Application of an interstitial and biodegradable balloon system for prostate-rectum separation during prostate cancer radiotherapy: a prospective multi-center study

Abstract

Background and purposeRectal 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.Patients and methodsBalloons 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.ResultsFour 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.ConclusionThe 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.

Physical and mechanical properties of PLA, and their functions in widespread applications — A comprehensive review

“…The balloon's safety and efficacy was established in a mammalian model and they have maintained their performance along the study followed by biodegradation without toxicity [304,305]. Recently, clinical studies have evaluated the safety and efficacy of these balloons for long term performance (up to 3 years of post-implantation) and the results were found promising, no safety issues were raised [306][307][308]. This example represents a good model for PLA property optimization and device fabrication to fulfill medical need, starting with proper polymer composition, implant degradability-mechanical stability balancing and proper sterilization technique development.…”

Fiducial markers and spacers in prostate radiotherapy: current applications

“…). Once inserted, it is inflated with saline and degradation starts at 3 months and completed usually by 6 months .…”

“…Gez et al. reported the use of a biodegradable balloon, ProSpace TM (Bioprotect, Israel) in 27 patients. In three patients, the balloon deflated prematurely (thought to be secondary to puncturing by previously implanted fiducials) and one could not be implanted because of technical failure.…”

Temporary organ displacement coupled with image-guided, intensity-modulated radiotherapy for paraspinal tumors

“…Slightly more invasive techniques have been examined in attempts to physically separate the rectum from the prostate in dose-escalation strategies for prostate cancer treatment. Approaches have included collagen and hyaluronic acid injections, as well as biodegradable balloon implantation between the rectum and prostate [4,5]. A prostate rectum separation of 10 mm significantly reduced mean V70 to the rectum by 83% (p<0.05), which should reduce chronic rectal toxicity [6].…”