Impact of Incidental Cardiac Radiation on Cardiopulmonary Toxicity and Survival for Locally Advanced Non-Small Cell Lung Cancer: Reanalysis of NRG Oncology/RTOG 0617 With Centrally Contoured Cardiac Structures International Journal of Radiation Oncology, Biology, Physics ORAL SCIENTIFIC SESSION| VOLUME 96, ISSUE 2, SUPPLEMENT , S129-S130, OCTOBER 01, 2016
Date
10/01/2016Abstract
Purpose/Objective(s)
RTOG 0617 showed high dose RT had a greater risk of death than standard dose. Higher heart dose was associated with worse overall survival (OS) on multivariate analysis. However, the variability in submitted heart contours and no contouring of substructures limited the ability to accurately quantify the role of heart dose and ultimately set meaningful dose constraints.
Materials/Methods
Five thoracic radiation oncologists collectively contoured the cardiac structures for each available case, guided by a common atlas. Anatomic structures defined were pericardium (P), ventricles (V), atria (A), and coronary space (CS). Volumes of each structure and overlap with PTV, distribution of V5, V10, V20, V30, V40, V45, V60, maximum dose (Dmax), and mean dose (MD) were analyzed. Volumes and doses were compared between centrally contoured P and submitted heart contours. Impact of volume and dose to each structure and combined structures on OS, local failure (LF), distant failure (DF), progression free survival (PFS), and treatment related pulmonary, esophageal, cardiovascular and esophageal toxicity were evaluated using Cox PH model and logistic regression model with multiplicity adjustments.
Results
Among 495 analyzable cases, 57 (11.5%) were not available for re-contouring and excluded. Re-contoured P volumes, PTV overlap with P, and dose volumes were larger than submitted heart contours. On univariate analysis all analyzed dose volumes and MD to P were associated with increased risk of death, P < 0.001. Similar relationships were found with V5-60 and MD to A and V and Dmax to the V, P < 0.01. On multivariate analysis, larger PTV volume and Gr3+ esophagitis remained associated with worse OS (P < 0.05); in addition, MD to P (HR = 1.019, P = .007) and V45 for A (HR = 1.007, P = 0.022), V (HR = 1.015, P = 0.0043), and CS (HR = 1.005, P = 0.0022) each had a detrimental impact on OS. On Univariate analysis MD to P and V5-45 were associated with all Gr3+ pulmonary toxicity (P < 0.05) and MD and V30-60 with Gr3+ pneumonitis (<0.05). On multivariate analysis MD to P (OR = 1.044, P = 0.0372) and stage IIIB disease (OR = 2.51, P = 0.0342) were associated with Grd3+ pneumonitis.
Conclusion
Excessive RT doses to cardiac structures including pericardium MD, V45 to Atria, ventricles, and CS have a detrimental effect on overall survival. Pericardium MD was associated with severe treatment related pneumonitis.
Author List
E.M. Gore C. Hu V. Bar Ad C.G. Robinson M.D. Wheatley J.A. Bogart Y. Garces V.S. Kavadi S. Narayan P. Iyengar J.S. Witt J.W. Welsh C.D. Koprowski J.M. Larner J.D. BradleyAuthor
Elizabeth M. Gore MD Professor in the Radiation Oncology department at Medical College of WisconsinView Online
