POINT-COUNTERPOINT Posterior Urethral Stenosis After Prostate Cancer Radiotherapy, What Is the Best Perineal Approach: Dorsal Buccal Onlay
By: Dmitriy Nikolavsky, MD, SUNY Upstate Medical University, Syracuse, New York | Posted on: 25 Oct 2023
In describing the optimal approach for posterior urethral stenosis after radiotherapy, or after procedures for benign prostatic hyperplasia, the goals and principles to the surgical approach would include (1) relief of the patient’s obstruction with improvement in symptoms, (2) preservation of continence, (3) minimal urethral dissection/mobilization, (4) preservation of bulbar blood supply (by avoiding transection), (5) avoidance of dissection near the radiated rectum, especially in patients with prior prostatectomy, and (6) avoidance of an anastomosis between a radiated proximal segment and distal urethral segment with compromised vascularity. In that context, I would argue that excision and primary anastomosis (EPA) is the opposite of the “ideal” or “intelligently designed” technique for a radiated urethral stenosis. The EPA and associated gap-bridging maneuvers were designed as an operation for a different disease: the traumatically disrupted urethra, where the scarring occurs at the site of injury and must be excised, allowing anastomosis of the patent/healthy (unirradiated) urethral lumens. Importantly, patients with urethral scar secondary to trauma often have more than adequate urethral blood supply both proximal and distal to the area of traumatic insult. In patients with posterior urethral stenosis following radiation therapy, however, the urethral segment proximal to the stenosis is often affected by radiation therapy and thus has impaired blood supply. This is a key difference between these patient populations and further disruption of urethral blood supply with transection via EPA urethroplasty would only portend worse outcomes than substitution urethroplasty.
Accordingly, some of the largest series reporting outcomes following transecting EPA for radiation induced urethral strictures have demonstrated notably lower rates of success compared to nonradiated counterparts.1-5 Also concerning, contemporary studies consistently report high rates of stress urinary incontinence after this operation.1-5 The latest of the above-referenced studies was authored by Dr Voelzke and colleagues from 10 institutions describing outcomes of the largest to date patient cohort of 137 patients at a mean followup of 32.3 mo (12-118) and incontinence rates of 32% (ranging 18%-70% between centers).5 Remarkably, a significant proportion of patients required additional auxiliary maneuvers to complete anastomoses, including corporal splitting (71.5%), partial pubectomy (12.4%), partial prostatectomy (37.2%), gracilis flap (23.4%), and abdominal counter-incision (5.6%). Who would consider a urethroplasty that requires such aggressive, tedious, and often challenging maneuvers as “minimally invasive”?
Further, Chung and associates demonstrated that when this operation is applied as the first-line therapy for a stenotic, but not disrupted, bulbomembranous/sphincteric urethra in patients after radiation, it unsurprisingly produces higher rates of incontinence than in patients with pelvic fracture-associated urethral injuries (33% vs 12%).6
Let’s examine the data that demonstrate clearly why nontransecting approaches to posterior urethral stenosis are a preferred approach in a challenging patient population. Employing either a Kulkarni one-sided dissection or ventral approach, one can preserve the bulbar blood supply (at least unilaterally if not bilaterally), avoid circumferential urethral dissection (including near the rectum), avoid excision of the sphincter, and eliminate the reliance on radiated and vascularly compromised ends to heal properly. Currently only a few studies exist demonstrating benefits of a nontransecting buccal mucosa graft (BMG) augmentation techniques in patients with postradiation posterior stenosis. Ahai et al published single-center outcomes of ventral BMG for radiated strictures on 36 patients with a success rate of 71% at 26 months and demonstrating lower rates of de-novo SUI at 10.5%.7
Policastro and colleagues reported on a multicenter cohort of 79 patients with posterior stenosis after radiation therapy uniformly treated with dorsal onlay BMG placed through a one-sided approach (Kulkarni-type dissection) (see Figure).8,9 In this cohort, no additional auxiliary maneuvers were used (no gracilis flap, pubectomy, corporal splitting, or abdominal counter-incision). A majority of patients (65%) returned home on the same day after the operation or after a 23-hour stay. At a mean follow up of 29.6 months (12-88), recurrence-free rate was 82.3% and the rate of de novo stress urinary incontinence (SUI) was only 8%.
