Comparative Postoperative Outcomes of Rezūm Prostate Ablation in Patients with Large Versus Small Glands

Introduction

Benign prostatic hyperplasia (BPH) refers to prostatic glandular, smooth muscle, and connective tissue proliferation. The condition becomes increasingly common past the age of 40 and reaches up to 80% prevalence at 80 years of age. ¹ In many males, BPH leads to enlargement of the prostate gland causing bothersome lower urinary tract symptoms (LUTS). The prevalence of LUTS secondary to BPH has been shown at over 40% over 60 years of age. ² Bothersome LUTS have a significant impact on quality of life in older men. ³ Initial management of LUTS typically focuses on behavioral and medical approaches; however, when these are ineffective, surgery is the gold standard.

In the subset of patients with prostate glands >80 cc, simple prostatectomy was historically considered the most efficient and durable option for treatment. ⁴ However, simple prostatectomy is typically associated with a longer hospital stay, longer postoperative duration of catheterization, and higher risk of perioperative complication. ⁵ Therefore, multiple studies have explored endoscopic management with bipolar transurethral resection of the prostate (TURP) and holmium laser enucleation of the prostate (HoLEP) and have shown comparable outcomes. ^{6 –10}

These trends toward certain well-studied endoscopic techniques are reflected in the American Urological Association (AUA) national guidelines. However, recommendations for treatments such as photoselective vaporization of the prostate (PVP), prostate urethral lift (Urolift), aquablation, and water vapor thermal therapy (Rezūm) are limited to gland volumes <80 cc. ¹¹ This is due to a lack of efficacy data for these minimally invasive techniques in large glands.

Rezūm technology delivers thermal energy via water vapor, which triggers cell necrosis when applied to prostatic tissue. ¹² The water vapor is delivered in 9-second injection treatments, which are delivered transurethrally, to a maximum of 15 treatments. As a result, the procedure is short and does not need to be performed under anesthesia. In fact, most patients require oral sedation only, whereas some clinicians elect to perform prostatic block and less than 20% require intravenous (IV) sedation. ¹³ In addition to this, studies have shown at least 50% improvement in symptomatology and durable results with <5% retreatment rate at 3 years. ¹⁴ Other benefits of Rezūm include no concern for de novo erectile dysfunction and minimal retrograde ejaculation. ^13,14 Due to these benefits, it is important to assess the suitability of Rezūm treatment in patients who have large prostate glands.

However, in the current literature, the majority of studies exclude those patients with glands >80 cc. Based on this gap in knowledge, we sought to determine the efficacy of Rezūm in men with BPH-related LUTS and gland size >80 cc via a single-institution retrospective review.

Patients and Methods

The Rezum procedure uses convective water vapor to deliver thermal energy to prostatic tissue in 9-second bursts. Patients undergo Rezum treatment in the office with preprocedural oral analgesic and sedative medication. Our typical postprocedure catheterization regimen varied from a minimum of 3 days in patients without retention preoperatively, to a maximum of 4 weeks in those who are catheter dependent preoperatively.

After approval by the institutional review board, we queried our institutional database to identify men who had undergone Rezūm therapy at our institution from July 2017 to April 2019. Relevant clinical demographics as well as preoperative parameters including gland size, AUA symptom score (AUASS), Uroflow values, PSA, number of lateral and median lobe treatments, catheterization dependence preoperatively, and complication rates were recorded. Outcomes assessed included pre- and 3-month postprocedural AUASS, Qmax, and postvoid residual (PVR). Demographics, operative parameters, and outcomes were compared between patients with gland sizes less than 80 g and greater than 80 g.

Standard summary statistics were computed. The Wilcoxon signed-rank test was used to compare continuous variables, and chi-squared or Fischer's exact test was used to compare categorical variables. All statistical analyses were conducted using RStudio 1.2.1335.

Results

Our cohort of patients undergoing Rezūm therapy for symptomatic BPH included 182 patients. A total of 25.8% (47/182) had prostate gland volumes larger than 80 cc (Table 1). The mean volume in this large-gland group was 119 cc, compared with 49 cc in the comparison group. A total of 55.3% (26/47) of the large-gland patients were catheter dependent preoperatively compared with 25.2% (34/135) in the comparison group.

Intraoperative factors included a lateral lobe treatment number of 10.3 in the large-gland group vs 5.5 in the comparison group. As with all Rezūm treatments, the maximum number of treatments possible was 15 for a maximum procedural time of 135 seconds.

Clinical outcomes were comparable between prostate volume groups (Table 2). In glands smaller than 80 g, peak flow improved from 9.2 to 12.9 mL/second (p = 0.001) vs improvement from 7.7 to 12.7 mL/second (p = 0.002) in large glands. In glands smaller than 80 g, the preoperative AUASS was 22.1 compared with 12.1 following surgery (p = 0.0005), whereas in larger glands, the AUASS went from 22 to 13.4 (p = 0.04). PVR decreased from 301 to 157 cc in minutes with glands smaller than 80 g (p < 0.001) vs 305–149 cc in men with large glands (p = 0.05).

Postoperative complications most commonly included urinary tract infection (UTI) seen in 15.6% (21/135) of men with glands smaller than 80 cc vs 8.5% (4/47) in those with large glands (p = 0.33) (Table 3). Five of these patients met the criteria for urosepsis and required inpatient admission for IV antibiotics, but did not require ICU level care. The median time to urosepsis onset was 30 days (interquartile range 26–30). Two patients with large glands (4.3%) required transfusion of red blood cells vs no transfusions needed in patients with small glands. The only Clavien 3 or higher complication was cystoscopic clot evacuation under anesthesia in 3/182 (1.6%) Rezūm patients overall. This was not significantly higher in patients with large gland volume.

