Transurethral Needle Ablation of the prostate (TUNA): clinical results and ultrasound, endoscopic, and histologic findings in pilot study of patients in urinary retention

Canine prostate models in preclinical studies of minimally invasive interventions: part II, benign prostatic hyperplasia models

Canine prostate is widely used as animal model in the preclinical evaluation of emerging therapeutic interventions. Spontaneous benign prostatic hyperplasia (BPH) is common in adult intact male dogs with two distinct pathological types: glandular and complex form of prostatic hyperplasia. The complex form of prostatic hyperplasia, usually occurring in older dogs, represents an ideal model because of its unique pathologic feature, including not only glandular hyperplasia but also an increase in prostate stromal components. The limited commercial availability of adult dogs with spontaneous BPH motivates experimentally induced BPH in young dogs. Hormone-induced canine BPH model has been well established with various hormonal treatment regimens and administration approaches. The goal of this review is to provide the veterinary background in spontaneous BPH in dogs, summarize the techniques in hormonal induction of canine BPH, and highlight the pathological and clinical limitations of the canine models that may lead to distinct therapeutic responses compared to clinical trials in humans.

Histotripsy of the Prostate in a Canine Model: Characterization of Post-Therapy Inflammation and Fibrosis

INTRODUCTION

Histotripsy is a nonthermal, noninvasive, pulsed ultrasound technology that homogenizes tissue within the targeted volume. From previous experiments, it appeared that the resultant fibrotic response from histotripsy was limited compared with the typical tissue response seen after thermoablation. The objective of this study was to characterize the inflammatory response and quantify patterns of collagen deposition 6 weeks after in vivo canine prostate histotripsy.

METHODS

Histotripsy was applied to the left half of eight canine prostates to produce an intraparenchymal zone of tissue homogenization. Six weeks after treatment, prostates were harvested, sectioned, and stained with hematoxylin and eosin for histologic evaluation, CD3, CD20, and Mac387 immunohistochemistry to characterize the inflammatory components, and picrosirius red staining to identify collagen.

RESULTS

Seven of eight treated prostates exhibited only minimal residual inflammation. Visual microscopic analysis of picrosirius red slides revealed a band of dense collagen (0.5 mm wide) immediately adjacent to the cavity produced by histotripsy. This was surrounded by a second band (1 mm wide) of less dense collagen interspersed among glandular architecture. A lobar distribution of epithelial atrophy and basal cell hyperplasia reminiscent of periurethral glands and ducts was apparent surrounding the margin of the treatment cavities. Tissue loss (-31%) was apparent on the treated side of all prostates while four demonstrated a net decrease in collagen content.

CONCLUSIONS

In vivo histotripsy of canine prostate produced a decrease in prostate volume coupled with a limited inflammatory and fibrotic response. A narrow (1.5 mm) band of fibrosis around the empty, reepithelialized treatment cavity was observed 6 weeks after treatment. In four cases, an overall reduction in collagen content was measured. Further studies are planned to correlate these histologic findings with alteration in mechanical tissue properties and to explore histotripsy strategies for treatment of benign prostatic hyperplasia that optimize tissue volume removal with minimization of fibrosis.

Characterizing TUNA ablative treatments of the prostate for benign hyperplasia with gadolinium-enhanced magnetic resonance imaging

BACKGROUND AND PURPOSE

Transurethral Needle Ablation of the prostate TUNA has been accepted as an office-based treatment for benign prostatic hyperplasia (BPH) for many years. Clinical outcomes have been reported, but the amount and location of the necrosis produced have yet to be characterized. The necrosis caused by TUNA was evaluated by gadolinium-enhanced magnetic resonance imaging (MRI) of the pelvis.

PATIENTS AND METHODS

Twelve patients with BPH/lower urinary-tract symptoms underwent standard TUNA, and MRI scans with gadolinium enhancement were performed before and 1 week after treatment. The images were studied using Analyze software to quantify the amount of necrosis compared with the prostatic volume. Transverse, coronal, and sagittal images were obtained to identify the location of the necrosis.

RESULTS

New gadolinium defects were seen in all patients after TUNA. The lesions coalesced into continuous areas of necrosis and correlated with the site of needle placement. The mean volume of necrosis was 6.84 cc and equated to 8.6% of the prostate volume. No lesions were found near the apex, urethra, or rectum; and none extended beyond the prostate capsule.

CONCLUSIONS

Gadolinium-enhanced MRI demonstrates new vascular defects representing necrosis caused by TUNA of the prostate. This therapy for BPH produces necrotic lesions that can be placed strategically by the surgeon. The standard protocol produces lesions that coalesce to create larger lesions. This MRI study has characterized, for the first time, the heating pattern and intraprostatic necrosis of a complete TUNA procedure.