Additionally, regardless of the rates of de novo SUI, a significant proportion of patients in all postradiation stenosis series are reported to have persistent SUI and require subsequent artificial urinary sphincter (AUS) placement. It has been hypothesized that choosing transecting urethroplasty may compromise the future longevity of subsequent AUS. A large multinational study spearheaded by MedStar/Georgetown Medical School and presented at AUA2023 by Davis and associates demonstrated dismal outcomes in patients with prior transecting urethroplasty that undergo subsequent AUS placement. Specifically, the risk of AUS explanation due to erosion/infection/urethral atrophy are higher (53%) than patients who undergo prior nontransecting urethroplasty (29%).10
To summarize, these early findings are promising in several different ways: (1) nontransecting BMG augmentation techniques are feasible in select patients after radiation, with excellent urethral patency rates, (2) BMG can be placed into and survive in a graft bed that may be considered suboptimal, including in patients with prior radiation, (3) dorsal onlay BMG urethroplasty allows avoidance of invasive auxiliary maneuvers, (4) de novo SUI rates are lower compared to historically higher rates observed with excisional (read “sphincter excision”) techniques, and (5) preservation of urethral continuity and urethral vascularity may be important if not for other reasons, at least in the interest of improved longevity of future AUS placement. Given these advantages, I argue that dorsal onlay BMG urethroplasty should be used as a first-choice reconstructive option for patients with prior radiation and associated posterior stenosis. In contrast, EPA has only a limited role in a select population of patients, specifically with less common conditions such as complete lumen obliteration, vesico-urethral anastomotic disruption, or necrotic cavities where excision is mandatory.
- Keith CG, Davenport MT, Kavoussi M, Yi YA, Bergeson RL, Morey AF. Long-term outcomes of anastomotic urethroplasty for radiation-induced strictures. World J Urol. 2020;38(12):3055-3060.
- Meeks JJ, Brandes SB, Morey AF, et al. Urethroplasty for radiotherapy induced bulbomembranous strictures: a multi-institutional experience. J Urol. 2011;185(5):1761-1765.
- Hofer MD, Zhao LC, Morey AF, et al. Outcomes after urethroplasty for radiotherapy induced bulbomembranous urethral stricture disease. J Urol. 2014;191(5):1307-1312.
- Fuchs JS, Hofer MD, Sheth KR, Cordon BH, Scott JM, Morey AF. Improving outcomes of bulbomembranous urethroplasty for radiation-induced urethral strictures in post-Urolume era. Urology. 2017;99:240-245.
- Voelzke BB, Leddy LS, Myers JB, et al. Multi-institutional outcomes and associations after excision and primary anastomosis for radiotherapy-associated bulbomembranous urethral stenoses following prostate cancer treatment. Urology. 2021;152:117-122.
- Chung PH, Esposito P, Wessells H, Voelzke BB. Incidence of stress urinary incontinence after posterior urethroplasty for radiation-induced urethral strictures. Urology. 2018;114:188-192.
- Ahyai SA, Schmid M, Kuhl M, et al. Outcomes of ventral onlay buccal mucosa graft urethroplasty in patients after radiotherapy. J Urol. 2015;194(2):441-446.
- Policastro CG, Simhan J, Martins FE, et al. A multi-institutional critical assessment of dorsal onlay urethroplasty for post-radiation urethral stenosis. World J Urol. 2021;39(7):2669-2675.
- Blakely S, Caza T, Landas S, Nikolavsky D. Dorsal onlay urethroplasty for membranous urethral strictures: urinary and erectile functional outcomes. J Urol. 2016;195(5):1501-1507.
- Davis M, Hays E, Kolyvas P, et al. Pd35-02 Retrospective multicenter analysis of long-term outcomes after artificial urinary sphincter following urethroplasty. J Urol. 2023;209(Supplement 4):e974.