title: Technique of Injection of Hyaluronic Acid as a Prostatic Spacer and Fiducials Before Hypofractionated External Beam Radiotherapy for Prostate Cancer.
abstract: OBJECTIVE
  To describe a technique combining the implantation of fiducials and a prostatic spacer (hyaluronic acid [HA]) to decrease the rectal toxicity after an image-guided external beam radiotherapy (EBRT) with hypofractionation for prostate cancer and to assess the tolerance and the learning curve of the procedure.
  
  
  METHODS
  Thirty patients with prostate cancer at low or intermediate risk were included in a phase II trial: image-guided EBRT of 62 Gy in 20 fractions of 3.1 Gy with intensity-modulated radiotherapy. A transrectal implantation of 3 fiducials and transperineal injection of 10 cc of HA (NASHA gel spacer, Q-Med AB, Uppsala, Sweden) between the rectum and the prostate was performed by 1 operator. The thickness of HA was measured at 10 points on magnetic resonance imaging to establish a quality score of the injection (maximum score = 10) and determine the learning curve of the procedure.
  
  
  RESULTS
  The quality score increased from patients 1-10, 11-20, to 21-30 with respective median scores: 7 [2-10], 5 [4-7], and 8 [3-10]. The average thicknesses of HA between the base, middle part, and apex of the prostate and the rectum were the following: 15.1 mm [6.4-29], 9.8 mm [5-21.2], and 9.9 mm [3.2-21.5]. The injection of the HA induced a median pain score of 4 [1-8] and no residual pain at mid-long term.
  
  
  CONCLUSIONS
  Creating an interface between the rectum and the prostate and the implantation of fiducials were feasible under local anesthesia with a short learning curve and could become a standard procedure before a hypofractionated EBRT for prostate cancer.
authors.affiliation: Université Lyon 1, Lyon, France; Department of Urology, Hospices Civils de Lyon, Centre Hospitalier Lyon Sud, Pierre Benite, France. Electronic address: romain.boissier@ap-hm.fr.
authors.forename: Romain
authors.initials: R
authors.lastname: Boissier
authors.affiliation: Department of Radiation Oncology, Hospices Civils de Lyon, Centre Hospitalier Lyon Sud, Pierre Benite, France; EMR3738, Université Lyon 1, Lyon, France.
authors.forename: Corina
authors.initials: C
authors.lastname: Udrescu
authors.affiliation: Department of Urology, Clinique Beausoleil, Montpellier, France.
authors.forename: Xavier
authors.initials: X
authors.lastname: Rebillard
authors.affiliation: Université Lyon 1, Lyon, France; Department of Urology, Hospices Civils de Lyon, Centre Hospitalier Lyon Sud, Pierre Benite, France.
authors.forename: Jean-Etienne
authors.initials: JE
authors.lastname: Terrier
authors.affiliation: Department of Urology, Clinique Beausoleil, Montpellier, France.
authors.forename: Antoine
authors.initials: A
authors.lastname: Faix
authors.affiliation: Department of Radiation Oncology, Hospices Civils de Lyon, Centre Hospitalier Lyon Sud, Pierre Benite, France; EMR3738, Université Lyon 1, Lyon, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Chapet
authors.affiliation: Department of Radiation Oncology and Physics, Institut du Cancer de Montpellier, Montpellier, France.
authors.forename: David
authors.initials: D
authors.lastname: Azria
authors.affiliation: Université Lyon 1, Lyon, France; Department of Urology, Hospices Civils de Lyon, Centre Hospitalier Lyon Sud, Pierre Benite, France.
authors.forename: Marian
authors.initials: M
authors.lastname: Devonec
authors.affiliation: Université Lyon 1, Lyon, France; Department of Urology, Hospices Civils de Lyon, Centre Hospitalier Lyon Sud, Pierre Benite, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Paparel
authors.affiliation: Université Lyon 1, Lyon, France; Department of Urology, Hospices Civils de Lyon, Centre Hospitalier Lyon Sud, Pierre Benite, France.
authors.forename: Alain
authors.initials: A
authors.lastname: Ruffion
mesh_terms: D000368:Aged; D019583:Dose Fractionation, Radiation; D019160:Endosonography; D057918:Fiducial Markers; D006801:Humans; D006820:Hyaluronic Acid / Q000008:administration & dosage*; D007267:Injections; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011467:Prostate; D011471:Prostatic Neoplasms / Q000175:diagnosis / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000517:prevention & control*; D061089:Radiotherapy, Image-Guided / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012007:Rectum; D016896:Treatment Outcome; D055675:Viscosupplements / Q000008:administration & dosage
chemical_list: D055675:Viscosupplements; D006820:Hyaluronic Acid