Inter-observer variability in target delineation increases during adaptive treatment of head-and-neck and lung cancer

Authors

  • Rudi Apolle OncoRay – National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden - Rossendorf, Dresden, Germany;  Helmholtz-Zentrum Dresden - Rossendorf, Institute of Radiooncology – OncoRay, Dresden, Germany
  • Steffen Appold OncoRay – National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden - Rossendorf, Dresden, Germany;  Department of Radiotherapy and Radiation Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
  • Henk P. Bijl Department of Radiation Oncology, University Medical Center Groningen, Groningen, The Netherlands
  • Pierre Blanchard Department of Radiation Oncology, Gustave Roussy Cancer Campus, Villejuif, France
  • Johan Bussink Department of Radiation Oncology, Radboud University Medical Center, Nijmegen, The Netherlands
  • Corinne Faivre-Finn The Christie NHS Foundation Trust, Division of Cancer Science, The University of Manchester, Manchester, UK
  • Jonathan Khalifa Department of Radiotherapy, Institut Claudius Regaud/Institut Universitaire du Cancer de Toulouse - Oncopole, Toulouse, France
  • Anne Laprie Department of Radiotherapy, Institut Claudius Regaud/Institut Universitaire du Cancer de Toulouse - Oncopole, Toulouse, France
  • Yolande Lievens Radiation Oncology Department, Ghent University Hospital and Ghent University, Ghent, Belgium
  • Indira Madani Department of Radiation Oncology, University Hospital Zürich, Zürich, Switzerland
  • Amandine Ruffier Department of Radiation Oncology, Gustave Roussy Cancer Campus, Villejuif, France
  • Dirk de Ruysscher Department of Radiation Oncology (MAASTRO), GROW – School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, The Netherlands
  • Wouter van Elmpt Department of Radiation Oncology (MAASTRO), GROW – School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, The Netherlands
  • Esther G. C. Troost OncoRay – National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden - Rossendorf, Dresden, Germany;  Helmholtz-Zentrum Dresden - Rossendorf, Institute of Radiooncology – OncoRay, Dresden, Germany;  Department of Radiotherapy and Radiation Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany;  German Cancer Consortium (DKTK), Partner Site Dresden, and German Cancer Research Center DKFZ, Heidelberg, Germany;  National Center for Tumor Diseases (NCT), Partner Site Dresden, Germany: German Cancer Research Center (DKFZ), Heidelberg, Germany;  Faculty of Medicine, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany;  Helmholtz Association / Helmholtz-Zentrum Dresden - Rossendorf (HZDR), Dresden, Germany

DOI:

https://doi.org/10.1080/0284186X.2019.1629017

Abstract

Introduction: Inter-observer variability (IOV) in target volume delineation is a well-documented source of geometric uncertainty in radiotherapy. Such variability has not yet been explored in the context of adaptive re-delineation based on imaging data acquired during treatment. We compared IOV in the pre- and mid-treatment setting using expert primary gross tumour volume (GTV) and clinical target volume (CTV) delineations in locoregionally advanced head-and-neck squamous cell carcinoma (HNSCC) and (non-)small cell lung cancer [(N)SCLC].

Material and methods: Five and six observers participated in the HNSCC and (N)SCLC arm, respectively, and provided delineations for five cases each. Imaging data consisted of CT studies partly complemented by FDG-PET and was provided in two separate phases for pre- and mid-treatment. Global delineation compatibility was assessed with a volume overlap metric (the Generalised Conformity Index), while local extremes of IOV were identified through the standard deviation of surface distances from observer delineations to a median consensus delineation. Details of delineation procedures, in particular, GTV to CTV expansion and adaptation strategies, were collected through a questionnaire.

Results: Volume overlap analysis revealed a worsening of IOV in all but one case per disease site, which failed to reach significance in this small sample (p-value range .063–.125). Changes in agreement were propagated from GTV to CTV delineations, but correlation could not be formally demonstrated. Surface distance based analysis identified longitudinal target extent as a pervasive source of disagreement for HNSCC. High variability in (N)SCLC was often associated with tumours abutting consolidated lung tissue or potentially invading the mediastinum. Adaptation practices were variable between observers with fewer than half stating that they consistently adapted pre-treatment delineations during treatment.

Conclusion: IOV in target volume delineation increases during treatment, where a disparity in institutional adaptation practices adds to the conventional causes of IOV. Consensus guidelines are urgently needed.

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Published

2019-10-03

How to Cite

Apolle, R., Appold, S., Bijl, H. P., Blanchard, P., Bussink, J., Faivre-Finn, C., … Troost, E. G. C. (2019). Inter-observer variability in target delineation increases during adaptive treatment of head-and-neck and lung cancer. Acta Oncologica, 58(10), 1378–1385. https://doi.org/10.1080/0284186X.2019.1629017

Issue

Vol. 58 No. 10 (2019): Acta Oncologica

Section

Articles