title: Application of an interstitial and biodegradable balloon system for prostate-rectum separation during prostate cancer radiotherapy: a prospective multi-center study.
abstract: OBJECTIVE
  Rectal toxicity presents a significant limiting factor in prostate radiotherapy regimens. This study evaluated the safety and efficacy of an implantable and biodegradable balloon specifically designed to protect rectal tissue during radiotherapy by increasing the prostate-rectum interspace.
  
  
  METHODS
  Balloons were transperineally implanted, under transrectal ultrasound guidance, into the prostate-rectum interspace in 27 patients with localized prostate cancer scheduled to undergo radiotherapy. Patients underwent two simulations for radiotherapy planning--the first simulation before implant, and the second simulation seven days post implant. The balloon position, the dimensions of the prostate, and the distance between the prostate and rectum were evaluated by CT/US examinations 1 week after the implant, weekly during the radiotherapy period, and at 3 and 6 months post implant. Dose-volume histograms of pre and post implantation were compared. Adverse events were recorded throughout the study period.
  
  
  RESULTS
  Four of 27 patients were excluded from the evaluation. One was excluded due to a technical failure during implant, and three patients were excluded because the balloon prematurely deflated. The balloon status was evaluated for the duration of the radiotherapy period in 23 patients. With the balloon implant, the distance between the prostate and rectum increased 10-fold, from a mean 0.22 ± 0.2 cm to 2.47 ± 0.47 cm. During the radiotherapy period the balloon length changed from 4.25 ± 0.49 cm to 3.81 ± 0.84 cm and the balloon height from 1.86 ± 0.24 cm to 1.67 ± 0.22 cm. But the prostate-rectum interspace distance remained constant from beginning to end of radiotherapy: 2.47 ± 0.47 cm and 2.41 ± 0.43 cm, respectively. A significant mean reduction in calculated rectal radiation exposure was achieved. The implant procedure was well tolerated. The adverse events included mild pain at the perineal skin and in the anus. Three patients experienced acute urinary retention which resolved in a few hours following conservative treatment. No infections or thromboembolic events occurred during the implant procedure or during the radiotherapy period.
  
  
  CONCLUSIONS
  The transperineal implantation of the biodegradable balloon in patients scheduled to receive radiotherapy was safe and achieved a significant and constant gap between the prostate and rectum. This separation resulted in an important reduction in the rectal radiation dose. A prospective study to evaluate the acute and late rectal toxicity is needed.
authors.forename: Eliahu
authors.initials: E
authors.lastname: Gez
authors.forename: Shmuel
authors.initials: S
authors.lastname: Cytron
authors.forename: Rahamin
authors.initials: R
authors.lastname: Ben Yosef
authors.forename: Daniel
authors.initials: D
authors.lastname: London
authors.forename: Benjamin W
authors.initials: BW
authors.lastname: Corn
authors.forename: Shlomi
authors.initials: S
authors.lastname: Alani
authors.forename: Giovanni
authors.initials: G
authors.lastname: Scarzello
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Dal Moro
authors.forename: Guido
authors.initials: G
authors.lastname: Sotti
authors.forename: Filiberto
authors.initials: F
authors.lastname: Zattoni
authors.forename: Ike
authors.initials: I
authors.lastname: Koziol
authors.forename: Taryn
authors.initials: T
authors.lastname: Torre
authors.forename: Matthew
authors.initials: M
authors.lastname: Bassignani
authors.forename: Shalom
authors.initials: S
authors.lastname: Kalnicki
authors.forename: Reza
authors.initials: R
authors.lastname: Ghavamian
authors.forename: Dukagjin
authors.initials: D
authors.lastname: Blakaj
authors.forename: Mitchell
authors.initials: M
authors.lastname: Anscher
authors.forename: Martin
authors.initials: M
authors.lastname: Sommerauer
authors.forename: Dieter
authors.initials: D
authors.lastname: Jocham
authors.forename: Corinna
authors.initials: C
authors.lastname: Melchert
authors.forename: Stefan
authors.initials: S
authors.lastname: Huttenlocher
authors.forename: Gyoergy
authors.initials: G
authors.lastname: Kovacs
authors.forename: Madhur
authors.initials: M
authors.lastname: Garg
mesh_terms: D020341:Absorbable Implants; D000368:Aged; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011880:Radiotherapy Planning, Computer-Assisted; D012007:Rectum