Transurethral needle ablation of the prostate

PURPOSE OF REVIEW

The review aims at reviewing the evidence published in the peer review literature or otherwise available with particular focus on articles published over the last 2 years on the transurethral needle ablation of the prostate in the treatment of benign prostatic hyperplasia. Prospective noncomparative and comparative studies as well as meta-analyses were considered. Information from the European Real Life database on transurethral needle ablation was also included.

RECENT FINDINGS

The evidence currently available confirms a clinically relevant improvement of lower urinary tract symptoms and quality of life. Impact on voiding dynamics including flow rates, detrusor pressure at maximum flow and postvoid residual, as well on prostate volume, remains marginal.

SUMMARY

All major guidelines in the management of lower urinary tract symptoms in patients with benign prostatic enlargement include transurethral needle ablation of the prostate as a valuable treatment option in patients with severe symptoms and low degree of bladder outlet obstruction, patients at high risk for surgery and patients who wish to avoid surgery or regional/general anaesthesia.

How do I treat and follow my TUNA patients

Transurethral needle ablation (TUNA) of the prostate is an alternative treatment for benign prostatic hyperplasia (BPH) generating temperatures around 100 degrees C leading to necrotic lesions inside the prostate. TUNA is a minimally invasive, low morbidity associated, approach that uses radiofrequency energy. The needles are covered by teflon shields that protect the urethra from thermal injury. Since the introduction of TUNA, there has been a constant upgrading of the device to improve treatment quality. The main advantage of this therapy is the possibility of an outpatient care due to its anaesthesia-free option with a prostatic block. Catheterisation after the procedure is required in 10-40% of cases. Long-term data (5 years) on TUNA demonstrate a sustained improvement of both IPSS score and urinary flow. About a quarter of patients require further intervention at 5 years' follow-up. The safety profile, along with the significant improvement in both objective and subjective parameters observed after TUNA, makes it an attractive approach for symptomatic BPH.

Systematic review and meta-analysis of Transurethral Needle Ablation in symptomatic Benign Prostatic Hyperplasia

BACKGROUND

Benign prostatic hyperplasia (BPH) constitutes a major clinical problem. Minimally invasive therapies for the treatment of symptomatic BPH include Transurethral Needle Ablation (TUNA), but it is unclear what impact this technique has on the disease and its role among other currently available therapeutic options. The objective of this study is to ascertain the efficacy and safety of TUNA in the treatment of BPH.

METHODS

Systematic review of the literature until January 2005 and meta-analysis of clinical studies assessing TUNA in symptomatic BPH. Studies were critically appraised. Estimates of effect were calculated according to the random-effects model.

RESULTS

35 studies (9 comparative, 26 non-comparative) were included. Although evidence was limited by methodological issues, the analysis of relevant outcomes indicates that while TUNA significantly improves BPH parameters with respect to baseline, it does not reach the same level of efficacy as TURP in respect to all subjective and objective variables. Further, its efficacy declines in the long-term with a rate of secondary-treatment significantly higher than of TURP [OR: 7.44 (2.47, 22.43)]. Conversely, TUNA seems to be a relatively safe technique and shows a lower rate of complications than TURP [OR:0.14 (0.05, 0.14)] with differences being particularly noteworthy in terms of postoperative bleeding and sexual disorders. Likewise, TUNA has fewer anesthetic requirements and generates a shorter hospital stay than TURP [WMD: -1.9 days (-2.75, -1.05)]. Scarce data and lack of replication of comparisons hinder the assessment of TUNA vs. other local therapies. No comparisons with medical treatment were found.

CONCLUSION

The body of evidence on which TUNA has been introduced into clinical practice is of only moderate-low quality. Available evidence suggest that TUNA is a relatively effective and safe technique that may eventually prove to have a role in selected patients with symptomatic BPH. TUNA significantly improves BPH parameters with respect to baseline values, but it does not reach the same level of efficacy and long-lasting success as TURP. On the other hand, TUNA seems to be superior to TURP in terms of associated morbidity, anesthetic requirements and length of hospital stay. With respect to the role of TUNA vis-à-vis other minimally invasive therapies, the results of this review indicate that there are insufficient data to define this with any degree of accuracy. Overall cost-effectiveness and the role of TUNA versus medical treatment need further evaluation.

Use and misuse of the concept of quality of life in evaluating surgical treatments for lower urinary tract symptoms

OBJECTIVE

To investigate how quality of life (QoL) components measured by given instruments direct the QoL perspective in treatment studies of lower urinary tract symptoms (LUTS) and benign prostatic hyperplasia (BPH).

