(Sunday, 7/12/2020) [Eastern Time (GMT-4)]
Room: AAPM ePoster Library
Purpose:
To apply Voxel-Based Analysis (VBA) for investigating the thoracic dose-patterns associated with pericardial effusion (PCE) and mortality in lung cancer patients.
Methods:
We analyzed 178 patients treated with proton or IMRT to prescribed doses of 66 or 74 Gy (2 Gy/fraction) with concurrent chemotherapy (CHT). We considered four endpoints: PCE of CTCAE grade=2 and mortality at 12 and 24 months from irradiation, with patients censored for follow-up.
VBA of local dose differences between patients classified according to each endpoint was performed according to [Palma IJROBP 2019]. Clusters with dose differences correlated with outcomes at p<0.05 (S(0.05)) were generated, and associated mean doses (MD) extracted. Impact of clinical variables and of PCE on Overall Survival (OS) was analyzed by Cox regression with time-dependent covariates.
Results:
One- and 2-year PCE occurrence were 32% (45/139) and 47% (42/90). The multivariable analysis (MVA) showed a significant correlation between adjuvant CHT with 1-year PCE (p=0.05), and between age and 2-year PCE (p=0.004).
One- and 2-year mortality were 28% (49/176) and 48% (79/166). MVA selected pre-treatment cardiac disease (p=0.04), age (p=0.03), GTV size (p=0.001) and weight (p=0.02) for 1-year mortality, and age (p=0.05) and GTV size (p=0.37) for 2-year mortality.
On Cox analysis, only GTV size (p<0.001) and age (p=0.028) were correlated with OS.
VBA identified two largely overlapping clusters S(0.05) for 1- (410 cc, MD(PCE)=[42±30] Gy, MD(noPCE)=[25±22] Gy) and 2-years (390 cc, MD(PCE)=[42±37] Gy, MD(noPCE)=[21±23] Gy) PCE in the heart and lungs. The VBA did not highlight significant dose-patterns related to mortality endpoints.
Conclusion:
VBA highlighted dose-patterns associated with PCE in both heart and lungs, opening new perspectives on the analysis of multi-organ contribution to thoracic toxicities. Tumor volume and older age were the only significant factors for OS, which seems not associated with PCE or dose to heart or pulmonary healthy tissues.
Keywords
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Taxonomy
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