Comparison of 120–200 W 2 μm Thulium:Yttrium-Aluminum-Garnet Vapoenucleation of the Prostate

Abstract

Purpose:

To evaluate efficacy and safety of 200 W 2 μm thulium:yttrium-aluminum-garnet vapoenucleation of the prostate (ThuVEP) for patients with benign prostatic obstruction (BPO).

Patients and Methods:

Twenty-eight consecutive patients with symptomatic BPO were treated with 200 W ThuVEP. Patients were matched for age and preoperative prostate volume with 28 patients from our 120 W ThuVEP database. Patient data and postoperative outcome at 12-month follow-up were compared.

Results:

Mean prostate volume (65.39 vs 68.62 cc) and resected weight (40.72 vs 53.18 g) differed not significantly between 200 and 120 W ThuVEP. The percentage of resected tissue was lower with 200 W compared with 120 W (58.48 vs 72.93%, P=0.047) because of the higher rate of ablated tissue. There were no differences in mean operative (69.21 vs 78.67 min), laser (45.43 vs 48.58 min), morcellation (16.52 vs 20.48 min), and catheter (2.2 vs 2.1 d) time between the devices. Three patients needed immediate re-treatment (hemorrhage necessitating coagulation 1=200 W, secondary apical resection 2 120/200 W). One (1.79%) patient (120 W) needed a blood transfusion postoperatively. Fifty-one (91%) patients completed 12-month follow-up. Quality of life, International Prostate Symptom Score, peak urinary flow rate, postvoid residual urine, prostate-specific antigen level, and prostate volume improved significantly (P≤0.019) and were not different between the devices. At follow-up, two (3.57%) patients (120/200 W) had a bladder neck contracture.

Conclusions:

ThuVEP is a safe and efficacious procedure for patients with symptomatic BPO. 120 and 200 W ThuVEP had an equivalent clinical outcome at 12-month follow-up.

Introduction

T ransurethral resection of the prostate (TURP) is still considered the gold standard for the treatment of patients with benign prostatic obstruction (BPO).¹ Because patients who are undergoing treatment for BPO are progressively older with more comorbidities, the need for more minimally invasive surgical techniques is constantly growing to offer treatment to every prostate size.² Various laser devices have been introduced to decrease morbidity and to achieve comparable surgical outcome. Holmium laser enucleation of the prostate (HoLEP) has been proven as a size independent method for the management of BPO with excellent long-term results in terms of reoperation and complication rates.^3
–5 Alternatively, 70 W thulium:yttrium-aluminum-garnet (Tm:YAG) vapoenucleation of the prostate (ThuVEP) has been introduced showing promising results as a size independent method for the management of BPO.^6,7 The 200 W Tm:YAG laser device has been introduced recently into clinical practice. Consequences for ThuVEP using the 200 W Tm:YAG device have not been determined so far.

The aim of this prospective study was, therefore, to compare surgical efficacy and safety of 200 and 120 W ThuVEP in patients with symptomatic BPO and to provide 12-month follow-up.

Patients and Methods

This is a prospective analysis of 28 consecutive patients who presented with symptomatic BPO and underwent 200 W ThuVEP between November and December 2009 at our institution. Patients were matched for age and preoperative prostate volume with 28 patients from our 120 W ThuVEP database.

Exclusion criteria were maximum urinary flow rate (Qmax) >15 mL/s, International Prostate Symptom Score (IPSS) <7 points, urodynamically diagnosed neurogenic bladder, prostate cancer, previous prostatic or urethral surgery. Preoperative assessment included prostate volume by transrectal ultrasonography (TRUS), postvoid residual (PVR) urine by abdominal ultrasonography, digital rectal examination (DRE), IPSS, quality of life (QoL), prostate-specfic antigen (PSA) assay, urine analysis, and urine culture. Uroflowmetry was performed in all patients except those in urinary retention. In patients with suspect age-specific PSA values or suspect DRE, a 12-core needle biopsy of the prostate was performed.

