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

BACKGROUND AND PURPOSE: 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. PATIENTS AND 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. CONCLUSION: 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.

Interstitial biodegradable balloon for reduced rectal dose during prostate radiotherapy: results of a virtual planning investigation based on the pre- and post-implant imaging data of an international multicenter study.

PURPOSE: To evaluate dose reduction caused by the implantation of an interstitial inflatable and biodegradable balloon device aiming to achieve lower rectal doses with virtual 3D conformal external beam radiation treatment. MATERIALS AND METHODS: An inflatable balloon device was placed, interstitially and under transrectal ultrasound guidance, into the rectal-prostate interspace prior treatment initiation of 26 patients with localized prostate cancer, who elected to be treated with radiotherapy (3D CRT or IMRT). The pre- and post-implant CT imaging data of twenty two patients were collected (44 images) for the purpose of the 3D conformal virtual planning presented herein. RESULTS: The dorsal prostate-ventral rectal wall separation resulted in an average reduction of the rectal V70% by 55.3% (± 16.8%), V80% by 64.0% (± 17.7%), V90% by 72.0% (± 17.1%), and V100% by 82.3% (± 24.1%). In parallel, rectal D2 ml and D0.1 ml were reduced by 15.8% (± 11.4%) and 3.9% (± 6.4%), respectively. CONCLUSIONS: Insertion of the biodegradable balloon into the prostate-rectum interspace is similar to other published invasive procedures. In this virtual dose distribution analysis, the balloon insertion resulted in a remarkable reduction of rectal volume exposed to high radiation doses. This effect has the potential to keep the rectal dose lower especially when higher than usual prostate dose escalation protocols or hypo-fractionated regimes are used. Further prospective clinical investigations on larger cohorts and more conformal radiation techniques will be necessary to define the clinical advantage of the biodegradable interstitial tissue separation device.

Prognostic significance of race on biochemical control in patients with localized prostate cancer treated with permanent brachytherapy: multivariate and matched-pair analyses.

PURPOSE: To compare PSA relapse-free survival (PSA-RFS) between African-American (AA) and white American (WA) males treated with permanent prostate brachytherapy (PPB) for clinically localized prostate cancer. METHODS AND MATERIALS: One thousand eighty-one consecutive patients, including 246 African-Americans, underwent PPB with 103Pd or 125I, alone or with external beam radiation therapy between September 1992 and September 1999. Computer-generated matching was performed to create two identical cohorts of WA and AA males, based on the use of neoadjuvant androgen ablation (NAAD), pretreatment PSA, and Gleason score. Presenting characteristics were used to define risk groups, as follows: Low risk had PSA 10 or Gleason score >or=7, and high risk had PSA >10 and Gleason score >or=7. PSA-RFS was calculated using the Kattan modification of the ASTRO definition, and the log-rank test was used to compare Kaplan-Meier PSA-RFS curves. Univariate and multivariate analyses were performed to determine predictors of PSA-RFS. RESULTS: Overall, univariate analysis revealed that AA males at presentation had lower disease stage (p = 0.01), had lower Gleason scores (p = 0.017), were younger (p = 0.001), and were more likely to receive NAAD (p = 0.001) than their WA counterparts. There were no differences in pretreatment PSA, isotope selection, use of external beam radiation therapy, median follow-up, or risk group classification between AA and WA males. Pretreatment PSA and Gleason score were significant predictors of PSA-RFS in multivariate analysis, and race was not significant. There was no significant difference between the 5-year PSA-RFS for AA males (84.0%) and the matched cohort of WA males (81.2%) (p = 0.384). Race was not a predictor of 5-year PSA-RFS among patients treated with or without NAAD and within low-, intermediate-, and high-risk groups. CONCLUSION: Race is not an independent predictor of 5-year PSA-RFS in patients with localized prostate cancer treated with PPB. This result is consistent with other studies that also show that race does not contribute to differences in outcome after definitive therapies for localized prostate cancer.