Safety and Efficacy of GreenLight XPS Laser Vapoenucleation in Prostates Measuring Over 150 mL

Abstract

Introduction:

The GreenLight™ XPS Laser System (GL-XPS) is a safe and efficacious treatment for lower urinary tract symptoms due to benign prostatic hyperplasia (BPH), but there is limited evidence on its use in prostates over 150 mL. We demonstrate the safety and efficacy of the GL-XPS system using a vapoenucleation technique in prostate glands measuring over 150 mL.

Methods:

We prospectively collected data on all consecutive patients with prostates measuring over 150 mL on transrectal ultrasound treated with the GL-XPS (AMS, Inc., Minnetonka, MN) at a tertiary referral center from September 2011 to October 2015. Data collected include prostate volume, International Prostate Symptom Score (IPSS) and quality of life (QoL) scores, maximum urinary flow rate (Qmax), postvoid residual (PVR), prostate-specific antigen, complications, and reintervention rates.

Results:

Seventy male patients with a median prostate size of 202 mL (range 152–376 mL) were included. There were 41 patients (59%) in preoperative urinary retention with an indwelling catheter preoperatively. Thirty-seven (53%) patients were American Society of Anesthesiologists (ASA) class 2 and 33 (47%) were class 3. Median operative time was 180 minutes, laser time 97 minutes, energy utilization 674 kJ, and energy density 3.3 kJ/mL, with median 3 fibers used per case. Median length of stay and length of catheterization were 1 day. IPSS and QoL scores demonstrated significant improvements from baseline at all endpoints, improving from 16 to 3.5 and from 4 to 1 at 24 months, respectively (p = 0.001). At 12 months, Qmax and PVR improved from 10.1 to 22.4 mL/s (p = 0.043) and from 84 to 31.4 mL (p = 0.015), respectively. Retreatment was required in two patients (2.9%).

Conclusion:

GL-XPS vapoenucleation provided durable subjective and objective improvements in symptoms and voiding parameters, with no serious adverse events in men with prostates >150 mL.

Introduction

Treatment of lower urinary tract symptoms secondary to benign prostatic hyperplasia (BPH) has traditionally been performed using transurethral resection of the prostate (TURP).^1,2 However, TURP is challenging in large prostates, and for men with prostates over 80 to 100 mL, the alternative has traditionally been simple prostatectomy (SP).^1,2 Laser technology has provided minimally invasive alternatives to SP that may be comparable to TURP. Holmium laser enucleation of the prostate (HoLEP) has been utilized in large prostates and has demonstrated durable long-term results, but is a technically demanding procedure with a significant learning curve.^3

–6

Photoselective vaporization of the prostate (PVP) using the GreenLight XPS Laser System (GL-XPS) has emerged as a safe and efficacious alternative to TURP. The GOLIATH trial demonstrated noninferiority of the GL-XPS system to TURP at 12- and 24-month follow-up, as measured by subjective and objective voiding parameters and complication rates.^7,8 However, this study excluded prostates over 100 mL and had an average prostate size of 49 mL. Although the prior 80 and 120 W systems have been shown to be safe and effective in prostates >80,^9,10 >100,¹¹ and >120 mL,¹² some studies have demonstrated inferior outcomes compared with HoLEP or TURP in large prostates.^3,13,14

There is limited evidence to support the use of PVP in large prostates, although early studies suggest that GL-XPS provides size-independent outcomes and is thus a highly safe and efficacious alternative to TURP, HoLEP, or SP regardless of prostate size.¹⁵ We sought to assess the safety and efficacy of the GL-XPS system using a combined vaporization-enucleation (vapoenucleation) technique in prostates over 150 mL.

Materials and Methods

Study population

This IRB-approved study included all consecutive men with a prostate gland measuring over 150 mL on preoperative transrectal ultrasound (TRUS) treated for BPH with the GL-XPS system (AMS, Inc., Minnetonka, MN) at a tertiary referral center from September 2011 to October 2015. Patients with known prostate cancer or previous pelvic radiation were excluded.