A subset analysis was performed in the 59 patients who had preoperative urinary retention requiring either intermittent or indwelling catheterization (Table 4). Within this subset, the mean prostate volume for those with large glands was 118 cc vs 51 cc in the <80 cc group (p < 0.0001). There was no difference in preoperative AUASS. The postoperative catheter-free rate was 83% (20/24) in the large-gland group vs 88% in the <80 cc group, which was not statistically significant. Postoperative PVR was 199 cc in the large-gland group vs 192 cc in the other group (p = 0.89). Postoperative peak flow was also not significantly different based on gland volume at 12.6 cc/second flow in glands >80 cc and 14 cc/second in glands >80 cc.

Discussion

Rezūm water vapor thermal ablation is a minimally invasive treatment for BPH that lasts just over 2 minutes at maximum and can be performed without general anesthesia unlike TURP or PVP. It is also relatively simple to perform compared with the steep learning curve of HoLEP or simple prostatectomy. In our institutional practice, many cases are done without pausing anticoagulation if there is a medically necessary indication. Rezūm treatment has been shown to have effective results on LUTS with a durable response over 3 years. ¹⁴

To the best of our knowledge, this study is the first to examine the clinical outcomes of Rezūm treatment specifically in patients with large prostate glands. Within a single institutional database of Rezūm patients, 47 of 182 patients had glands >80 cc. Mean prostate volume was 119 cc in this cohort and 26/47 (55%) were catheter dependent. After Rezūm, all measures demonstrated statistically significant improvement, including AUASS, peak flow, and PVR. Among patients with large glands, all postoperative measures, including AUASS, peak flow rate, and post-PVR, also achieved statistically significant improvement.

In a subset of patients who were catheter dependent preoperatively, 83% of patients with large prostate glands were catheter free after Rezūm, which was not significantly different from patients with smaller glands. There was also no statistically significant difference seen between catheter-dependent men with larger or smaller glands in terms of postoperative PVR or peak flow.

With regard to complication rate, overall there were 3/182 (1.6%) Clavien III complications. There was no clinically significant difference in complication rate between small and large glands. There were two patients with large glands (4.3%) who required transfusion vs none with small glands. The overall UTI rate was 13.7% while the overall urosepsis rate was 2.7%. The relatively high rate of UTI in our cohort is likely an overrepresentation, due to irritative symptoms leading patients to obtain urinalysis. In the first month after Rezūm, there are inflammation and sloughing of necrotic prostatic tissue, which can cause pyuria and confound results. In the case of the five patients who met criteria for urosepsis and required IV antibiotics, the median time to onset was ∼30 days after the procedure. Eighty percent of these patients were still retaining urine and requiring either self-intermittent catheterization or indwelling catheter at the time they developed urosepsis. This may indicate that catheterization, rather than the procedure itself, is an independent risk factor for this complication.

There are multiple studies exploring outcomes for minimally invasive treatment of large-gland BPH with HoLEP, PVP, and TURP vs simple prostatectomy. Humphreys et al. performed a retrospective review of 507 patients undergoing HoLEP and stratified according to gland size of less than 75 cc, 75–125 cc, and greater than 125 cc. Their study did not show any significant differences in postoperative catheterization or hospital stay between these groups. In 2016, Jones et al. performed a systematic review and meta-analysis of HoLEP compared with simple prostatectomy performed via open, laparoscopic, and robotic approaches. This analysis of 3 randomized trials encompassing 263 patients with mean prostate volume of ∼110 cc showed short operative time and higher tissue retrieval with simple prostatectomy. However, HoLEP was associated with less blood loss, shorter postoperative hospital stay, and catheter duration. Voiding outcomes at 24-month follow-up and rate of adverse events were equivalent between the two techniques.

Our study examined outcomes between patients with greater or less than 80 cc prostate volume undergoing Rezūm for symptomatic BPH. We demonstrated that this was an effective procedure for improving AUASS, peak flow rate, and decreasing PVR with a catheter-free rate approaching 85% even in large glands. Complication rate was equivalent to Rezūm in smaller glands and as with any Rezūm, procedural time is standardized at 135 seconds or less due to the maximum treatment number of 15. Therefore, our data indicate that Rezūm treatment is an effective and well-tolerated treatment for large-gland symptomatic BPH, with minimal learning curve or operator variability.

The limitations of this study are inherent to retrospective review. Certain cases did not include complete data, especially in the case of out-of-state patients who were unable to travel back to our institution for follow-up assessment. The comparison group for this study was a cohort of Rezūm patients with prostate size <80 cc rather than patients undergoing another minimally invasive BPH procedure such as PVP, TURP, or HoLEP. However, Rezūm patients are frequently selected for their increased medical complexity precluding general anesthesia or cessation of anticoagulation, which would make it challenging to assign alternate treatments for study purposes. In addition, this was a small cohort of patients although the mean gland size was well above the minimum criterion at 119 cc. Finally, the short duration of follow-up requires further study to ensure long-term durability of improved outcomes in the large-gland cohort.

Conclusion

This is the first study to describe the use of Rezūm therapy for BPH in large glands >80 cc. In our cohort of 47 men, we demonstrated postoperative improvement in AUASS, peak flow, and PVR with statistically significant improvement in all measures. In a subset of patients who were catheter dependent before surgery, results showed an 83% postoperative catheter-free rate in large glands and no significant difference in clinical outcomes when compared with glands <80 cc.

This indicates that Rezūm could be used as a first-line treatment for patients with large-gland BPH, especially those who are medically complex or unwilling to undergo anesthesia. Further studies are warranted to prospectively validate these data in a larger cohort of patients, to obtain long-term follow up and to perform side-by-side comparison of minimally invasive BPH treatments in large glands.