Hypothesis / aims of study
Prior data suggests radiation is associated with shorter artificial urinary sphincter (AUS) device survival. However, there is a paucity of data on outcomes of patients who undergo radiation after AUS. Thus, we aimed to compare AUS outcomes between patients receiving prostate radiation before or after AUS placement.
Study design, materials and methods
After IRB approval, we utilized our institutional Partners Research Patient Data Registry to identify all men who underwent AUS, radical prostatectomy and prostate radiation from 1989-2019 with any surgeon. After these patients were identified, we undertook a retrospective chart review to collect demographic and clinical information. Patients were grouped by radiation before or after AUS and clustered by surgeon. Our primary outcomes were diagnosis of urethral atrophy – recurrent incontinence with functional device – and revision surgery for atrophy as well as time to these outcomes. Time to outcome was calculated from the date by which patients had received both AUS and radiation. We performed univariate, multivariable logistic and Cox proportional hazard survival analyses.
We identified 154 patients meeting our study criteria. Of these men, 137 (88.96%) underwent radiation a median 48 mo (3-267) prior to AUS. 17 patients (11.04%) underwent radiation after AUS at a median 16.5 mo (2-77). There was no difference in age, race, Charlson Comorbidity Index, smoking, diabetes, prior male urethral sling, prior endoscopic bulking agent injection, pre-existing bladder neck contracture, androgen deprivation, or AUS cuff size between groups. Median follow-up post-exposure was 25 (0-216) mo.
Atrophy occurred in significantly more men in the radiation after AUS group (47.0% v 10.2%, p=<0.001) at a median 12.0 vs. 35.5 mo (p=0.04). Our multivariable regression including all collected variables revealed that receipt of radiation after AUS (OR 6.73, p<0.001) was associated with recurrent incontinence due to atrophy. Previous or current smoking (OR 1.40, p=0.02), previous urethral sling (OR 2.32, p<0.001) and increased size of AUS cuff (OR 4.08, p=0.02) were also associated with atrophy on multivariable analysis.
Multivariable survival analysis demonstrated that those with radiation after AUS developed atrophy earlier (12.0 mo vs 35.5 mo, HR 4.02, p=0.04) and had a shorter time to device revision for atrophy (57.0 mo vs 45.5 mo, HR 9.2, p=0.003). There was no difference in urologic complications, erosion, explant or revision between those undergoing AUS before or after radiation on either univariate or multivariable analysis.
Interpretation of results
While there was no difference of overall post-operative urologic complications between pre-AUS radiation and post-AUS radiation patients in this small cohort study, we found that post-AUS radiation is associated with higher rates of atrophy and revision for atrophy as well as shorter time to device revision for atrophy.