Surgical procedure

The technique of vapoenucleation has been previously described.¹⁶ Briefly, this technique consists of creating a midline groove through the median lobe at the 6 o'clock position to the level of the trigone, which is then extended distally toward the verumontanum. A lateral groove is then created between 4 and 5 o'clock at the bladder neck at the lateral margin of the median lobe and extended distally to meet with the distal aspect of the midline groove. The tissue between the two grooves is then vapoenucleated from the distal margin toward the bladder neck. Prostate fragments are detached and pushed into the bladder. The same technique is then performed on the contralateral side, with a lateral groove created between 7 and 8 o'clock. Next, a high lateral groove is created in the lateral lobe at ∼11 o'clock position and the groove extended distally to meet the area of the previously treated median lobe. The same procedure is performed on the contralateral lateral lobe, with a groove at 1 o'clock. After vapoenucleation of both lateral lobes, the anterior prostate and apex are vaporized, and prostate tissue fragments are removed from the bladder using graspers at the end of the case. It should be noted that vapoenucleation utilizes the laser to vaporize rather than morcellate tissue that has been enucleated. More than 50% of tissue is vaporized during the process, and the remaining smaller fragments are manually extracted with evacuators and graspers. This procedure was conducted under general endotracheal anesthesia in all cases. The surgical team ensured proper preoperative lithotomy positioning with well-padded, symmetrically positioned stirrups and ample padding of all relevant pressure points.

Primary outcomes

Efficacy of the procedure was evaluated at 6, 12, and 24 months using International Prostate Symptom Score (IPSS) and quality of life (QoL) scores, maximum urinary flow rate (Qmax), and postvoid residual (PVR). In addition, prostate-specific antigen (PSA) was utilized as a surrogate marker of prostate gland removal.¹⁷ Safety was evaluated through review of any adverse events related to primary treatment. Reintervention rates were defined as patients requiring retreatment or experiencing an adverse event requiring any invasive or surgical intervention.

Assessment

We prospectively collected data on patient demographics and operative parameters, including operative time, laser time, energy use, and number of fibers. Energy density was defined as the quotient of the amount of energy delivered divided by prostate volume from preoperative TRUS.

Statistical analysis

Operative parameters and postoperative outcomes were not normally distributed and are thus presented as median and interquartile range. Comparisons with baseline were made using the Wilcoxon signed-rank test. Two-sided p < 0.05 was considered statistically significant. Statistical analysis was performed using SPSS Version 21 (IBM Corp., Armonk, NY).

Results

A total of 70 male patients were treated with GL-XPS from September 2011 to October 2015. Baseline characteristics are shown in Table 1. Median prostate size was 202 mL (range 152–376 mL). A total of 41 patients (59%) presented in urinary retention and had an indwelling urethral catheter preoperatively. There were 37 patients (53%) deemed American Society of Anesthesiologists (ASA) class 2 and 33 (47%) deemed ASA class 3. Operative parameters are shown in Table 2. Notably, both median hospital stay and length of catheterization were 1 day. Overall, 86% of patients had hospital stay of 1 day (range 1–4 days) and 91% were discharged catheter free (length of catheterization range 1–13 days). Of patients presenting in preoperative urinary retention, 88% were discharged from the hospital catheter free.

Table 1.

Baseline Characteristics

N	70
Mean age (SD)	74 (8.8)
Mean body mass index (kg/m²)	27.3 (4.0)
Preoperative urinary retention+catheter (%)	41 (59%)
Median lobe (%)	70 (100%)
Alpha blocker	44 (63%)
5-ARI	66 (94%)
Warfarin	3 (4%)
Clopidogrel	4 (6%)
ASA class
2	37 (53%)
3	33 (47%)
Median preoperative TRUS volume (mL)	202.0 (67.5)
Median IPSS	16 (15)
Median QoL	4 (3)
Median Qmax (mL/s)	10.1 (7)
Median PVR (mL)	84 (160)
Median PSA (ng/mL)	8.3 (12)

5-ARI = 5-alpha reductase inhibitor; ASA = American Association of Anesthesiologists; IPSS = International Prostate Symptom Score; PVR = postvoid residual; PSA = prostate-specific antigen; QoL = quality of life; Qmax = maximum urinary flow rate; TRUS = transrectal ultrasound.

Table 2.

Operative Parameters (Median, IQR)

Total operative time (minutes)	180 (70)
Laser Time (minutes)	97 (34)
Energy (kJ)	673.7 (289)
Energy density (kJ/mL)	3.3 (1)
No. fibers	3 (2)
Hospital stay (days)	1 (0)
Length of catheterization (days)	1 (0)

Table 3 shows the number of adverse events from surgery according to the Clavien-Dindo grade. The most common complications were Clavien grade I/II, including postoperative hematuria (n = 16, 22.9%), urinary tract infection (UTI) (n = 4, 5.7%), dysuria (n = 5, 7.1%), and incontinence (n = 4, 5.7%). Two patients (2.9%) required retreatment with a second procedure, both at 22 months after their initial operation. Despite the substantial operative time required for prostates of this size, there were no complications related to positioning or operative duration.

