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OA24 - Radiotherapy of Lung Cancer: Recent Developments (ID 411)
- Event: WCLC 2016
- Type: Oral Session
- Track: Radiotherapy
- Presentations: 1
OA24.03 - Cardiac Toxicity after Radiation for Stage III NSCLC: Pooled Analysis of Dose-Escalation Trials Delivering 70-90 Gy (ID 4322)
14:20 - 15:50 | Author(s): B.C. Jensen
Radiation (RT) associated cardiac injury in patients with lung cancer is of unclear significance. RTOG 0617 demonstrated reduced overall survival (OS) with dose-escalated RT for Stage III NSCLC, with higher heart doses predicting for worse OS. We assessed the impact of heart doses on toxicity and survival for patients enrolled on several prospective RT dose-escalation trials.
From 1996-2009, 133 patients with Stage III NSCLC (ECOG PS 0-1) were treated on six prospective trials using induction/concurrent chemotherapy and dose-escalated conformal RT to 70-90 Gy. Broad clinical outcomes (e.g. OS) were prospectively assessed. RT plans were reviewed, cardiac structures were defined, and dose/volume metrics were computed. Patient records were retrospectively reviewed for post-RT symptomatic cardiac events (symptomatic pericardial effusion, acute coronary syndrome, and pericarditis). Baseline cardiac risk was calculated using the World Health Organization / International Society of Hypertension (WHO/ISH) score. A competing risks model accounting for the risk of death was used for statistical analysis.
112 patients were included in the final analysis. Median f/u was 19 mo. (75 mo. for the 39 patients without documented progression). Median OS and PFS were 22 and 12 mo. Median prescribed RT dose was 74 Gy. 15 patients (13%) had symptomatic cardiac events (6 pericardial effusion, 5 myocardial infarction, 2 unstable angina, 2 pericarditis) at median 26 mo. post-RT (range, 7-68). On univariate analysis, Heart mean dose (p=0.001), Heart V5Gy (p<0.001), and Heart V30Gy (p=0.002) were associated with symptomatic cardiac events, whereas baseline WHO/ISH score (p=0.204) and coronary artery disease (p=0.109) were not. Heart doses were higher in patients with vs without events (mean 22Gy vs 11Gy, V5Gy 60% vs 35%, V30Gy 35% vs 14%). On multivariate pair analysis accounting for baseline risk, heart doses remained significant predictors of cardiac events (e.g. Heart mean dose, p=0.001, HR 1.05 / 1Gy). 2-year competing risk-adjusted rate of symptomatic cardiac events was 11.1% vs 1.5% for Heart mean dose ≥15Gy vs <15Gy (p=0.003, HR 6.7). 34 patients (30%) had asymptomatic pericardial effusions. There was no association between heart doses and OS.
Clinically significant symptomatic cardiac events following high-dose thoracic RT for Stage III NSCLC occurred in 13% of patients at a median 2 years post-RT, with the rate appearing to be heart dose dependent. RT-associated cardiac toxicity in the definitive treatment of Stage III NSCLC may occur earlier than historically understood, and heart doses should be minimized. Supported in part by NIH grant CA69579.
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