title: Evaluation of normal tissue exposure in patients receiving radiotherapy for pancreatic cancer based on RTOG 0848.
abstract: BACKGROUND
  Pancreatic cancer is a highly aggressive malignancy. Chemoradiotherapy (CRT) is utilized in many cases to improve locoregional control; however, toxicities associated with radiation can be significant given the location of the pancreas. RTOG 0848 seeks to evaluate chemoradiation using either intensity-modulated radiation therapy (IMRT) or 3D conformal photon radiotherapy (3DCRT) modalities as an adjuvant treatment. The purpose of this study is to quantify the dosimetric changes seen when using IMRT or 3D CRT photon modalities, as well as proton radiotherapy, in patients receiving CRT for cancer of the pancreas treated per RTOG 0848 guidelines.
  
  
  METHODS
  Ten patients with pancreatic head adenocarcinoma treated between 2010 and 2013 were evaluated in this study. All patients were simulated with contrast-enhanced CT imaging. Separate treatment plans using IMRT and 3DCRT as well as proton radiotherapy were created for each patient. All planning volumes were created per RTOG 0848 protocol. Dose-volume histograms (DVH) were calculated and analyzed in order to compare plans between the three modalities. The organs at risk (OAR) evaluated in this study are the kidneys, liver, small bowel, and spinal cord.
  
  
  RESULTS
  There was no difference between the IMRT and 3DCRT plans in dose delivered to the kidneys, liver, or bowel. The proton radiotherapy plans were found to deliver lower mean total kidney doses, mean liver doses, and liver D1/3 compared to the IMRT plans. The proton plans also gave less mean liver dose, liver D1/3, bowel V15, and bowel V50 in comparison to the 3DCRT.
  
  
  CONCLUSIONS
  For patients receiving radiotherapy per ongoing RTOG 0848 for pancreatic cancer, there was no significant difference in normal tissue sparing between IMRT and 3DCRT treatment planning. Therefore, the choice between the two modalities should not be a confounding factor in this study. The proton plans also demonstrated improved OAR sparing compared to both IMRT and 3DCRT treatment plans.
authors.affiliation: Department of Radiation Medicine, Loma Linda University Medical Center, Loma Linda, California, USA.
authors.forename: Ted C
authors.initials: TC
authors.lastname: Ling
authors.affiliation: Department of Radiation Medicine, Loma Linda University Medical Center, Loma Linda, California, USA.
authors.forename: Jerry M
authors.initials: JM
authors.lastname: Slater
authors.affiliation: Department of Radiation Medicine, Loma Linda University Medical Center, Loma Linda, California, USA.
authors.forename: Rachel
authors.initials: R
authors.lastname: Mifflin
authors.affiliation: Department of Radiation Medicine, Loma Linda University Medical Center, Loma Linda, California, USA.
authors.forename: Prashanth
authors.initials: P
authors.lastname: Nookala
authors.affiliation: Department of Radiation Medicine, Loma Linda University Medical Center, Loma Linda, California, USA.
authors.forename: Roger
authors.initials: R
authors.lastname: Grove
authors.affiliation: Department of Radiation Medicine, Loma Linda University Medical Center, Loma Linda, California, USA.
authors.forename: Anh M
authors.initials: AM
authors.lastname: Ly
authors.affiliation: Department of Radiation Medicine, Loma Linda University Medical Center, Loma Linda, California, USA.
authors.forename: Baldev
authors.initials: B
authors.lastname: Patyal
authors.affiliation: Department of Radiation Medicine, Loma Linda University Medical Center, Loma Linda, California, USA.
authors.forename: Jerry D
authors.initials: JD
authors.lastname: Slater
authors.affiliation: Department of Radiation Medicine, Loma Linda University Medical Center, Loma Linda, California, USA.
authors.forename: Gary Y
authors.initials: GY
authors.lastname: Yang
keywords: Pancreatic cancer; RTOG 0848; intensity-modulated radiation therapy (IMRT); proton radiotherapy
references.citation: Radiother Oncol. 2010 Jan;94(1):60-6
references.pmid: 19896229
references.citation: Int J Radiat Oncol Biol Phys. 2002 Jan 1;52(1):176-83
references.pmid: 11777636
references.citation: Int J Radiat Oncol Biol Phys. 2012 May 1;83(1):158-63
references.pmid: 22245197
references.citation: Radiother Oncol. 2007 Feb;82(2):174-8
references.pmid: 17275112
references.citation: Int J Radiat Oncol Biol Phys. 2006 Oct 1;66(2):505-13
references.pmid: 16879928
references.citation: Int J Radiat Oncol Biol Phys. 2007 Aug 1;68(5):1557-66
references.pmid: 17544599
references.citation: Anticancer Res. 2006 Sep-Oct;26(5B):3755-9
references.pmid: 17094397
references.citation: CA Cancer J Clin. 2006 Mar-Apr;56(2):106-30
references.pmid: 16514137
references.citation: Int J Radiat Oncol Biol Phys. 2008 Jun 1;71(2):603-10
references.pmid: 18474316
references.citation: Int J Radiat Oncol Biol Phys. 1991 May 15;21(1):109-22
references.pmid: 2032882
references.citation: Int J Radiat Oncol Biol Phys. 2011 Jan 1;79(1):158-62
references.pmid: 20399035
references.citation: Int J Radiat Oncol Biol Phys. 2011 Jan 1;79(1):151-7
references.pmid: 20421151
references.citation: Radiother Oncol. 2008 Jul;88(1):34-45
references.pmid: 18395811
references.citation: Br J Radiol. 2008 Apr;81(964):333-40
references.pmid: 18344277
references.citation: Radiother Oncol. 2009 Aug;92(2):238-43
references.pmid: 19454367