title: Planning magnetic resonance imaging for prostate cancer intensity-modulated radiation therapy: Impact on target volumes, radiotherapy dose and androgen deprivation administration.
abstract: OBJECTIVE
  Magnetic resonance imaging (MRI) scans are increasingly utilized for radiotherapy planning to contour the primary tumors of patients undergoing intensity-modulated radiation therapy (IMRT). These scans may also demonstrate cancer extent and may affect the treatment plan. We assessed the impact of planning MRI detection of extracapsular extension, seminal vesicle invasion, or adjacent organ invasion on the staging, target volume delineation, doses, and hormonal therapy of patients with prostate cancer undergoing IMRT.
  
  
  METHODS
  The records of 509 consecutive patients with planning MRI scans being treated with IMRT for prostate cancer between January 2010 and July 2012 were retrospectively reviewed. Tumor staging and treatment plans before and after MRI were compared.
  
  
  RESULTS
  Of the 509 patients, 103 (20%) were upstaged and 44 (9%) were migrated to a higher risk category as a result of findings at MRI. In 94 of 509 patients (18%), the MRI findings altered management. Ninety-four of 509 patients (18%) had a change to their clinical target volume (CTV) or treatment technique, and in 41 of 509 patients (8%) the duration of hormone therapy was changed because of MRI findings.
  
  
  CONCLUSIONS
  The use of radiotherapy planning MRI altered CTV design, dose and/or duration of androgen deprivation in 18% of patients in this large, single institution series of men planned for dose-escalated prostate IMRT. This has substantial implications for radiotherapy target volumes and doses, as well as duration of androgen deprivation. Further research is required to investigate whether newer MRI techniques can simultaneously fulfill staging and radiotherapy contouring roles.
authors.affiliation: Department of Radiation Oncology, North Coast Cancer Institute, Coffs Harbour, New South Wales, Australia.
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Horsley
authors.forename: Noel J
authors.initials: NJ
authors.lastname: Aherne
authors.forename: Grace V
authors.initials: GV
authors.lastname: Edwards
authors.forename: Linus C
authors.initials: LC
authors.lastname: Benjamin
authors.forename: Shea W
authors.initials: SW
authors.lastname: Wilcox
authors.forename: Craig S
authors.initials: CS
authors.lastname: McLachlan
authors.forename: Hassan
authors.initials: H
authors.lastname: Assareh
authors.forename: Richard
authors.initials: R
authors.lastname: Welshman
authors.forename: Michael J
authors.initials: MJ
authors.lastname: McKay
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Shakespeare
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000726:Androgen Antagonists / Q000008:administration & dosage*; D059248:Chemoradiotherapy; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D009367:Neoplasm Staging; D011379:Prognosis; D011471:Prostatic Neoplasms / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D020266:Radiotherapy, Conformal / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012189:Retrospective Studies; D047368:Tumor Burden
chemical_list: D000726:Androgen Antagonists
keywords: IMRT; magnetic resonance imaging; prostate cancer; radiotherapy