METHODS

Computer searches were conducted in Medline, CINAHL and Psychinfo; MeSH terms covering QoL and surgical treatments for BPH and LUTS were combined for the search. The analysis was based on a framework linking components of QoL to patient outcome.

RESULTS

Of the 74 papers meeting the inclusion criteria, 48 were published in 1997-2001, showing the increase of interest of the topic. Most of the papers reported the change in QoL by a one-item scale, whilst only a few reported results from several of the components in the QoL concept. Some papers regarded the change in general health status or parts of health status as changes in QoL. Functional status and symptoms, and the bother of symptoms, were often regarded as indicators of a change in QoL.

CONCLUSION

These analyses show an increasing interest in measuring QoL after surgery for LUTS and BPH. In most of the studies analysed, the batteries of instruments selected were too narrow in scope to study the complexity of QoL. Most papers are based on instruments sensitive to change, but the reports do not distinguish the basic assumptions for understanding relationships important in QoL research and as a result, the reason for change is open to question.

Randomized clinical trial comparing transurethral needle ablation with transurethral resection of the prostate for the treatment of benign prostatic hyperplasia: results at 18 months

PURPOSE

To compare the efficacy and safety of transurethral needle ablation (TUNA) and transurethral resection of the prostate (TURP) for the treatment of benign prostatic hyperplasia (BPH) during an 18-months follow-up.

PATIENTS AND METHODS

A series of 59 patients older than 40 years were included in this study. The entry criteria were prostate size <70 g, maximum urinary flow rate (Q(max)) <15 mL/sec, International Prostate Symptom Score (IPSS) >13, and no suspicion of prostate cancer according to the clinical or laboratory findings. Of the patients, 26 (44%) were treated with TUNA and 33 (56%) with TURP. At 3 and 18 months of follow-up, Q(max), postvoiding residual volume (PVR), IPSS, and the quality of life (QOL) score were compared with the baseline values. The results were also compared in patients undergoing TUNA v TURP.

RESULTS

Improvements in Q(max), PVR, IPSS, and QOL score were statistically significant for both groups at 3 and 18 months of follow-up. The increase in the mean Q(max) of the TURP group was higher than that in the TUNA group, whereas no significant differences were found in the two groups regarding improvements in IPSS and QOL score. There were no complications associated with the TUNA procedure, while 16 retrograde ejaculation, 4 erectile impairment, 2 urethral stenosis, and 1 urinary incontinence cases were observed after TURP.

CONCLUSIONS

The TUNA procedure is an effective and safe minimally invasive treatment with negligible adverse effect for selected patients with symptomatic BPH compared with TURP. It should be considered as an alternative treatment option for younger patients who want to preserve sexual function.

Transurethral prostate ablation using saline-liquid electrode introduced via flexible cystoscope

An interstitial saline-electrode has been developed to couple radiofrequency (RF) energy to prostate tissue in order to produce large lesions quickly and controllably. In this study, we attempted to produce similar results using a flexible catheter introduced transurethrally via a flexible cystoscope. An insulated 4F catheter with an extendable needle electrode (26-gauge, 5-mm exposed metal tip) was introduced through a port of a flexible cystoscope into the urethra of 10 dogs via a small perineal incision (required for the canine U-shaped urethra). Under visual endoscopic guidance, the electrode was placed in the center of the prostate and the needle electrode extended at an angle into the prostate, one lobe at a time. Hypertonic saline (14.6% NaCl) was infused at 2 mL/min through the needle electrode into the tissue for 30 seconds before and during RF application. The energy (50 W, 475 kHz) was delivered for 30, 45, 60, or 90 seconds (RFT System; U.S. Surgical Corporation). Prostate and urethral temperatures were monitored using thermocouples mounted on the catheter. There was an automatic high-temperature shut-off if the urethra reached >42 degrees C or if impedance reached >300 omega during RF energy application. Prostate sizes ranged from 1.4 x 2.0 x 1.4 cm to 5.0 x 4.5 x 4.2 cm. In this group, there were no automatic shut-offs at any of the energy durations, and the lesions produced ranged from 1.3 x 1.3 x 1.1 cm (0.99 cm3) to 1.6 x 2.7 x 2.2 cm (5.03 cm3). The average ablation volumes produced were 1.76 cm3 at 30 seconds' RF application, 2.42 cm3 at 45 seconds, 3.96 cm3 at 60 seconds, and 5.03 cm3 at 90 seconds. Histologic examination revealed typical coagulation necrosis in the treatment zone without tissue desiccation. Introduction of the saline-electrode through a flexible cystoscope provides a minimally invasive procedure that quickly and controllably produces large lesions that may provide effective treatment for benign prostatic hyperplasia with less patient discomfort.

