title: Prospective evaluation of a hydrogel spacer for rectal separation in dose-escalated intensity-modulated radiotherapy for clinically localized prostate cancer.
abstract: BACKGROUND
  As dose-escalation in prostate cancer radiotherapy improves cure rates, a major concern is rectal toxicity. We prospectively assessed an innovative approach of hydrogel injection between prostate and rectum to reduce the radiation dose to the rectum and thus side effects in dose-escalated prostate radiotherapy.
  
  
  METHODS
  Acute toxicity and planning parameters were prospectively evaluated in patients with T1-2 N0 M0 prostate cancer receiving dose-escalated radiotherapy after injection of a hydrogel spacer. Before and after hydrogel injection, we performed MRI scans for anatomical assessment of rectal separation. Radiotherapy was planned and administered to 78 Gy in 39 fractions.
  
  
  RESULTS
  From eleven patients scheduled for spacer injection the procedure could be performed in ten. In one patient hydrodissection of the Denonvillier space was not possible. Radiation treatment planning showed low rectal doses despite dose-escalation to the target. In accordance with this, acute rectal toxicity was mild without grade 2 events and there was complete resolution within four to twelve weeks.
  
  
  CONCLUSIONS
  This prospective study suggests that hydrogel injection is feasible and may prevent rectal toxicity in dose-escalated radiotherapy of prostate cancer. Further evaluation is necessary including the definition of patients who might benefit from this approach.
  
  
  BACKGROUND
  German Clinical Trials Register DRKS00003273.
authors: Department of Radiation Oncology, Eberhard Karls University Tübingen, Hoppe-Seyler-Str. 3, Tübingen 72076, Germany.
authors: Franziska
authors: F
authors: Eckert
authors: Saladin
authors: S
authors: Alloussi
authors: Frank
authors: F
authors: Paulsen
authors: Michael
authors: M
authors: Bamberg
authors: Daniel
authors: D
authors: Zips
authors: Patrick
authors: P
authors: Spillner
authors: Cihan
authors: C
authors: Gani
authors: Ulrich
authors: U
authors: Kramer
authors: Daniela
authors: D
authors: Thorwarth
authors: David
authors: D
authors: Schilling
authors: Arndt-Christian
authors: AC
authors: Müller
mesh_terms: D000230:Adenocarcinoma / Q000097:blood / Q000473:pathology / Q000532:radiotherapy*; D000368:Aged; D019583:Dose Fractionation, Radiation; D005240:Feasibility Studies; D005858:Germany; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000008:administration & dosage*; D007267:Injections; D007610:Kallikreins / Q000097:blood; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D009367:Neoplasm Staging; D011446:Prospective Studies; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood / Q000473:pathology / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000209:etiology / Q000517:prevention & control*; D011880:Radiotherapy Planning, Computer-Assisted; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects; D012007:Rectum / Q000528:radiation effects*; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; C549870:KLK3 protein, human; D007610:Kallikreins; D017430:Prostate-Specific Antigen