title: The effect of dose escalation on gastric toxicity when treating lower oesophageal tumours: a radiobiological investigation.
abstract: OBJECTIVE
  Using radiobiological modelling to estimate normal tissue toxicity, this study investigates the effects of dose escalation for concurrent chemoradiation therapy (CRT) in lower third oesophageal tumours on the stomach.
  
  
  METHODS
  10 patients with lower third oesophageal cancer were selected from the SCOPE 1 database (ISCRT47718479) with a mean planning target volume (PTV) of 348 cm(3). The original 3D conformal plans (50 Gy3D) were compared to newly created RapidArc plans of 50 GyRA and 60 GyRA, the latter using a simultaneous integrated boost (SIB) technique using a boost volume, PTV2. Dose-volume metrics and estimates of normal tissue complication probability (NTCP) were compared.
  
  
  RESULTS
  There was a significant increase in NTCP of the stomach wall when moving from the 50 GyRA to the 60 GyRA plans (11-17 %, Wilcoxon signed rank test, p = 0.01). There was a strong correlation between the NTCP values of the stomach wall and the volume of the stomach wall/PTV 1 and stomach wall/PTV2 overlap structures (R = 0.80 and R = 0.82 respectively) for the 60 GyRA plans.
  
  
  CONCLUSIONS
  Radiobiological modelling suggests that increasing the prescribed dose to 60 Gy may be associated with a significantly increased risk of toxicity to the stomach. It is recommended that stomach toxicity be closely monitored when treating patients with lower third oesophageal tumours with 60 Gy.
authors.affiliation: School of Medicine, Cardiff University, Cardiff, UK. carringtondr@cardiff.ac.uk.
authors.forename: Rhys
authors.initials: R
authors.lastname: Carrington
authors.affiliation: Department of Clinical Oncology, Velindre Cancer Centre, Cardiff, UK. john.staffurth@wales.nhs.uk.
authors.forename: John
authors.initials: J
authors.lastname: Staffurth
authors.affiliation: CRUK MRC Oxford Institute for Radiation Oncology Gray Laboratories, University of Oxford, Old Road Campus Research Building, Oxford, UK. samantha.warren@oncology.ox.ac.uk.
authors.forename: Samantha
authors.initials: S
authors.lastname: Warren
authors.affiliation: CRUK MRC Oxford Institute for Radiation Oncology Gray Laboratories, University of Oxford, Old Road Campus Research Building, Oxford, UK. mike.partridge@oncology.ox.ac.uk.
authors.forename: Mike
authors.initials: M
authors.lastname: Partridge
authors.affiliation: Wales Cancer Trials Unit, Cardiff University, Cardiff, UK. HurtCN@cardiff.ac.uk.
authors.forename: Chris
authors.initials: C
authors.lastname: Hurt
authors.affiliation: School of Engineering, Cardiff University, Cardiff, UK. espezi@cardiff.ac.uk.
authors.forename: Emiliano
authors.initials: E
authors.lastname: Spezi
authors.affiliation: South West Wales Cancer Centre, Swansea, UK. Sarah.Gwynne@wales.nhs.uk.
authors.forename: Sarah
authors.initials: S
authors.lastname: Gwynne
authors.affiliation: CRUK MRC Oxford Institute for Radiation Oncology Gray Laboratories, University of Oxford, Old Road Campus Research Building, Oxford, UK. maria.hawkins@oncology.ox.ac.uk.
authors.forename: Maria A
authors.initials: MA
authors.lastname: Hawkins
authors.affiliation: School of Medicine, Cardiff University, Cardiff, UK. Tom.Crosby@wales.nhs.uk.
authors.forename: Thomas
authors.initials: T
authors.lastname: Crosby
mesh_terms: D004938:Esophageal Neoplasms / Q000532:radiotherapy*; D006801:Humans; D008962:Models, Theoretical; D058958:Organs at Risk / Q000528:radiation effects; D011832:Radiation Injuries / Q000517:prevention & control; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D020266:Radiotherapy, Conformal / Q000379:methods*; D013270:Stomach / Q000528:radiation effects*