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

ABSTRACT

Objective: To identify the predictive parameters and threshold values for thoracic radiationinduced 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, V 20 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. © 2012 by Tumor.