ThuVEP was performed by two experienced surgeons to minimize effects of the learning curve on surgical outcome. ThuVEP was performed using the 120 or 200 W 2 μm continuous wave Tm:YAG laser (RevoLix,^® LISA laser products, Katlenburg, Germany) as the energy source. Laser energy was delivered through a 550 or 800 μm optical core bare-ended, reusable laser fiber (RigiFib,^® LISA laser products, Katlenburg, Germany). The procedure was performed using a 26F continuous-flow laser resectoscope in combination with a mechanical tissue morcellator (Piranha^® TUR-Set, Richard Wolf, Knittlingen, Germany). All interventions were performed using physiologic saline as irrigation fluid. Spinal anesthesia was performed in most patients, except in those with decline of spinal anesthesia, coagulopathy, and failed regional anesthesia, in whom general anesthesia was used.

The technique of ThuVEP has been reported in detail.⁶ The catheter was removed routinely 48 hours after ThuVEP. Patients were discharged after removing the catheter and when the patients were able to void adequately.

Blood loss was estimated by comparing the hemoglobin value 1 day before surgery with the corresponding value on the first postoperative day. Enucleated tissue was histopathologically analyzed in all patients. Patients were invited for a 12-month follow-up visit after surgery and examined with TRUS; PSA, Qmax, PVR, IPSS, and QoL were evaluated. If they had not responded to mailed invitations, a structured telephone interview was performed. Patients were asked for nonresponding, potential complications, and operative interventions.

Statistical analysis was performed using the calculating program Statistical Package for Social Sciences (SPSS, Inc., Chicago, IL, version 11.5.1) for Windows. Patient data were expressed as mean±standard deviation or as median with interquartile range. Differences between 120 and 200 W ThuVEP were assessed using the Mann-Whitney U test, while improvement in the assessed parameters in each group was calculated using the t test. Categorial variables were compared using the chi-square-test. P<0.05 was considered statistically significant.

Results

A matched cohort of 56 patients who underwent 200 W (n=28) or 120 W (n=28) ThuVEP were compared. Table 1 lists baseline characteristics of both groups. Thirty (53.6%) patients had a prostate volume >50 cc, with 19 (34%) and 14 (25%) having glands of ≥80 and ≥100 cc, respectively. The American Society of Anesthesiologists score was significantly higher in the 120 W ThuVEP (2.43±.57 vs 2.1±0.57; P=0.039) compared with the 200 W ThuVEP. Table 2 lists perioperative data. The percentage of resected tissue (72.93±24.72 vs 58.48±32.3%, P=0.047) was significantly higher with 120 W ThuVEP compared with 200 W ThuVEP.

Table 1.

Baseline Characteristics

	200 watt ThuVEP	120 watt ThuVEP	P value
No. of patients (n)	28	28
Age (years)	70.18±8.39 (53–90)	68.46±7.29 (49–87)	0.549
PSA (ng/mL)	8.67±11.21 (0.28–48)	3.82±3.29 (0.38–15)	0.109
Prostate volume (cc)	65.39±39.15 (20–170)	68.62±38.75 (20–160)	0.724
IPSS	23.00±6.69 (8–35)	21.16±7.78 (8–35)	0.439
QoL	4.47±0.98 (2–6)	4.48±1.29 (1–6)	0.687
Qmax (mL/s)^a	7.92±2.7 (4.8–13.6)	10.24±3.89 (3.6–15)	0.145
PVR (mL)^a	89.45±49.67 (14–150)	138.47±107.22 (5–530)	0.112
ASA score	2.1±0.57 (1–3)	2.43±0.57 (1–3)	0.039
Patients with preoperative urinary retention (%)	13 (46.42%)	7 (25%)	0.096
Mean episodes of urinary retention	1.38±0.65 (1–3)	1.71±1.5 (1–5)	1.000

Data indicated as mean values±standard deviation (range).

Except those in urinary retention.

ThuVEP=Thulium:yttrium-aluminum-garnet vapoenucleation of the prostate; PSA=prostate–specific antigen; IPSS=International Prostate Symptom Score; QoL=quality of life; Qmax=maximum urinary flow rate; PVR=postvoiding residual; ASA=American Society of Anesthesiologists.

Table 2.

