumonitis of grade 3 or more,the MLD of the contralateral lung should be limited below 800 cGy.