GreenLight HPS™ 120-W laser vaporization vs transurethral resection of the prostate (<60 mL): a 2-year randomized double-blind prospective urodynamic investigation

Authors


João Antonio Pereira-Correia, Servidores do Estado Hospital – Urology, Rua Sacadura Cabral 178 Saúde 6o. Andar – Secretaria de Urologia Rio de Janeiro, RJ 20221-903, Brazil. e-mail: joaoapc@ig.com.br

Abstract

Study Type – Therapy (RCT)

Level of Evidence 1b

What's known on the subject? and What does the study add?

Photovaporization of the prostate (PVP) is now challenging TURP as the standard treatment for lower LUTS caused by BPH. The learning curve for PVP is short and the main advantages of this method over TURP are a shorter period of hospitalization, a shorter period of postoperative vesical catheterization, lower levels of retrograde ejaculation, rare development of dilutional hyponatraemia syndrome, the lack of a need for postoperative vesical irrigation as a result of extremely low indices of postoperative haematuria, and the lack of a need to suspend anticoagulant medication for the surgery. Traditionally, comparisons of the effectiveness of TURP vs PVP have involved parameters such as peak flow urinary rate and post-void residual urine volume measurements, and have employed questionnaires such as the IPSS and the International Index of Erectile Function instruments. However, studies evaluating detailed urodynamic parameters remain scarce and non-comparative

The present study compared postoperative, medium-term urodynamic parameters among patients receiving TURP and high-power PVP. We consider the present study to be distinctive because it involved a double-blind, detailed functional analysis of the vesical emptying stage over the course of 2 years, and did not simply comprise an evaluation of clinical parameters and uroflowmetrics. We saw a reduction of infravesical obstruction, as shown by the significant reduction of ≥20 cm H2O in the mean micturition pressure for the groups studied, as well as a significant reduction in bladder outlet obstruction index. Thus, the present data show that high-power PVP can achieve and maintain the same results as TURP over a period of 24 months regarding an aspect that is particularly important for maintaining vesical health (i.e. detrusor pressure during the evacuation of the bladder). Such urodynamic data describing the functional outcome of PVP are currently missing from the literature.

OBJECTIVE

  • • To assess the impact of GreenLight HPSTM 120-W (American Medical System Incorporation, Minnetonka, MN, USA) laser photovaporization of the prostate (PVP) compared to transurethral resection of the prostate (TURP) on urodynamic results, voiding function and sexual function.

PATIENTS AND METHODS

  • • In total, 20 men with intermediate/severe lower urinary tract symptoms as a result of benign prostatic hyperplasia (BPH) were randomly selected and equally divided into two groups: TURP and PVP.
  • • Urodynamic evaluation was performed and International Prostate Symptom Score (IPSS), International Index of Erectile Function-5 and International Consultation on Incontinence Questionnaire – Short Form questionnaires were completed.
  • • The results were assessed at 2 years.

RESULTS

  • • Mean IPSS scores were reduced in both groups, although they did not differ between the TURP and PVP groups.
  • • There was no significant change in International Index of Erectile Function-5 scores.
  • • Half of the patients in the PVP group developed urge urinary incontinence with spontaneous resolution.
  • • The urodynamic parameters analyzed showed an improvement for both groups, although the values in the TURP group values were not significantly different from those in the PVP group.

CONCLUSIONS

  • • Bladder storage symptoms may represent a major concern, although they are of limited duration in patients undergoing PVP.
  • • High-power PVP can achieve and maintain the same results as TURP over a period of 24 months.
Abbreviations
BOOI

bladder outlet obstruction index

ICIQ-SF

International Consultation on Incontinence Questionnaire – Short Form

IIEF

International Index of Erectile Function

KTP

potassium-titanyl-phosphate

PdetQmax

detrusor pressure at Qmax

PVP

photovaporization of the prostate

PVR

post-void residual urine volume

Qmax

peak urinary flow rate.