Table 3.

Complications by Clavien-Dindo Grade

I/II
Bleeding, hematuria	16 (22.9%)
UTI	4 (5.7%)
Incontinence	4 (5.7%)
Dysuria	5 (7.1%)
IIIa/IIIb
Bladder neck/urethral stricture	0
Refractory urinary retention	2 (2.9%)

UTI = urinary tract infection.

As shown in Table 4, IPSS and QoL scores demonstrated significant improvements at 6, 12, and 24 months postoperatively. IPSS and QoL scores improved from 16 to 3.5 and from 4 to 1, respectively (p = 0.001). Qmax and PVR, measured at 6 and 12 months postoperatively, were also significantly improved. At 12 months, Qmax and PVR improved from 10.1 to 22.4 mL/s (p = 0.043) and from 84.0 to 31.4 mL (p = 0.015), respectively, and PVR at 24 months was 23.25 mL (p = 0.055). PSA also demonstrated significant reductions at all endpoints, with a sustained reduction from 8.3 ng/mL at baseline to 3.0 ng/mL at 24 months (p = 0.002). Figure 1 demonstrates the significant improvements in all outcomes measured.

FIG. 1.

IPSS (A), QoL (B), Qmax (C), PVR (D), and PSA (E) at baseline, 6-, 12-, and 24-month follow-up. *Statistically significant improvement from baseline, p < 0.05. IPSS = International Prostate Symptom Score; PSA = prostate-specific antigen; PVR = postvoid residual.

Table 4.

IPSS, QoL, Qmax, PVR, and PSA at Baseline and at 6, 12, and 24 Months

	IPSS		QoL		Qmax		PVR		PSA
	Median (IQR)	p-value	Median (IQR)	p-value	Median (IQR)	p-value	Median (IQR)	p-value	Median (IQR)	p-value
Baseline	16 (15)		4 (3)		10.1 (7)		84 (160)		8.3 (12)
6 months	4 (8)	<0.001	1 (2)	<0.001	15.2 (10)	0.173	31.3 (61)	0.006	2.5 (3)	<0.001
12 months	3 (6)	<0.001	0 (2)	<0.001	22.4 (13)	0.043	29.7 (38)	0.012	3.2 (5)	<0.001
24 months	3.5 (7)	0.001	1 (2)	0.001			23.25 (72)	0.055	3.0 (6)	0.002

Energy density, in Joules delivered per unit volume of prostate tissue, has previously been implicated as an important factor in adequately treating larger prostates, and 3 kJ/mL has been identified as a clinically relevant cutoff value for minimum energy density.^17,18 We performed a subgroup analysis of outcomes based on patients receiving energy density 3 kJ/mL or greater vs. less than 3 kJ/mL. Our series contained 43 patients treated with ≥3 kJ/mL and 27 patients treated with less than 3 kJ/mL (median 3.7 kJ/mL vs. 2.6 kJ/mL, p < 0.001). Median prostate size was comparable between groups (200 mL vs. 217 mL, p = 0.34). Patients receiving higher energy density had significantly longer operative time (200 minutes vs. 150 minutes, p < 0.001) and laser time (105 minutes vs. 78 minutes, p < 0.001). Both groups demonstrated significant improvements compared to baseline at all endpoints (p < 0.05). At 24 months, the QoL was significantly better in the group receiving greater than 3 kJ/mL (0 vs. 1, p = 0.027). Although the high-energy density group also had a more substantial improvement in IPSS score at 24 months, this did not reach statistical significance (24 month IPSS of 2 vs. 5, p = 0.087). There were no differences in complication rates between groups (p = 0.61), and one patient from each group required retreatment.