Pilot study of transurethral needle ablation (TUNA) in treatment of nonbacterial prostatitis

Transurethral needle ablation (TUNA) was performed on seven patients with chronic nonbacterial prostatitis who failed to respond to conventional treatments administered for more than half a year. The TUNA procedure heated the prostate to a temperature ranging from 90 degrees to 100 degrees C while the urethral temperature was maintained below 43 degrees C by a protective sheath and irrigation. After treatment, four patients showed complete resolution of symptoms and three a partial improvement. All patients had a decrease in the leukocyte count in expressed prostatic secretions (EPS) 1 month after treatment. Recurrence of abnormal inflammatory cells in the EPS was noted in two patients at 3 months after treatment. The subjective improvement has been maintained during the subsequent follow-up. From these results, TUNA is considered to be an effective, safe, and easy treatment for most patients with nonbacterial prostatitis.

Transurethral prostate ablation with saline electrode allows controlled production of larger lesions than conventional methods

A novel technique for prostate ablation using radiofrequency (RF) energy coupled to tissue with interstitial perfusion of saline solutions from a screw-tip catheter has been developed. The electrolyte spreads the current density away from the metal electrode and increases the effective electrode surface area, allowing more RF power input. This prevents tissue desiccation and impedance rise, resulting in controlled production of large lesions. In this study, we attempted to produce similar results using a straight needle and the saline electrode with a transurethral approach and compared the results with those of the same technique without electrolyte perfusion (conventional RF method). For this study, we designed an insulated 22-gauge needle with thermocouples embedded along its length and a 1-cm exposed tip with a retractable intraluminal thermocouple. This needle was inserted into the urethra of 10 dogs through a small perineal incision. Under transrectal ultrasound guidance, the exposed tip of the needle was placed in the center of each lobe. The intraluminal thermocouple was moved from the exposed tip up to the prostate capsule to monitor temperature. The highest power that could be applied in conventional RF methods without immediate desiccation was determined from preliminary experiments as 10 W. Subsequently, 10 W of RF power (475 kHZ) was delivered in one lobe until either the capsule temperature reached 48 degrees C or high impedance (> 400 omega) occurred. In the other lobe, 50 W of RF energy (475 kHz) and electrolyte perfusion (14.6% NaCl, 1 mL/min) were delivered until the capsule temperature reached 48 degrees C or high impedance occurred. Prostate lobe sizes ranged from 3.93 cm3 to 44.47 cm3 (mean 15.07 cm3). At 10 W without saline perfusion, high impedance from tissue desiccation occurred at 45 +/- 27 seconds, with lesions ranging from 0.06 cm3 to 0.93 cm3 (mean 0.34 cm3). At 50 W with saline perfusion, there was no tissue desiccation or impedance rise. The RF application time averaged 181 +/- 115 seconds until the capsule reached 48 degrees C, resulting in lesions ranging from 2.53 cm3 to 22.88 cm3 (mean 8.54 cm3). This study demonstrates that transurethral ablation of the prostate with a saline electrode allows controlled production of larger lesions than conventional RF methods. This may permit a single RF application in each lobe to produce lesions effective for the treatment of benign prostatic hyperplasia even in large glands.

A study of the efficacy and safety of transurethral needle ablation (TUNA) treatment for benign prostatic hyperplasia

The objective of this early phase III study was to determine the efficacy and safety of transurethral needle ablation (TUNA) in patients presenting in acute urinary retention due to benign prostatic hyperplasia (BPH). Between September 1993 and August 1994, 20 patients of mean age 68.8 years were entered into a two-center study and treated with TUNA after presenting in acute urinary retention and having failed at least one trial of voiding. A mean of 5.4 lesions at shield temperatures of 54.6 degrees C were produced. Patients were reviewed at 1, 3, 6, and 12 months (mean, 6.2 months). In 17 of 20 patients, voiding was reestablished in a mean of 2.6 days. Three patients required TURP for persistent retention, and 2 patients had delayed TURP for bothersome symptoms. Two voiders died later of unrelated causes. Five patients were lost to follow-up at 6 months but were voiding when last reviewed. Symptom scores decreased from a mean of 19.0 (range 4-35) to 8.25 (range 1-20) at 12 months (p = 0.06). Mean peak flow rate was 11.4 ml/sec (range 6.6-16.8) at 12 months (p = 0.001). Mean prostatic volume at baseline was 65.8 cc and decreased to 56 cc at 12 months (p = 0.111). The treatment was well tolerated by all patients, and side effects were mild, including urinary tract infection and epididymo-orchitis. This study demonstrates the safety and effectiveness of TUNA procedure in patients with urinary retention due to benign prostatic hypertrophy.