Impact of Adjuvant Radiation on Artificial Urinary Sphincter Durability in Post-Prostatectomy Patients - Beyond the Abstract

Stress urinary incontinence affects up to 40% of patients after prostatectomy, representing a significant burden on quality of life. Artificial urinary sphincter (AUS) placement remains the gold standard treatment for post-prostatectomy stress urinary incontinence, as it replaces the patient’s diminished external sphincter. While AUS outcomes in post-prostatectomy patients have been commonly described, there remains a dearth of detailed evidence pertaining to those receiving both prostatectomy and adjuvant radiation. Over 10% of post-prostatectomy patients will receive adjuvant radiation treatment for further oncologic management. We aimed to quantify the relative effects of adjuvant radiation on those who require AUS placement after prostatectomy.

Our study produced several interesting findings. Adjuvant radiation significantly predicted AUS device failure (Hazard Ratio (HR) = 4.32, p<0.01). Patients undergoing radiotherapy had markedly decreased revision-free survival at 5 years compared to their counterparts not undergoing radiation (44.5% vs. 70.6%, p<0.01). When stratifying failure by cause, interestingly, we found that adjuvant radiation does not significantly increase the risk of mechanical failure (HR = 2.12, p = 0.09) or urethral atrophy (HR = 1.48, p = 0.49). However, radiated patients have higher risk of infection or erosion (HR = 4.48, p = 0.03). Thus, the increases in infection and erosion primarily constitute the difference in all-cause AUS device failure between the radiation and non-radiation groups. Lastly, we identified a particularly high risk group of patients – those with urethral comorbidities as well as adjuvant radiation history. Among this group, we found such patients had notably poor outcomes with only 22.4% revision-free survival at 3 years.

We believe our article contributes to the existing AUS literature in several ways. First, with over 150 patients, we provide one of the larger studies to date to specifically study adjuvant radiotherapy’s effect on the AUS related outcomes. Secondly, to the authors’ knowledge this is the first study to stratify device failure in to three categories – Mechanical Failure, Urethral Atrophy, and Infection/Erosion – using competing risks regression. Lastly, our paper is the first to examine the intersection of the urethral comorbidities (i.e. urethral stricture, bladder neck contracture, and prior urethral sling placement), adjuvant radiation, and AUS placement.

While AUS placement remains a very effective treatment for stress urinary incontinence, our study helps providers identify patients who may be poor candidates for such treatments. Patients with history of adjuvant radiation seem to have increased rate of revision-free survival, specifically due to increases in infection and erosion. Furthermore, providers should consider prior urethral exposures and damage, as urethral comorbidities may also contribute to poor device outcomes.

Written by:
Arnav Srivastava MPH1*, Gregory A. Joice MD1*, Hiten D. Patel MD MPH1, Madeleine G. Manka MD2, Nikolai A. Sopko MD PhD1, E. James Wright MD1

1 James Buchanan Brady Urological Institute, Johns Hopkins Hospital, Baltimore, MD
2 Department of Urology, Mayo Clinic, Rochester MN, USA

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