title: The influence of dose distribution on treatment outcome in the SCOPE 1 oesophageal cancer trial.
abstract: OBJECTIVE
  The first aim of this study was to assess plan quality using a conformity index (CI) and analyse its influence on patient outcome. The second aim was to identify whether clinical and technological factors including planning treatment volume (PTV) volume and treatment delivery method could be related to the CI value.
  
  
  METHODS
  By extending the original concept of the mean distance to conformity (MDC) index, the OverMDC and UnderMDC of the 95 % isodose line (50Gy prescribed dose) to the PTV was calculated for 97 patients from the UK SCOPE 1 trial (ISCRT47718479). Data preparation was carried out in CERR, with Kaplan-Meier and multivariate analysis undertaken in EUCLID and further tests in Microsoft Excel and IBM's SPSS.
  
  
  RESULTS
  A statistically significant breakpoint in the overall survival data, independent of cetuximab, was found with OverMDC (4.4 mm, p < 0.05). This was not the case with UnderMDC. There was a statistically significant difference in PTV volume either side of the OverMDC breakpoint (Mann Whitney p < 0.001) and in OverMDC value dependent on the treatment delivery method (mean IMRT = 2.1 mm, mean 3D-CRT = 4.1 mm Mann Whitney p < 0.001). Re-planning the worst performing patients according to OverMDC from 3D-CRT to VMAT resulted in a mean reduction in OverMDC of 2.8 mm (1.6-4.0 mm). OverMDC was not significant in multivariate analysis that included age, sex, staging, tumour type, and position.
  
  
  CONCLUSIONS
  Although not significant when included in multivariate analysis, we have shown in univariate analysis that a patient's OverMDC is correlated with overall survival. OverMDC is strongly related to IMRT and to a lesser extent with PTV volume. We recommend that VMAT planning should be used for oesophageal planning when available and that attention should be paid to the conformity of the 95 % to the PTV.
authors: School of Medicine, Cardiff University, Cardiff, UK. carringtondr@cardiff.ac.uk.
authors: Rhys
authors: R
authors: Carrington
authors: School of Engineering, Cardiff University, Cardiff, UK. espezi@cardiff.ac.uk.
authors: Emiliano
authors: E
authors: Spezi
authors: South West Wales Cancer Centre, Swansea, UK. Sarah.Gwynne@wales.nhs.uk.
authors: Sarah
authors: S
authors: Gwynne
authors: Wales Cancer Trials Unit, Cardiff University, Cardiff, UK. duttonp@cardiff.ac.uk.
authors: Peter
authors: P
authors: Dutton
authors: Wales Cancer Trials Unit, Cardiff University, Cardiff, UK. hurtcn@cardiff.ac.uk.
authors: Chris
authors: C
authors: Hurt
authors: Department of Clinical Oncology, Velindre Cancer Centre, Cardiff, UK. john.staffurth@wales.nhs.uk.
authors: John
authors: J
authors: Staffurth
authors: Department of Clinical Oncology, Velindre Cancer Centre, Cardiff, UK. tom.crosby@wales.nhs.uk.
authors: Thomas
authors: T
authors: Crosby
mesh_terms: D000465:Algorithms; D000068818:Cetuximab / Q000008:administration & dosage; D004938:Esophageal Neoplasms / Q000401:mortality / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D053208:Kaplan-Meier Estimate; D008297:Male; D015999:Multivariate Analysis; D016016:Proportional Hazards Models; D011829:Radiation Dosage; D011874:Radiometry / Q000379:methods; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D016896:Treatment Outcome
chemical_list: D000068818:Cetuximab