Operative Data

	200 watt ThuVEP	120 watt ThuVEP	P value
No. of patients (n)	28	28
Laser energy (kJ)	234.85±124.23 (70.39–470.62)	176.52±82.52 (11.99–392.32)	0.091
Laser energy/laser activation time (kJ/min)	10.65±2.00 (6.07–12.40)	6.87±0.96 (4.16–7.4)	0.000
Total operative time (min)	69.21±39.8 (20–210)	78.67±29.64 (34–153)	0.127
Laser activation time (min)	22.43±13.74 (7–58)	24.55±7.67 (16–36)	0.233
Total laser time (min)	45.43±34.05 (10–165)	48.58±21.06 (23–93)	0.182
Morcellation time (min)	16.52±7.69 (4–35)	20.48±17.27 (4–80)	0.958
Morcellation efficiency (g/min)	2.84±1.88 (0.67–8.75)	2.97±1.34 (0.5–5.75)	0.470
Enucleation efficiency (weight/total laser time) (g/min)	1.06±0.74 (0.13–2.33)	1.26±0.94 (0.09–3.88)	0.734
Operation efficiency (weight/total operative time) (g/min)	0.59±0.37 (0.11–1.33)	0.68±0.37 (0.07–1.70)	0.360
Resected weight (g)	40.72±29.63 (5–112)	53.18±39.47 (5–170)	0.293
Percentage resected tissue (%)	58.48±32.3 (23–140)	72.93±24.72 (21–132)	0.047
Hemoglobin decrease (g/dL)	1.17±1.02 (–0.5–3.8)	1.47±0.89 (–0.1–3.1)	0.153
Catheter time (d)	2.21±0.69 (2–5)	2.1±0.42 (2–4)	0.619

Data indicated as mean values±standard deviation (range).

Fifty-one (91.07%) patients were available for review at the 12-month follow-up mark. One patient died during the follow-up, two refused to come, and one patient moved abroad. In addition, one patient had apolexia and was bedridden and therefore unable for a follow-up visit.

At follow-up, IPSS, QoL, Qmax, PVR, PSA, and prostate volume improved significantly (P≤0.019) and were not different between the devices (Table 3). Median PSA value and prostate volume decrease was 91% (87%) and 85% (85%) with 200 (120) W ThuVEP, respectively.

Table 3.

Baseline and Follow–Up Data

	Baseline	At discharge	12–month follow–up	Baseline vs follow–up P value
No. of patients (n)	56	56	51
No. of patients (n)
120 watt ThuVEP	28	28	25
200 watt ThuVEP	28	28	26
IPSS
120 watt ThuVEP	21.16±7.78 (8–35)	n.a.	4.88±5.25 (0–17)	0.000
200 watt ThuVEP	23.00±6.69 (8–35)	n.a.	4.27±4.26 (0–18)	0.000
P value	0.439		0.169
QoL
120 watt ThuVEP	4.48±1.29 (1–6)	n.a.	1.5±1.37 (0–6)	0.000
200 watt ThuVEP	4.47±0.98 (2–6)	n.a.	1.09±1.04 (0–3)	0.000
P value	0.687		0.300
Qmax (mL/s)
120 watt ThuVEP	7.92±4.61 (4.8–13.6)^a	22.94±7.19 (13.2–33.4)	23.31±8.62 (11.8–46.1)	0.000
200 watt ThuVEP	10.24±3.89 (3.6–15)^a	22.01±8.07 (13.4–37.9)	27.05±10.21 (12.6–49.3)	0.000
P value	0.145	0.779	0.185
PVR (mL)
120 watt ThuVEP	138.47±107.22 (5–530)^a	15.89±25.42 (0–100)	21.75±30.92 (0–117)	0.001
200 watt ThuVEP	89.45±49.67 (14–150)^a	20.25±24.84 (0–80)	20.90±21.14 (0–70)	0.001
P value	0.112	0.348	0.609
Prostate volume (cc)
120 watt ThuVEP	68.62±38.75 (20–160)	n.a.	10.52±5.30 (4.4–24)	0.000
200 watt ThuVEP	65.39±39.15 (20–170)	n.a.	9.76±10.35 (1.5–38)	0.001
P value	0.724		0.171
PSA (ng/mL)
120 watt ThuVEP	3.83±3.29 (0.38–15)	n.a.	0.54±0.34 (0.09–1.29)	0.000
200 watt ThuVEP	8.67±11.21 (0.28–48)	n.a.	0.45±0.27 (0.1–0.87)	0.019
P value	0.109		0.865
PSA reduction (%)	–
120 watt ThuVEP		n.a.	83±13 (39–95)
		n.a.	87 (79; 91)
200 watt ThuVEP			85±17 (52–1)
			91 (77.5; 96)
P value			0.217
TRUS reduction (%)	–
120 watt ThuVEP		n.a.	83±8 (67–96)
		n.a.	85 (77; 89)
200 watt ThuVEP			84±14 (5–99)
			85 (75; 94)
P value			0.631

