195 - Long-Term Toxicity and Patient-Reported Quality of Life after Prostate IMRT with or without Biodegradable Balloon Rectal Spacer: Analysis of a Pivotal Randomized Trial

11:05am - 11:15am PT

Room 156/158

Presenter(s)

Daniel Song, MD - Johns Hopkins University, Baltimore, MD

D. Song¹, M. Dabkowski², I. Shpunt³, E. Sapir⁴, E. V. Limbergen⁵, A. V. Boychak⁶, P. Costa⁷, D. Margel⁸, E. M. Soffen⁹, R. Hudes¹⁰, and Z. Shawn¹¹; ¹Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, ²Brachytherapy Department, Center of Oncology, M. Sklodowska-Curie Memorial Institute, Warsaw, Poland, ³Rabin Medical Center, PetahTikva, Israel, ⁴Radiation Oncology Institute, Samson Assuta Ashdod University Hospital, Ashdod, Israel, ⁵MAASTRO Clinic Dr. Tanslaan, Maastricht, Netherlands, ⁶St Luke’s Hospital, Rathgar, Dublin, Ireland, ⁷CUF Porto Instituto Rua Fontedas Sete Bicas, Senhora da Hora Matosinhos, Portugal, ⁸Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel, ⁹Princeton Radiation Oncology, Astera Cancer Care, Jamesburg, NJ, ¹⁰Chesapeake Urology Research, Owings Mills, MD, ¹¹Advanced Radiation Centers of NewYork, Lake Success, NY

Purpose/Objective(s):

Prostatic-rectal spacers have been shown to improve rectal dosimetry and acute rectal toxicity for patients receiving prostate radiotherapy. Long-term outcomes are needed to determine whether these benefits are maintained over time.

The hypothesis is that long-term toxicity and quality of life are improved with the use of a prostatic-rectal spacer balloon.

Materials/Methods:

A total of 222 men with prostate cancer were enrolled in a multi-institutional trial and randomized 2:1 to fiducial marker-based IG-IMRT with or without a biodegradable balloon spacer placed into Denonvilliers’ fascia. Planned secondary outcomes of toxicity and quality of life (QOL) were available from 164 subjects over 48 months. Cumulative toxicity (CTCAE v4.0) was evaluated using log-rank test. Patient-reported QOL (EPIC-26), and mean changes from baseline were analyzed using repeated measures models. The proportion exceeding minimally important difference (MID) thresholds (bowel 5, urinary irritative 6, incontinence 12, sexual 11) were tested using logistic models.

Results:

At median follow-up 32.8 months, cumulative incidence of CTCAE grade =1 (14.2% vs 29.5%, p<.01) and grade =2 (6.9% vs 15.8%, p=.03) rectal toxicity favored the balloon group. Urinary toxicity was also lower with the balloon (grade =1: 20.2% vs 42.4%, p<.01; grade =2: 10.6% vs 22.3%, p=.03). Sexual toxicity trended lower but was not significant (grade =1: 12.9% vs 19.9%, p=.28; grade =2: 10.3% vs 14.7%, p=.49).

From 6 months onward, mean change from baseline in patient-reported bowel QOL was superior for balloon group, reaching an 8.7-point difference (balloon vs. control) at 48 months (p=.01). Urinary irritative, urinary incontinence, and sexual QOL preservation were also superior in balloon group, with 48-month differences between groups of 9.3 (p=.01), 12.3 (p<0.01), and 15.9 points (p=.01), respectively.

At 48 months, more men in control group experienced a MID decline in bowel (19% vs 10%; p=.10), urinary irritative (34% vs 30%; p=.48), and urinary incontinence domains (32% vs 18%; p=.04). Based on a previously established threshold, men were dichotomized on baseline sexual function domain score of >60 or =60. Among men with baseline EPIC sexual >60, MID declines were significantly more frequent in the control group (35% vs 20%, p<.01). In those with baseline EPIC sexual =60, MID decline was also more frequent in controls (35% vs 19%, p=.01).

Conclusion:

Use of balloon rectal spacer resulted in reduced long-term rectal adverse events and better patient-reported bowel outcomes after IMRT. Benefits of spacer were not limited to rectal function but also resulted in improved preservation of urinary and sexual domains. To our knowledge, these are the first randomized data to demonstrate improvements in sexual QOL outcomes with rectal spacer. Balloon rectal spacers should be considered as a means to reduce long-term toxicity and minimize QOL impact for patients undergoing IMRT for prostate cancer.