INTRODUCTION

TURP is considered the gold-standard surgical treatment for LUTS stemming from infravesical obstruction caused by BPH. In recent years, other endoscopic techniques with short-term success rates have been developed, although they may not be sustainable over the long term. Laser photovaporization of the prostate (PVP) is one of the few surgical alternatives to TURP yielding good results.

Over the last three decades, various types of lasers have been developed to treat symptomatic benign prostate enlargement [1]. PVP using a potassium-titanyl-phosphate (KTP) laser has proven to be particularly interesting for the management of BPH because it uses its physical properties to apply the ‘photoselective’ method to the prostate. It emits a green-coloured laser at a wavelength of 532 nm and, unlike other types of lasers, has high absorption in prostatic tissue oxyhaemoglobin and low absorption in the irrigation solution used in surgery, which provokes an ideal effect for the photovaporization of the prostate gland [2]. The KTP laser has recently been improved with the use of lithium triborate crystals and an increase in its power to 120 W (GreenLight HPSTM 120-W; American Medical System Incorporation, Minnetonka, MN, USA). This gain in power has resulted in an increase in the laser's vaporization speed and effectiveness [3–5].

Traditionally, comparisons of the effectiveness of TURP vs PVP have involved parameters such as peak urinary flow rate (Qmax) and post-void residual urine volume (PVR) measurements. Questionnaires such as the IPSS [6–9] and the International Index of Erectile Function (IIEF) instruments [10] have also been employed. However, studies evaluating detailed urodynamic parameters remain scarce and non-comparative [11,12]. The present study compared postoperative, medium-term urodynamic parameters among patients receiving TURP and high-power PVP.

PATIENTS AND METHODS

Between April and June 2009, 20 men with intermediate/severe LUTS unmanageable by oral pharmacotherapy with α-blockers were prospectively and randomly selected at the outpatient urology clinic of the Servidores do Estado Federal Hospital (Rio de Janeiro, RJ, Brazil). Participants were randomly assigned in accordance with simple randomization procedures (i.e. computerized random numbers) to one of two treatment groups. Among this group, 10 patients underwent TURP and 10 underwent PVP with a high-power (120 W) KTP laser (GreenLight HPSTM 120-W). The patients were not told which type of treatment they were receiving. The present study was performed in accordance with the guidelines of the hospital's ethics committee, and all patients provided their written informed consent.

All members of the study group were subjected to a full anamnesis, physical examination, measurement of total PSA levels, prostatic TRUS, urodynamic evaluation, measurement of jejunal glycaemia concentrations and measurement of blood creatinine concentrations. Drugs that were being used to manage LUTS were suspended for 90 days before operation.

Patients were excluded if they had a total blood PSA level >4.0 ng/dL, a jejunal glycaemia concentration >99 mg/dL a blood creatinine concentration higher than 1.2 mg/dL, a prostate volume >60 mL, suspected malignant neoplasia upon rectal examination, suspicion or presentation of central or peripheral neuropathies, diabetes mellitus, urinary retention, renal dysfunction, urodynamic changes consistent with urethropathy or detrusor hypocontractility, previous pelvic surgeries, dysuria, pain during urination, a history of pelvic radiotherapy or a pre-eminent median lobe shown during TRUS. A urodynamic evaluation was performed before surgery and all of the patients completed the IPSS questionnaire, the five-item version of the IIEF (IIEF-5) and the International Consultation on Incontinence Questionnaire – Short Form (ICIQ-SF), all of which were validated for Portuguese.

SURGICAL TECHNIQUE

The PVP and TURP treatments were performed by one experienced urologist and carried out under spinal anaesthesia as well as i.v. sedation of the patients.

For PVP, a 120-W KTP laser generator (American Medical System Incorporation) was used. Application was performed with a 24-F laser cystoscope via a GreenLight HPSTM laser fiber (American Medical System Incorporation). Isotonic saline irrigation liquid was used for PVP.

