(Tuesday, 7/31/2018) 3:45 PM - 4:15 PM
Room: Exhibit Hall | Forum 9
Purpose: Radiation pneumonitis (RP) is a dose-limiting toxicity for patients undergoing chemoradiotherapy for non-small cell lung cancer (NSCLC). The occurrence of RP is associated with the irradiated volume of the total lungs receiving a certain dose. The purpose of this study is to investigate whether some parameters from the dose-volume histogram would add predictive power in foreseeing RP.Material and
Methods: 113 patients undergoing radiation therapy were included for this study. The gross tumor volume was delineated using CT grayscale or PET/CT images. Dose-volume histograms (DVH) were analyzed and the relative volumes of total lungs receiving dose ≥ 5 Gy (V5) and ≥ 20 Gy (V20), were evaluated and correlated with RP. The presence of RP was noted during regular follow up and recorded. ROC analysis was performed using SPSS. If both parameters (V5 and V20) were correlated RP, the synergistic effect between V5 and V20 was analyzed.
Results: V5, V20, and mean lung dose (MLD) were all correlated to the development of RP. The mean lung dose was 18 Gy, and the mean of V5 and V20 was 59% and 27%, respectively. V5 and V20 had the strongest correlation (p = 0.037 and 0.028). ROC analysis showed that the area under curve (AUC) was 0.632 for V5 and 0.639 for V20, respectively. When both parameters were combined, a new term (V5*V20) showed that the predictive power was improved with AUC=0.643 and p=0.024, suggesting a synergistic effect between these two parameters.
Conclusion: Studies have shown that the DVH parameters V20 and V30 were significantly correlated with RP, and recent studies also showed the correlation between V5 and RP. Our finding of a synergistic effect between V5 and V20 adds a significant predictor for RP, although the synergistic effect needs to be confirmed on a larger number of patients.
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