Refining Critical Structure Contouring in STereotactic Arrhythmia Radioablation (STAR): Benchmark Results and Consensus Guidelines from the STOPSTORM.eu Consortium.

BACKGROUND AND PURPOSE In patients with recurrent ventricular tachycardia (VT), STereotactic Arrhythmia Radioablation (STAR) shows promising results. The STOPSTORM consortium was established to investigate and harmonise STAR treatment in Europe. The primary goals of this benchmark study were to standardise contouring of organs at risk (OAR) for STAR, including detailed substructures of the heart, and accredit each participating centre. MATERIALS AND METHODS Centres within the STOPSTORM consortium were asked to delineate 31 OAR in three STAR cases. Delineation was reviewed by the consortium expert panel and after a dedicated workshop feedback and accreditation was provided to all participants. Further quantitative analysis was performed by calculating DICE similarity coefficients (DSC), median distance to agreement (MDA), and 95th percentile distance to agreement (HD95). RESULTS Twenty centres participated in this study. Based on DSC, MDA and HD95, the delineations of well-known OAR in radiotherapy were similar, such as lungs (median DSC=0.96, median MDA=0.1mm and median HD95=1.1mm) and aorta (median DSC=0.90, median MDA=0.1mm and median HD95=1.5mm). Some centres did not include the gastro-oesophageal junction, leading to differences in stomach and oesophagus delineations. For cardiac substructures, such as chambers (median DSC=0.83, median MDA=0.2mm and median HD95=0.5mm), valves (median DSC=0.16, median MDA=4.6mm and median HD95=16.0mm), coronary arteries (median DSC=0.4, median MDA=0.7mm and median HD95=8.3mm) and the sinoatrial and atrioventricular nodes (median DSC=0.29, median MDA=4.4mm and median HD95=11.4mm), deviations between centres occurred more frequently. After the dedicated workshop all centres were accredited and contouring consensus guidelines for STAR were established. CONCLUSION This STOPSTORM multi-centre critical structure contouring benchmark study showed high agreement for standard radiotherapy OAR. However, for cardiac substructures larger disagreement in contouring occurred, which may have significant impact on STAR treatment planning and dosimetry evaluation. To standardize OAR contouring, consensus guidelines for critical structure contouring in STAR were established

Heart and Lung Dose as Predictors of Overall Survival in Patients With Locally Advanced Lung Cancer. A National Multicenter Study

INTRODUCTION: It is an ongoing debate how much lung and heart irradiation impact overall survival (OS) after definitive radiotherapy for lung cancer. This study uses a large national cohort of patients with locally advanced NSCLC to investigate the association between OS and irradiation of lung and heart.METHODS: Treatment plans were acquired from six Danish radiotherapy centers, and patient characteristics were obtained from national registries. A hybrid segmentation tool automatically delineated the heart and substructures. Dose-volume histograms for all structures were extracted and analyzed using principal component analyses (PCAs). Parameter selection for a multivariable Cox model for OS prediction was performed using cross-validation based on bootstrapping.RESULTS: The population consisted of 644 patients with a median survival of 26 months (95% confidence interval [CI]: 24-29). The cross-validation selected two PCA variables to be included in the multivariable model. PCA1 represented irradiation of the heart and affected OS negatively (hazard ratio, 1.14; 95% CI: 1.04-1.26). PCA2 characterized the left-right balance (right atrium and left ventricle) irradiation, showing better survival for tumors near the right side (hazard ratio, 0.92; 95% CI: 0.84-1.00). Besides the two PCA variables, the multivariable model included age, sex, body-mass index, performance status, tumor dose, and tumor volume.CONCLUSIONS: Besides the classic noncardiac risk factors, lung and heart doses had a negative impact on survival, while it is suggested that the left side of the heart is a more radiation dose-sensitive region. The data indicate that overall heart irradiation should be reduced to improve the OS if possible.</p

Expanded HILUS trial : a pooled analysis of risk factors for toxicity from stereotactic body radiation therapy of central and ultracentral lung tumors

Abstract: Purpose: Stereotactic body radiation therapy for tumors near the central airways implies high-grade toxic effects, as concluded from the HILUS trial. However, the small sample size and relatively few events limited the statistical power of the study. We therefore pooled data from the prospective HILUS trial with retrospective data from patients in the Nordic countries treated outside the prospective study to evaluate toxicity and risk factors for high-grade toxic effects. Methods and Materials: All patients were treated with 56 Gy in 8 fractions. Tumors within 2 cm of the trachea, the mainstem bronchi, the intermediate bronchus, or the lobar bronchi were included. The primary endpoint was toxicity, and the secondary endpoints were local control and overall survival. Clinical and dosimetric risk factors were analyzed for treatment-related fatal toxicity in univariable and multivariable Cox regression analyses.Results: Of 230 patients evaluated, grade 5 toxicity developed in 30 patients (13%), of whom 20 patients had fatal bronchopul-monary bleeding. The multivariable analysis revealed tumor compression of the tracheobronchial tree and maximum dose to the mainstem or intermediate bronchus as significant risk factors for grade 5 bleeding and grade 5 toxicity. The 3-year local control and overall survival rates were 84% (95% CI, 80%-90%) and 40% (95% CI, 34%-47%), respectively.Conclusions: Tumor compression of the tracheobronchial tree and high maximum dose to the mainstem or intermediate bronchus increase the risk of fatal toxicity after stereotactic body radiation therapy in 8 fractions for central lung tumors. Simi-lar dose constraints should be applied to the intermediate bronchus as to the mainstem bronchi.(c) 2023 Elsevier Inc. All rights reserved

Heterogeneous FDG-guided dose-escalation for locally advanced NSCLC (the NARLAL2 trial): Design and early dosimetric results of a randomized, multi-centre phase-III study

Background and purpose: Local recurrence is frequent in locally advanced NSCLC and is primarily located in FDG-avid parts of tumour and lymph nodes. Aiming at improving local control without increasing toxicity, we designed a multi-centre phase-III trial delivering inhomogeneous dose-escalation driven by FDG-avid volumes, while respecting normal tissue constraints and requiring no increase in mean lung dose. Dose-escalation driven by FDG-avid volumes, delivering mean doses of 95 Gy (tumour) and 74 Gy (lymph nodes), was pursued and compared to standard 66 Gy/33 F plans. Material and methods: Dose plans for the first thirty patients enroled were analysed. Standard and escalated plans were created for all patients, blinded to randomization, and compared for each patient in terms of the ability to escalate while protecting normal tissue. Results: The median dose-escalation in FDG-avid areas was 93.9 Gy (tumour) and 73.0 Gy (lymph nodes). Escalation drove the GTV and CTV to mean doses for the tumour of 87.5 Gy (GTV-T) and 81.3 Gy (CTV-T) in median. No significant differences in mean dose to lung and heart between standard and escalated were found, but small volumes of e.g. the bronchi received doses between 66 and 74 Gy due to escalation. Conclusions: FDG-driven inhomogeneous dose-escalation achieves large increment in tumour and lymph node dose, while delivering similar doses to normal tissue as homogenous standard plans