Data indicated as mean values±standard deviation (range) and/or median (interquartile range).

Except those in urinary retention.

THuVEP=thulium:yttrium-aluminum-garnet vapoenucleation of the prostate; IPSS=International Prostate Symptom Score; n.a.=not analyzed; QoL=quality of life; Qmax=maximum urinary flow rate; PVR=postvoid residual; PSA=prostate–specific antigen; TRUS=transrectal ultrasonography.

Table 4 lists adverse events. Regarding the occurence of adverse events, there were no differences between 120 and 200 W ThuVEP. None of the patients in the 200 W group received blood transfusions, whereas one (1.79%) with 120 W ThuVEP did. While 14.29% of the patients who were treated with the 200 W device had transient irritative urinary symptoms, 10.71% of the patients who were treated with 120 Watt ThuVEP did. Transient urge incontinence occurred in one (3.57%) patient after 200 Watt ThuVEP and in three (10.71%) patients after 120 W ThuVEP, whereas transient stress incontinence was observed in seven (25%) patients after 200 W ThuVEP and three (10.71%) patients after 120 W ThuVEP.

Table 4.

Complications After Thulium:Yttrium-Aluminum-Garnet Vapoenucleation of the Prostate with Mechanical Morcellation

	200 watt ThuVEP	120 watt ThuVEP	n (%)	P value
No. of patients (n)	28	28	56
Early complications
Blood transfusions (n)	–	1 (3.57%)	1 (1.79%)	0.274
TURS (n)	–	–	–
Transient irritative urinary symptoms (n)	4 (14.29%)	3 (10.71%)	7 (12.5%)	0.454
Transient urge incontinence (n)	1 (3.57%)	3 (10.71%)	4 (7.14%)	0.265
Transient stress incontinence (n)	7 (25%)	3 (10.71%)	10	0.158
	Grade I 4	Grade I 3	(17.86%)
	Grade II 2
	Grade III 1
Recatheterization (n)	3 (10.71%)	–	3 (5.36%)	0.077
Reoperation^a
Hemorrhage necessitating coagulation (reoperation) (n)	1 (3.57%)	–	1 (1.79%)	0.274
Residual adenoma at the apex of prostate fossa (n)	1 (3.57%)	1 (3.57%)	2 (3.57%)	0.5
Clot retention (n)	–	–	–	–
Injury of the bladder wall during morcellation (n)	1 (3.57%)	–	1 (1.79%)	0.274
Incomplete morcellation (n)	–	–	–	–
Overall immediate reoperation rate (n)	2 (7.14%)	1 (3.57%)	3 (5.36%)	0.265
Late complications at follow-up
Cumulative incidence of UTI during follow-up (n)	4 (14.29%)	3 (10.71%)	7 (12.5%)	0.454
Epididymitis (n)	–	2 (7.14%)	2 (3.57%)	0.147
Persistent irritative urinary symptoms (n)	–	1 (3.57%)	1 (1.79%)	0.274
Persistent urge incontinence (n)	–	–	–	–
Persistent stress incontinence (n)	–	1 (3.57%, Grade I)	1 (1.79%)	0.274
Bladder neck contracture (reoperation) (n)	1 (3.57%)^b	1 (3.57%)	2 (3.57%)	0.5
Submeatal/meatal stenosis (n)	–	–	–
Urethral stricture (reoperation) (n)	1 (3.57%)^b	–	1 (1.79%)	0.274
Cumulative reoperation rate	1 (3.57%)	1 (3.57%)	2 (3.57%)	0.5

Multiple nominations possible; ^bsame patient.