Discussion

Although GL-XPS has emerged as a safe alternative to TURP, its safety has not been demonstrated in prostates over 150 mL that have been traditionally managed with SP or more recently HoLEP.^1,2,8 In this study, we have demonstrated the efficacy, safety, and durability of this procedure with regard to subjective symptom scores, objective voiding parameters, and complication rates in patients with median prostate volume over 200 mL. HoLEP and SP perform similarly in prostates over 100 mL,¹⁹ and our results compare favorably to these procedures, although providing lower complication rates and reduced duration of hospitalization and catheterization. Of note, HoLEP utilizes a manual enucleation technique assisted by a laser for cutting and enucleation. The enucleated tissue is then mechanically morcellated and extracted. GL-XPS vapoenucleation, however, utilizes a laser and its scope to enucleate the prostate. The enucleated tissue is then vaporized during the process to smaller fragments that can then be extracted with evacuators or graspers. This negates the use of a mechanical morcellator.

In comparing HoLEP and SP in patients with mean prostate volume 114 and 119 mL, respectively, Jones et al. demonstrated no significant differences between these two procedures in terms of objective voiding parameters, symptomatic improvement, or overall complication rates.¹⁹ Naspro et al. demonstrated improvements in Qmax after HoLEP and SP, respectively, from 7.8 and 8.3 mL/s at baseline to 22.3 and 24.2 mL/s at 12-month follow-up.²⁰ Kuntz et al. similarly demonstrated 12-month improvements in Qmax from 3.8 and 3.6 mL/s at baseline to 27.4 and 28.3 mL/s for HoLEP and SP, respectively.⁴ Our results are similar to those from these studies, as we demonstrated 12-month improvement in Qmax from 10.1 to 22.4 mL/s. Regarding subjective outcomes, we demonstrated 24-month improvement in IPSS from 16 to 3.5 and in QoL scores from 4 to 1. This efficacious and durable result compares favorably with both HoLEP and SP as demonstrated in the literature.¹⁹ Naspro et al. demonstrated 24-month improvements in IPSS after HoLEP and SP, respectively, from 20.11 and 21.6 to 7.9 and 8.1. They demonstrated improvements in QoL from 4.07 and 4.44 to 1.5 and 1.66, respectively.²⁰ Kuntz et al. did not report on QoL, but similarly demonstrated 24-month improvements in IPSS from 22.1 and 21 to 2.3 and 2.4 for HoLEP and SP.⁴

Our results are similar not only to those achieved with HoLEP and SP in large prostates but also to those achieved with the GL-XPS system in prostates under 150 mL. The GOLIATH study demonstrated noninferiority of GL-XPS compared to TURP in men with average prostate size 49 mL,⁷ and several studies have investigated GL-XPS in glands over 80 mL.^17,21,22 Hueber et al. demonstrated comparable improvements in IPSS, QoL, Qmax, and PVR between prostates greater than 80 mL and smaller than 80 mL at 6, 12, and 24 months, with the group greater than 80 mL demonstrating 24-month improvement in IPSS and QoL of 19 and 4, respectively, and improvements in Qmax of 12 mL/s and PVR from 211 to 24 mL.¹⁷ Other studies have shown similar results among various gland sizes, including a series with average prostate size 104 mL.^21,22 The longer operative time in our study is consistent with prior studies indicating that longer operative times, laser times, and energy usage are required using the GL-XPS system with increasing prostate size.^17,21
–23

In our series, the PSA level, a surrogate marker of adenoma removal,¹⁷ decreased from 8.3 ng/mL at baseline to 2.5 ng/mL at 6 months, with sustained level of 3.0 ng/mL at 24 months, a 64% reduction from baseline. Although PSA reduction is inconsistently reported in studies of HoLEP and SP, this reduction in PSA compares favorably with reports in the literature of PVP in prostates over 80 mL, with reductions of ∼40% to 45% at 12 to 24 months.^17,21

In addition to improvements in subjective and objective voiding parameters that compare favorably to those achieved with SP or HoLEP, we demonstrate excellent safety using the GL-XPS. HoLEP and SP result in rates of dysuria of 28% and 16%, respectively, in addition to bladder mucosal injury rates of 3% and 0%; transitory urge incontinence rates of 19% and 23%; acute urinary retention rates of 8% and 5%; bleeding requiring transfusion rates of 3% and 11%; urethral stricture or bladder neck stenosis rates of 2% and 4%; and overall complication rates of 64% and 63%.¹⁹ We found substantially lower rates of complications. With regard to Clavien grade I/II complications, we found a 7.1% rate of dysuria, 5.7% rate of UTI, 5.7% rate of incontinence, and 2.9% rate of refractory urinary retention. Although we had a 22.9% rate of hematuria, all cases were self-limiting and none required endoscopic intervention or blood transfusions. This rate is in line with rates of mild hematuria in other series of GL-XPS, which appear to increase with larger prostate volumes.¹⁷ Although the vapoenucleation technique attempts to achieve similar debulking to that achieved by HoLEP or SP, in general, residual tissue near the verumontanum is purposefully preserved, contributing to lower rates of postoperative transient stress incontinence.²⁴