TURP was performed with a 26-F continuous flow resectoscope and monopolar diathermy. Mannitol/sorbitol solution was used for irrigation.

Vaporization of the prostatic tissue, as well as prostate resection, were performed after urethrocystoscopy and identification of the ureteral orifices. Both PVP and TURP treatments were carried out from basal to apical, first in the area of the bladder neck (i.e. the middle lobe and, subsequently, the side lobes). Inspection of the urethra, prostatic defect and trigone of the bladder was routine after the procedure. A transurethral catheter was positioned after completion of the operation and left in place with bladder continuous irrigation.

FOLLOW-UP AND DATA ANALYSIS

Patients returned for an outpatient review at 1, 3, 6, 9, 12 and 24 months after surgery and completed the IPSS, IIEF-5 and ICIQ-SF questionnaires. A urodynamic evaluation was performed at 6, 12 and 24 months after surgery. Urodynamic investigations and evaluations were performed in accordance with the standards recommended by the International Continence Society [13]. Certain urodynamic parameters were chosen for analysis. We assessed Qmax, PVR using spontaneous uroflowmetry, and Qmax and the detrusor pressure at Qmax (PdetQmax) using pressure-flow studies. From the pressure-flow study, we calculated the bladder outlet obstruction index (BOOI): BOOI = PdetQmax− 2Qmax[14]. The BOOI was classified as <20 (unobstructed) vs ≥20 (equivocal or obstructed. Patients were also classified according to the presence or absence of detrusor overactivity.

There were two urologists who participated in the postoperative outpatient evaluations and a single uroneurologist was responsible for the postoperative urodynamic evaluations. None of these professionals was involved in the selection of the patients, the operations themselves or the immediate postoperative care. During the consultations and urodynamic examinations, they did not have access to the patient files identifying those who had received TURP or PVP, making this a double-blind study. Only a fourth urologist knew the treatment designations. This same urologist was responsible for distributing the patients for outpatient care and urodynamic evaluation during the 2-year follow-up period.

The comparative analysis among groups was conducted using Student's t-test for continuous data and the Mann–Whitney test for categorical data, using the standard significance value of P < 0.01. Statistical analysis was performed using GraphPad Prism, version 5 (GraphPad Software Inc., La Jola, CA, USA). A power analysis of all results was conducted using the G*Power software, version 3.1.3 (University of Düsseldorf, Dusseldorf, Germany).

RESULTS

Demographic and clinical data for both groups, comprising patient age, preoperative total PSA level, prostatic volume, surgical time, need for blood transfusion, laser energy and period of vesical catheterization/hospitalization, are shown in Table 1. Reoperations were not necessary and perforation of the prostatic capsule did not occur in both groups. The transurethral catheter was removed on the day 2 after surgery (48 h after surgery in PVP group, 72 h after surgery in TURP group). Spontaneous micturition could be observed in all cases.

Table 1.  Overall baseline patient characteristics and perioperative/postoperative parameters of PVP-treated and TURP-treated patients
CharacteristicTURP groupPVP group
RangeMeanRangeMean
  1. PVP, photovaporization of the prostate.

Age (years)56–7863.552–7666.4
PSA level (ng/dL)0.89–2.901.691.15–3.92.03
Prostate volume (mL)30–604730–5843.4
Operation time (min)30–904030–10045
Lasing energy (kJ)45–275151
Period of vesical catheterization/hospitalization (h)7248
Blood transfusionNoNo
Bladder irrigationYesNo

The results of the pre- and postoperative IPSS, IIEF-5 and ICIQ-SF questionnaires are summarized in Table 2. Relative to preoperative values, mean postoperative IPSS scores were reduced by 21 points in the TURP group and by 15 points in the PVP group (P < 0.01). The IPSS scores did not differ significantly between the TURP and PVP groups (P= 0.70). There was no significant changes in IIEF-5 scores in either the TURP group or the PVP group when analyzed independently (P= 0.34) or together (P= 0.36).

