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

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

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。

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 Vs 〈 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.