One of the most appealing aspects of minimally invasive alternatives to SP is reduction in hospital stay and catheterization time. Jones et al. demonstrated HoLEP to have significantly reduced hospital stay and catheterization time compared to SP, with hospital stays of 65 to 70 hours compared to 130 to 251 hours.¹⁹ Furthermore,, the catheterization times for HoLEP and SP were 31 to 36 hours and 98 to 194 hours, respectively.¹⁹ Our results demonstrate further reductions in hospital stay and catheterization time; although GL-XPS may in some cases be performed as outpatient surgery, our standard practice is to keep all patients overnight, and we had over 85% of patients discharged catheter free within 1 day. A cost-effectiveness analysis conducted by Salonia et al. found that HoLEP was more cost-effective than SP, largely due to its shorter hospital stay.²⁵ Although our median operative time of 180 minutes was significantly longer than their reported operative times for HoLEP and SP, our median hospital stay of one day likely confers further cost benefit for GL-XPS, while maintaining excellent safety, efficacy, and durability at 24-month follow-up. Previous studies have reported that although large prostates required longer operative times and more energy delivery using PVP, the duration of catheterization or hospitalization was unaffected,^{17,21
–23,26} and our study confirms that the short hospital stay and duration of catheterization are preserved even in glands larger than 150 mL. This outcome is particularly notable in our cohort in which 58% of patients required an indwelling catheter preoperatively.

It is important to note that, in addition to demonstrating excellent outcomes compared to SP and HoLEP, our safety and efficacy compare well to the use of PVP in smaller glands, indicating that this appears to be a size-independent procedure.^{8,15,17,21,22} One of the most commonly cited concerns with PVP in large prostates is the increased risk of conversion to electrocautery TURP to achieve hemostasis.^14,17,27 However, there is additional evidence that bleeding can be well controlled using the laser without need for conversion.^22,28 In our experience, hemostasis was adequately achieved using the laser in all cases. Another common criticism of PVP in large glands is the potential for higher rates of retreatment. One proposed explanation for retreatment in large prostates has been that larger glands tend to receive inadequate laser energy delivery under 3 kJ/mL of prostatic tissue.^17,18 In a subgroup analysis of patients receiving 3.0 kJ/cc or greater vs. under 3 kJ/cc, there was no difference in retreatment (one patient per group), but at 24 months, the QoL was significantly better in the group receiving greater than 3 kJ/cc (p = 0.027); the IPSS also appeared to exhibit greater improvement, although it did not reach statistical significance (p = 0.087). The group receiving greater than 3 kJ/cc did, however, require significantly longer operative time and laser time. These patients had more tissue vaporized than resected, likely due to increased rates of anticoagulation and antiplatelet therapy; more of these patients were receiving warfarin and clopidogrel, although these differences were not statistically significant. Thus, although the vapoenucleation technique provides excellent long-term outcomes irrespective of prostate size, treatment with adequate energy density may be associated with improved outcomes, and the optimal energy delivery in large prostates warrants further investigation. Finally, it should be noted that large glands require experience and expertise to remove enough adenoma through a transurethral approach, which is a challenge with any technique, and the study team is highly experienced with this particular vapoenucleation technique.

The strengths of this study include the number of patients with very large prostates and the 24-month follow-up period. Limitations include the lack of follow-up data on erectile function or retrograde ejaculation, which are important outcomes to assess in future studies. Qmax was only assessed to 12-month follow-up, as uroflowmetry was inconsistently performed beyond this point. Despite these limitations, we believe this study demonstrates that this procedure is a safe, efficacious, and minimally invasive surgical treatment option that can be considered regardless of prostate size.

Conclusion

In our experience, using the vapoenucleation technique, the GL-XPS provides excellent and durable subjective and objective improvements in symptoms and voiding parameters, with no serious adverse events. This procedure is a safe and effective surgical option for patients with prostate size over 150 mL.

Footnotes

Author Disclosure Statement

B.C. is a consultant for Boston Scientific. All authors can confirm that they have no other financial relationships with any organization that might have an interest in the submitted work.

Abbreviations Used

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