Table 2.  Range (R) and mean (A) scores of the IPSS, five-item version of the International Index of Erectile Function (IIEF-5) and International Consultation on Incontinence Questionnaire – Short Form (ICIQ-SF) over 2 years
VariableFollow-up (months)
Before surgery13691224
RARARARARARARA
  1. PVP, photovaporization of the prostate.

IPSS              
 TURP15–31251–1254–1261–1264–1261–1251–166
 PVP9–33222–1272–1261–1262–1162–1061–157
IIEF-5              
 TURP22–252322–252322–242322–252322–242322–242322–2423
 PVP22–242322–242222–242322–242322–252322–242322–2522
ICIQ-SF              
 TURP0–80.8000000000000
 PVP0–91.10–113.30–92.80–72.40–1030000

To analyze the ICIQ-SF score, preoperative urinary incontinence was verified in a patient from the TURP group (who experienced urine release when he had finished urinating and was dressed) and in two patients from the PVP group (who both leaked urine before making it to the bathroom). All three of these patients' problems were resolved after their operations when their ICIQ-SF scores were equal to zero. In the PVP group, however, a significant postoperative rate of urinary incontinence was observed compared to the TURP group (P < 0.04). In total, five (50%) patients developed urge urinary incontinence not associated with detrusor hyperactivity in the urodynamic evaluation from the first month after surgery, with spontaneous resolution between 3 and 12 months after PVP.

The urodynamic parameters analyzed showed an improvement for both groups (Table 3). Concerning free uroflowmetry, significant improvements in Qmax and PVR values over the 2-year follow-up period were verified in both the TURP group (P < 0.01) and PVP group (P < 0.01). The two groups did not differ from each other with respect to their Qmax (P= 0.38) and PVR (P= 0.81) values. When evaluating the flow/pressure study of the urodynamic evaluation, a significant improvement in PdetQmax (P < 0.01) and BOOI (P < 0.01) values was found over the 2-year follow-up period for both study groups. The values for PdetQmax (P= 0.68) and BOOI (P= 0.68) in the TURP group were not significantly different from those of the PVP group.

Table 3.  Urodynamic parameters over 2 years
VariableFollow-up (months)
Before surgery61224
RangeMeanRangeMeanRangeMeanRangeMean
  1. BOOI, bladder outlet obstruction index; PdetQmax, detrusor pressure at Qmax; PVP, photovaporization of the prostate; PVR, post-void residual urine volume; Qmax, peak urinary flow rate.

Qmax (mL/s)        
 TURP4–116.410–2615.410–281813–2918.6
 PVP3–181010–2816.712–3822.213–3220.5
PVR (mL)        
 TURP50–3001770–80140–202.50–306
 PVP25–2501500–1030–1020–254
PdetQmax        
 TURP29–14260.418–5634.724–4234.928–5240.7
 PVP21–10773.19–5629.38–4324.29–4827.7
BOOI        
 TURP21–13249.7(−)32–4(−)11.9(−)14–4(−)1.2(−)9–181.1
 PVP27–9460(−)35–22(−)8.7(−)68–4(−)12(−)33–8(−)4.5

Preoperative urodynamic evaluation showed detrusor hyperactivity in only one patient in the TURP group and in four patients in the PVP group. All five patients showed a definitive resolution by the first urodynamic review at month 6 after surgery.

The powers of all results were calculated retrospectively and ranged from 0.12 to 0.54 (mean = 0.26).

DISCUSSION

PVP is now challenging TURP as the standard treatment for LUTS caused by BPH. The learning curve for PVP is short; 15 procedures on smaller (≤50 mL) prostates are usually adequate [15,16]. The main advantages of this method over TURP are a shorter period of hospitalization, a shorter period of postoperative vesical catheterization, lower levels of retrograde ejaculation, rare development of dilutional hyponatraemia syndrome, the lack of a need for postoperative vesical irrigation as a result of extremely low indices of postoperative haematuria, and the lack of a need to suspend anticoagulant medication for surgery [17–24].

