Expanded HILUS Trial: A Pooled Analysis of Risk Factors for Toxicity From Stereotactic Body Radiation Therapy of Central and Ultracentral Lung Tumors.

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 bronchopulmonary 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. Similar dose constraints should be applied to the intermediate bronchus as to the mainstem bronchi.

The HILUS-Trial-a Prospective Nordic Multicenter Phase 2 Study of Ultracentral Lung Tumors Treated With Stereotactic Body Radiotherapy.

INTRODUCTION: Stereotactic body radiation therapy of thoracic tumors close to the central airways implies risk of severe toxicity. We report a prospective multicenter phase 2 trial for tumors located less than or equal to 1 cm from the proximal bronchial tree with primary end point of local control and secondary end point of toxicity. METHODS: Stereotactic body radiation therapy with 7 Gy × 8 was prescribed to the 67% isodose encompassing the planning target volume. The patients were stratified to group A (tumors ≤ 1 cm from the main bronchi and trachea) or group B (all other tumors). Risk factors for treatment-related death were tested in univariate analysis, and a logistic regression model was developed for fatal bronchopulmonary bleeding versus dose to the main bronchi and trachea. RESULTS: A total of 65 patients (group A/group B, n = 39/26) were evaluated. The median distance between the tumor and the proximal bronchial tree was 0 mm (0-10 mm). The 2-year local control was 83%. Grade 3 to 5 toxicity was noted in 22 patients, including 10 cases of treatment-related death (bronchopulmonary hemorrhage, n = 8; pneumonitis, n = 1; fistula, n = 1). Dose to the combined structure main bronchi and trachea and tumor distance to the main bronchi were important risk factors. Dose modeling revealed minimum dose to the "hottest" 0.2 cc to the structure main bronchi and trachea as the strongest predictor for lethal bronchopulmonary hemorrhage. CONCLUSIONS: On the basis of the presented data, 7 Gy × 8, prescribed to the planning target volume-encompassing isodose, should not be used for tumors located within 1 cm from the main bronchi and trachea. Group B-type tumors may be considered for the treatment on the basis of an individual risk-benefit assessment and a maximum dose to the main bronchi and trachea in the order of 70 to 80 Gy (equivalent dose in 2 Gy fractions).

The quality assurance process for the ARTSCAN head and neck study - a practical interactive approach for QA in 3DCRT and IMRT.

AIM: This paper describes the quality assurance (QA) work performed in the Swedish multicenter ARTSCAN (Accelerated RadioTherapy of Squamous cell CArcinomas in the head and Neck) trial to guarantee high quality in a multicenter study which involved modern radiotherapy such as 3DCRT or IMRT. MATERIALS AND METHODS: The study was closed in June 2006 with 750 randomised patients. Radiation therapy-related data for every patient were sent by each participating centre to the QA office where all trial data were reviewed, analysed and stored. In case of any deviation from the protocol, an interactive process was started between the QA office and the local responsible clinician and/or physicist to increase the compliance to the protocol for future randomised patients. Meetings and workshops were held on a regular basis for discussions on various trial-related issues and for the QA office to report on updated results. RESULTS AND DISCUSSION: This review covers the 734 patients out of a total of 750 who had entered the study. Deviations early in the study were corrected so that the overall compliance to the protocol was very high. There were only negligible variations in doses and dose distributions to target volumes for each specific site and stage. The quality of the treatments was high. Furthermore, an extensive database of treatment parameters was accumulated for future dose-volume vs. endpoint evaluations. CONCLUSIONS: This comprehensive QA programme increased the probability to draw firm conclusions from our study and may serve as a concept for QA work in future radiotherapy trials where comparatively small effects are searched for in a heterogeneous tumour population.