Abstract:
To explore the correlation of radiation-induced pneumonitis ( RIP ) and esophagitis (RIE) with dosimetric parameters in patients treated with three-dimensional conformal radiation therapy ( 3DCRT ) for non-small cell lung cancer ( NSCLC ). Methods: From August 2000 to December 2004, data from 104 NSCLC patients treated with definitive 3D-CRT were collected. Logistical regression analyses were performed to test the association between RIP and the influencing factors. The clinical efficiency was analyzed using the receiver-operating characteristic ( ROC ) curve based on the above analysis. Results: In the study group, the rate of RIP was 62.6%, and the rate of ≥grade 2 was 38.3%. Univariate analysis showed that the lung mean dose and lung V5-V40 were important factors influencing RIP. Multivariable analysis indicated that lung V35 was likely to be an independent factor. The optimal cutoff value for lung V35 was 20.75%, corresponding to a sensitivity of 66.10% and specificity of 81.00% in the ROC curve. Both the gross tumor volume ( GTV ) and planning target volume ( PTV ) of NSCLC, as well as esophagus V60 were also found to be independent parameters for predicting RIE. The optimal cutoff value for esophagus V60 was 12.50%, corresponding to a sensitivity of 81.30% and specificity of 69.60% in the ROC curve. There was a significant difference between the areas under the ROC curve of esophagus V60 as well as the GTVs and PTVs of NSCLC ( P < 0.05 ). Conclusion: Lung V35 as well as the GTV and PTV of NSCLC are likely to be independent factors in predicting RIP. Esophagus V60 is likely to be an independent factor in predicting RIE, respectively.