BERKELEY, CA (UroToday.com) - This meta-analysis examined the outcomes of American Medical Systems artificial urinary sphincter (AUS) on patients undergoing prior external beam radiotherapy and patients not undergoing adjuvant radiotherapy (EBRT). The authors found increased risk for surgical revisions and urinary incontinence which had not resolved following implantation in men receiving EBRT. The primary causes for device failure and replacement were urethral atrophy and infection-erosion. This study is the first to show that EBRT is a risk factor for poorer outcomes, and provides clinicians and patients level ‘2a’ evidence according to the Oxford Evidence-Based Criteria.
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A high level of heterogeneity was found between cohorts examined for surgical revisions which might be attributed to the varied practices of implantation and pre-operative characteristics, including surgical approach and intensity of EBRT received by patients. The impact of prostate cancer stage and margin status on device survival was not examined in this analysis and may further have contributed to heterogeneity. Publication bias in favour of positive outcomes in EBRT patients was also detected, however not for persistent UI outcomes. This might reflect chance finding or a preponderance of favourable cohort results being prepared for publication.
In the present analysis, it was not possible to perform subgroup analyses and stratify patients by disease stage, EBRT dose and technique, co-morbidities, and pre-existing revision surgeries to the AUS. Limitations to the data presented included the lack of incorporation in cohorts of a standardised quality of life outcome measure for overall device satisfaction and also a validated urinary incontinence (UI) questionnaire that accurately quantifies volumetric UI. Follow up varied from 20 – 68 months in the 16 studies included. This reflects a generalised deficiency of long-term follow up in the literature.
The AUS is the gold standard for UI following RP. However, robotic procedures are increasingly undertaken, and therefore the incidence of post RP-UI may indeed fall in the coming years. Furthermore, modern radiotherapy offers diminished collateral pelvic irradiation. Because the studies we used to construct our analysis dated from 1989 to the present, some degree of improvement in tissue viability in patients may be observed in contemporary cohorts. Clinically, however, this remains to be demonstrated in outcomes of the AUS. It may be that as open RP is reserved for the more extensive disease resections; the AUS will remain as a treatment option in less favourable RP continence outcomes for both robotic and open procedures. The male sling also vies for use in the same group following RP, and the MASTER trial in the United Kingdom will seek to address the efficacy of these devices in post RP UI. The trial is a prospective and randomised controlled trial assessing the efficacy of the sling versus other post RP UI interventions.
In conclusion, this study is the first to quantify the risk EBRT poses to men undergoing AUS implantation following RP for UI, with regards to device revision and failure. Our work provides a high level of evidence from pooled data, however bias associated with retrospective analysis must not be discarded. Indeed a variables correlation alone cannot be accredited to cause, yet this work strongly suggests that patients receiving EBRT are at a higher risk of device revisions and unresolved UI. This evidence thus deserves a place in the planning of future trials, follow up, audit and patient counseling.
Anthony S. Bates and Tim R. Terry as part of Beyond the Abstract on UroToday.com. This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.
Department of Urology, Leicester General Hospital, University Hospitals of Leicester NHS Trust, United Kingdom