ThuVEP=thulium:yttrium-aluminum-garnet vapoenucleation of the prostate; TURS=transurethral resection syndrome; UTI, urinary tract infection.

Complete remission of those symptoms was achieved in most patients within 3 months after surgery with conservative treatment. At follow-up, one patient, however, complained of grade 1 stress incontinence (1.79%) and one patient needed anticholinergic treatment (4.76%) because of storage symptoms in the 120 W ThuVEP group, respectively. Immediate recatheterization was necessary in three (10.71%) patients who were treated with 200 W ThuVEP within 1 week after surgery (3.6%) because of residual tissue at the apex of the prostate fossa (1), postoperative swelling (1), and hemorrhage (1). Two of these patients (7.14%) needed reoperation, while reoperation was necessary in one (3.57%) patient in the 120 W ThuVEP group because of residual tissue at the apex of the prostate. Two (3.57%) cases of bladder neck contracture (BNC) were observed during follow-up with one in each laser group. BNC was successfully treated with the 70 W Tm:YAG laser in the technique previously reported.⁸ In one patient treated with the 200 W device, an urethral stricture was incidentally detected in addition to the BNC. Seven (12.5%) patients had urinary tract infections (UTI) during follow-up, and two (3.57%) patients who were treated with the 120 W device had an episode of epididymitis.

Discussion

Various laser devices have been introduced for the management of BPO to decrease morbidity and to achieve comparable surgical outcome as TURP or open prostatectomy (OP). GreenLight laser vaporization and HoLEP have played a prominent role in the past decade.^2,9,10 The latter provides the most effective deobstruction because of complete dissection of the adenoma from the pseudocapsule. Despite excellent long-term results, the steep learning curve restricts the HoLEP technique to few centers worldwide. ThuVEP was currently developed using the same retrograde technique as HoLEP.^6,7,11 Contrary to the pulsed holmium:YAG laser, the energy of the Tm:YAG laser is delivered in a continuous wave mode, which can provide maximum hemostasis and coagulation, to perform a smooth incision or vaporization. The Tm:YAG laser therefore allows an uncomplicated correction of the layer of enucleation during ThuVEP. This may lead to a possible advantage over HoLEP where identification of the tissue layer at the surgical pseudocapsule is mandatory and sometimes challenging. Moreover, residual prostate tissue can be vaporized very easily on the surgical pseudocapsule because of the excellent ablation capacity of the Tm:YAG laser. We found higher tissue vaporization rates with the 120 Watt Tm:YAG device despite comparable bleeding rates and tissue penetration, as with the 70 W device.¹² Consequences for ThuVEP using the newly introduced 200 W Tm:YAG device have neither been clinically nor experimentally defined yet. In theory, the 200 W Tm:YAG device might provide a more effective ThuVEP compared with 70 or 120 W because of higher ablation capacity.

Accordingly, the percentage of resected tissue was higher with 120 W compared with 200 W ThuVEP in this series. The 120 and 200 W ThuVEP were, however, equally effective with regard to enucleation and operation efficiency, although a weak trend to shorter laser and operative time was notable in the 200 W ThuVEP. Thus, the excellent ablation capacity of the 200 W Tm:YAG device might rather offer an advantage over the 120 W device in thulium vaporization of the prostate. The 120 and 200 W ThuVEP showed an equivalent, significant relief of obstructive symptoms in patients with symptomatic BPO. Improvement in voiding parameters (Qmax, PVR) and symptom scores (IPSS, QoL) after ThuVEP is comparable with HoLEP,^13

–16 TURP,^10,14
–16 and OP.^3,13 The PSA value (87/91%) and prostate volume (85%) reduction 1 year after 120/200 W ThuVEP confirms complete removal of the prostatic adenoma, comparable with HoLEP.^5,17
–19

