title: Consequences of anorectal cancer atlas implementation in the cooperative group setting: radiobiologic analysis of a prospective randomized in silico target delineation study.
abstract: OBJECTIVE
  The aim of this study is to ascertain the subsequent radiobiological impact of using a consensus guideline target volume delineation atlas.
  
  
  METHODS
  Using a representative case and target volume delineation instructions derived from a proposed IMRT rectal cancer clinical trial, gross tumor volume (GTV) and clinical/planning target volumes (CTV/PTV) were contoured by 13 physician observers (Phase 1). The observers were then randomly assigned to follow (atlas) or not-follow (control) a consensus guideline/atlas for anorectal cancers, and instructed to re-contour the same case (Phase 2).
  
  
  RESULTS
  The atlas group was found to have increased tumor control probability (TCP) after the atlas intervention for both the CTV (p<0.0001) and PTV1 (p=0.0011) with decreasing normal tissue complication probability (NTCP) for small intestine, while the control group did not. Additionally, the atlas group had reduced variance in TCP for all target volumes and reduced variance in NTCP for the bowel. In Phase 2, the atlas group had increased TCP relative to the control for CTV (p=0.03).
  
  
  CONCLUSIONS
  Visual atlas and consensus treatment guideline usage in the development of rectal cancer IMRT treatment plans reduced the inter-observer radiobiological variation, with clinically relevant TCP alteration for CTV and PTV volumes.
authors.affiliation: Department of Radiation Oncology, The University of Texas Health Science Center at San Antonio, USA; Department of Oncology-Pathology, Karolinska Institutet and Stockholm University, Sweden. Electronic address: mavroidis@uthscsa.edu.
authors.forename: Panayiotis
authors.initials: P
authors.lastname: Mavroidis
authors.affiliation: Department of Radiation Oncology, Massachusetts General Hospital Cancer Center, Boston, USA.
authors.forename: Drosoula
authors.initials: D
authors.lastname: Giantsoudis
authors.affiliation: Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, USA.
authors.forename: Musaddiq J
authors.initials: MJ
authors.lastname: Awan
authors.affiliation: Department of Radiotherapy, The Netherlands Cancer Institute, Antoni van Leeuwenhoek Huis, Amsterdam, The Netherlands.
authors.forename: Jasper
authors.initials: J
authors.lastname: Nijkamp
authors.affiliation: Department of Radiotherapy, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: Coen R N
authors.initials: CR
authors.lastname: Rasch
authors.affiliation: Department of Radiotherapy, The Netherlands Cancer Institute, Antoni van Leeuwenhoek Huis, Amsterdam, The Netherlands.
authors.forename: Joop C
authors.initials: JC
authors.lastname: Duppen
authors.affiliation: Department of Radiation Medicine, Oregon Health & Science University, Portland, USA.
authors.forename: Charles R
authors.initials: CR
authors.lastname: Thomas
authors.affiliation: Department of Radiation Oncology, University of Florida, Gainesville, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Okunieff
authors.affiliation: Department of Radiation Oncology, The University of Texas Health Science Center at San Antonio, USA; Department of Radiation Oncology, Audie L. Murphy Veterans Administration Hospital, San Antonio, USA.
authors.forename: William E
authors.initials: WE
authors.lastname: Jones
authors.affiliation: Department of Radiation Oncology, Massachusetts General Hospital Cancer Center, Boston, USA; Department of Radiation Oncology, Boston University Medical Center, USA.
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Kachnic
authors.affiliation: Department of Radiation Oncology, The University of Texas Health Science Center at San Antonio, USA.
authors.forename: Niko
authors.initials: N
authors.lastname: Papanikolaou
authors.affiliation: Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, USA.
authors.forename: Clifton D
authors.initials: CD
authors.lastname: Fuller
mesh_terms: D003198:Computer Simulation; D032921:Consensus; D003299:Cooperative Behavior; D006801:Humans; D008297:Male; D015588:Observer Variation; D017410:Practice Guidelines as Topic; D011446:Prospective Studies; D011853:Radiobiology / Q000379:methods; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012004:Rectal Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D047368:Tumor Burden
keywords: Anorectal cancer; Atlas implementation; Inter-observer variation; Radiobiological analysis; Target delineation