Recent medium-term randomized comparative studies have shown similar rates of improvement in IPSS score, Qmax values and PVR values [25,26]. Similarly, in the present study, a mean reduction of at least 15 points in the IPSS score value was observed, even 24 months after the procedure, independent of the method used. In addition, a mean Qmax increase of at least 10 mL/s was verified, as well as a PVR reduction to insignificant levels in both groups within 2 years. There was no difference in the effectiveness of the two methods with respect to these three parameters.

Regarding postoperative erectile dysfunction, the values of the IIEF-5 questionnaire were unchanged between the PVP and TURP groups. Hamann et al.[27] previously compared low-power (80 W) PVP and TURP and reported similar results in a prospective study involving 45 patients who were tracked for 1 year. At present, no study has shown conflicting results regarding any negative effects of PVP on erectile function. These outcomes may be a result of the low depth of laser penetration into the tissue (≈1 mm) associated with the PVP procedure, which reduces the risk of a thermal lesion of the neurovascular bundles [28].

In the analysis of the results of the ICIQ-SF questionnaire carried out in the present study, urinary urgency and incontinence were reported in half of the PVP-treated patients . Unexpectedly, it was found that these troubling vesical storage symptoms were not a result of detrusor hyperactivity. All patients had a spontaneous resolution of irritative LUTS within 1 year of surgery. The few comparative studies of PVP and TURP in the literature show slightly better results. In a recently published medium-term evaluation, postoperative irritative LUTS was observed in 20% of patients who received PVP [25]. Non-comparative studies, however, have shown higher rates, varying between 34% and 93% of patients [27,29]. An explanation for these results may be that the previous studies included ‘dysuria’ as a form of postoperative irritative LUTS [25]. In all these evaluations, vesical storage symptoms were resolved within 4–6 weeks, with anticholinergic therapy being needed in some cases. Consistent with the hypothesis suggesting that the inclusion of postoperative dysuria in the group of patients receiving PVP may explain the high irritative LUTS rates reported in some studies, we also consider that local effects of the laser (photothermal irritation) and prostatic oedema, mainly in the colovesical region, may, in some way, trigger irritative symptoms [6].

Additionally, the correct use of a surgical laser on prostate tissue is fundamental for avoiding postoperative irritative LUTS. Poor technique can cause a variety of postoperative symptoms of varying intensity [30]. Therefore, we carefully monitor prostatic photovaporization with the aim of preventing these symptoms from occurring unexpectedly. We respect the appropriate distance between the fibre and the tissue aiming to avoid thermal diffusion. We scrupulously inspect the flaws in prostate surface, the vesical triangle and the urethra. There were no inadvertent lesions of the vesical trigone in the present study cohort, which can be a cause of irritative urinary symptoms. In addition to the above practices, in the present series of patients, care was taken to always use the same surgeon for the laser and TURP surgeries.

We consider the present study to be distinctive because it involved a double-blind, detailed functional analysis of the vesical emptying stage over the course of 2 years, and did not simply comprise an evaluation of clinical parameters and uroflowmetrics. A reduction of infravesical obstruction was observed, as shown by a significant reduction of ≥20 cm H2O in the mean micturition pressure for the groups studied, as well as a significant reduction in BOOI. Thus, the present data show that high-power PVP can achieve and maintain the same results as TURP over a period of 24 months regarding an aspect that is particularly important for maintaining vesical health (i.e. detrusor pressure during evacuation of the bladder). Such urodynamic data describing the functional outcome of PVP are currently missing from the literature.

Although there was no loss of follow-up during 24 months, one limitation of the present study was the small number of patients analyzed (n= 20), with corresponding low-power results. Nevertheless, we hope that our findings will encourage further detailed analyses of long-term vesical function related to prostatic photovaporization and thus allow a better evaluation of the parity of the PVP method with TURP, which is still considered as the gold standard for LUTS caused by BPH.

CONFLICT OF INTEREST

None declared.

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