Intraoperative and postoperative complications were low at both levels of laser power and not different between the Tm:YAG devices in our series. Only one (1.79%) patient had a blood transfusion in the immediate postoperative course, in accordance with HoLEP (≤1.9%)^2,9,10,20 and considerably lower than in TURP (3.4%)²¹ or OP (7.5%).²² In our study, immediate recatheterization was necessary in 5.36% of the patients, comparable with HoLEP (0%–17%)^9,13,23 and TURP (0%–13.3%),¹⁰ but higher than in OP (2.9%).²² This is presumably because of postoperative swelling and shorter catheter time in ThuVEP compared with OP. On the other hand, the immediate reoperation rate after ThuVEP was 5.36%, up to 5.4% after HoLEP,^2,9,10,13 up to 14.3% after TURP,¹⁰ and 3.7% after OP,²² respectively.

Early postoperative stress incontinence (17.86%) after ThuVEP was markedly elevated in our series. One (1.79%) patient, however, had grade 1 incontinence at 1-year follow-up, while the other patients were continent after conservative treatment within 3 months postoperatively. At 12-month follow-up, stress incontinence rates were ranging from 0% to 3.3% for HoLEP,^{5,14
–16,20,24} 0% to 2.2% for TURP,^1,14,15 and 0.5% for OP,²⁵ respectively. Transient irritative urinary symptoms were a complaint in 12.5% and urge incontinence 7.14% of the patients after ThuVEP in this series. Urge incontinence occurred in the immediate postoperative course in up to 44% of the patients after HoLEP,^{2,9,10,13,14,23,24} 38.6% after TURP,^10,14 and 38.6% after OP,^13,25 respectively. It was suggested, that urge is caused by the high laser energy applied to the pseudocapsule of the prostate.¹³ This would not, however, explain why there were no differences in the occurrence of urge (incontinence) between 120 and 200 W in our series. Complete remission of those symptoms was achieved in most patients within 6 weeks after surgery. The rate of urge incontinence decreased to 0% at 12-month follow-up in our series, comparable with HoLEP,^14,23,24 TURP,¹⁴ and OP.²⁵

Since the retrograde HoLEP technique with mechanical morcellation has been introduced, there are new potential complications such as superficial bladder injury from morcellation (0.5%–18.2%) and superficial ureteral orifice injury (1%–2.1%).^9,23,24 In our series, an injury of the bladder wall occurred in one (1.79%) patient during morcellation, which necessitated no additional therapy. Other complications did not occur, presumably because of completed learning curves of the surgeons in this series.²⁴

The cumulative rate of UTI at follow-up was 12.5% in our series, comparable with HoLEP, TURP, and OP ranging from 0% to 6%,^10,19,23 0% to 22%,¹⁰ and 5.16% to 12.9%,^22,25 respectively. One reason for the high incidence of UTI in our study might be that one third of the patients were in urinary retention before surgery and antibiotic prophylaxis was not administered routinely during hospital stay in patients with negative urine testing.

At 12-month follow-up, the reoperation rate after ThuVEP was 3.57% and equivalent to the BNC rate, comparable with HoLEP,^2,9,10 TURP,^1,10,26 and OP.^3,13,26 None of the patients after 120 and 200 W ThuVEP needed a reintervention because of BPO during follow-up.

These promising preliminary results, however, have limitations because of the retrospective nonrandomized nature of the study and its sample size. In this series, any complication that occurs might lead to a relatively high increase in the complication rate because of the small cohort. On the other hand, PSA value and prostate volume measurement at 1 year follow-up, as surrogates for the amount of tissue enucleated, confirm complete removal of prostatic adenoma. These results should, therefore, be confirmed with larger prospective randomized trials comparing ThuVEP with HoLEP, TURP, or OP. In addition, durability of the ThuVEP procedure should be proven with longer follow-up.

Conclusions

ThuVEP is safe and efficacious for patients with symptomatic BPO. The 120 and 200 W ThuVEP had an equivalent clinical outcome at 12-month follow-up. The 200 W Tm:YAG laser might lead to higher tissue ablation during ThuVEP than the 120 W device. It must be stressed, however, that these initial data represent a small nonrandomized cohort. The results have to be confirmed by a larger series with longer follow-up.

Footnotes

Disclosure Statement

No competing financial interests exist.

Abbreviations Used

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