Prophylactic Urethral Stenting With Memokath After Prostate Implantation for Prostate Adenocarcinoma

• Morbidities assessed on RTOG Morbidity Scale weekly for 12 weeks after PI then biweekly for next 12 weeks
  
• Clinic visits at 2 weeks, 3 months and 6 months; physical exam to include urine flow rate, post-void residual and urinalysis
  
• CT at 1 month post-brachytherapy
  
• Device removal at 6 months (earlier if adverse event or patient wishes to discontinue trial)
  
• Cystoscopy to assess urethra after stent removal
  

• AUA score to assess severity of urinary symptoms
  

Image-guided transperineal permanent prostate brachytherapy (PI) is an accepted curative treatment option for patients with early stage prostate cancer. Multiple reports have defined its efficacy and shown it to be superior to antecedent trans-abdominal techniques. In addition, the efficacy of PI has been shown to be similar to radical retropubic prostatectomy (RRP) and external beam radiotherapy (EBRT). These positive results, however, are gained at the expense of toxicity. The most notable toxicity is associated with the urinary system. The most severe side effect of PI is urinary retention requiring intermittent self-catheterization (ISC).

The reported rate of severe urinary retention following PI is ~10%. Most of these patients can be managed with ISC and alpha-blockers for a few weeks. Although this is generally a temporary phenomenon, a small percentage will eventually require surgical intervention to permit urinary flow. This is a major concern for patients undergoing PI, but should not be a reason to avoid this form of curative treatment.

The use of implantable stents has been successful in BPH. The Memokath® device has been shown to decrease the International Prostate Symptom Score from a mean of 20.3 to 8.2 in the first 3 months after stent placement in patients with bladder outlet obstruction unable to undergo TURP. Few experience side-effects with pain in 3%, hematuria in 3%, incontinence in 6%, and infection in 6%. A multicenter randomized control trial is currently underway assessing the use of this device in patients with recurrent urethral strictures.

Urethral stents have been used with some success in patients with post-brachytherapy bladder outlet obstruction. Five patients, who could not tolerate alpha-blockers or clean intermittent catheterization, received UroLume urethral stents following one or more episodes of urinary retention. All patients were able to void immediately after stent placement. No patients developed incontinence after the stent placement. The main complaints following UroLume® stent placement were urethral bleeding, referred pain at the head of the penis, and dysuria. These symptoms required stent removal in 2 out of the 5 patients. In another study, five patients received SpannerTM urethral stents following significant urinary symptoms after prostate brachytherapy. All patients were able to void spontaneously with no post-void residual volume of urine. Flow rates increased and the International Prostate Symptom Score decreased from a mean of 25.2 to 10 (p=0.03). However, two patients experienced pain, which required removal of the stent.

Given that few patients have experienced side effects with the Memokath® urethral stent in bladder outlet obstruction, we wish to assess the toxicity associated with this stent in a post-brachytherapy setting. In addition, we would like to assess its efficacy when used prophylactically in reducing bladder outlet obstruction following prostate brachytherapy and its impact on the AUA score.