Safety,Perioperative,and Early Functional Outcomes of Vapor Incision Technique Using the GreenLight XPS 180 W System: Direct Comparison with Photoselective Vaporization of the Prostate

Abstract

Objectives:

To compare perioperative parameters, safety, and short-term functional outcomes between GreenLight 180 W-XPS photoselective vaporization of the prostate (PVP) and vapor incision technique (VIT).

Materials and Methods:

A total of 956 men were treated at five high-volume centers in Canada and the United States between 2000 and 2014 for benign prostatic hyperplasia. Perioperative parameters, complications, and early functional outcomes were retrospectively compared. One-to-one propensity score matching was performed to adjust for baseline differences between treatment groups. Subgroup stratified comparative analysis was performed according to preoperative prostate volume 80 cc or less vs greater than 80 cc on transrectal ultrasound (259 and 185 patients, respectively).

Results:

VIT allowed greater energy delivery and energy density, but operative time and laser time were longer with greater use of MoXy fibers when compared with PVP (all p < 0.05). Improvements in outcomes at 6 months, including International Prostate Symptom Score, quality of life score, and uroflowmetry parameters, were significantly greater after VIT when compared with baseline. VIT was associated with significantly greater 6-month prostate-specific antigen (PSA) reduction (63% vs 50%, p = 0.01). No differences in intraoperative complications were observed between treatment groups.

Conclusion:

VIT is safe and efficacious, providing greater improvements in functional outcomes and PSA reduction at 6 months in comparison with PVP. These results reflect the larger amount of adenoma removed. Yet, it is associated with longer operative time and greater use of MoXy fibers. Long-term follow-up is needed to accurately assess functional outcomes and retreatment rates.

Introduction

Benign prostatic hyperplasia (BPH) refers to the proliferation of smooth muscle and epithelial cells within the transition zone of the prostate; it is a pathologic process that contributes to lower urinary tract symptoms (LUTS) in aging men. Failure of medical therapy and disease progression often require bladder outlet obstruction surgery.¹ Transurethral resection of the prostate (TURP) and open prostatectomy are considered the gold standard in the surgical treatment for BPH. Yet, their use has declined in the past decades with the introduction of new minimally invasive surgical treatments such as the GreenLight laser technology with the development of three laser generations: 80 W Potassium Titanyl Phosphate (KTP), 120 W High Performance System (HPS), and 180 W Xcelerated Performance System (XPS).²

Laser prostatectomy has gained widespread acceptance in the United States,³ Canada,⁴ and Europe⁵ due to its well-documented safety and efficacy in the treatment of non-neurogenic male LUTS.^6

–9 Due to technical challenges associated with the treatment of larger glands leading to a higher retreatment rate,¹⁰ the concepts of vaporization incision and vapoenucleation of the prostate were developed to improve outcome durability by adenoma resection and enucleation, respectively.^11,12

As such, we sought to compare photoselective vaporization of the prostate (PVP) and vapor resection (or vapor incision technique [VIT]) in terms of perioperative parameters, safety, and functional outcomes at 6 months in a large multi-institutional cohort. We particularly examined the effect of prostate volume (PV) on functional outcomes and prostate-specific antigen (PSA) reduction.

Materials and Methods

Study population

After institutional review board approval, data were retrospectively collected for men with LUTS secondary to BPH treated with laser prostatectomy using GreenLight XPS-180 W between August 2010 and August 2014. All procedures were performed in five high-volume centers in Canada and the United States by five experienced surgeons (Fig. 1). Surgical indications were based on established guidelines of the American Urological Association⁶ and the Canadian Urological Association.⁹ Patients with prior pelvic radiation, histological diagnosis of prostate cancer, diagnosis of neurogenic bladder or impaired detrusor contractility, neurologic disorder, and artificial urinary sphincter were excluded from this study.

FIG. 1.

(A) Distribution of photoselective vaporization of the prostate cases among surgeons. (B) Distribution of vapor incision technique cases among surgeons.

Surgical technique

PVP was performed with the use of the XPS-180 W system as previously described.¹³ VIT involved adenoma incisions at 5- and 7-o'clock positions, followed by 3-, 9-, and 12-o'clock down to the surgical capsule.¹⁴ Side-fire vaporization along the capsule was carried out, thereby permitting tissue excision rather than pure vaporization. Liberated tissue fragments were then retrieved from the bladder with grasping forceps or transurethral loops. All cases were conducted with a 23F continuous flow cystoscope and a 30° lens used at a maximum power of 180 W for vaporization with the MoXy 650 kJ fiber. TruCoag feature pulse modulated at 12 Hz and 5–40 W was used for coagulation. Physiologic saline at room temperature was used as irrigation fluid.

Procedures were performed under general or spinal anesthesia and antibiotic prophylaxis was administrated according to published guidelines.

The choice of treatment type (vaporization only vs vapor resection) was left to the surgeon's preference. Three of five surgeons also performed VIT in addition to PVP.

Assessment

We retrospectively collected preoperative data, including PV measured by transrectal ultrasound (TRUS) along with uroflowmetry parameters (postvoid residual urine volume [PVR] and maximum urinary flow rate [Qmax]), International Prostate Symptom Score (I-PSS), quality of life (QoL) score, and PSA.

Operative parameters such as operative time, laser time, number of fibers, total energy, and energy density (ratio of the amount of energy delivered during treatment to PV) were also collected.

Outcomes

Safety was evaluated by measuring the complications related to primary treatment. Adverse postoperative events were reported according to the Clavien-Dindo grading system and divided into early vs delayed complications.¹⁵ Intraoperative events were reported separately. Postoperative visits and admissions due to complications were also reported.

Efficacy was assessed by quantitative uroflowmetry parameter improvements as well as subjective I-PSS, including the QoL score, 6 months after XPS-180 W treatment. Additionally, PSA reduction served as a surrogate marker of tissue removal.

Subgroup stratified comparative analysis was performed according to preoperative PV 80 cc or less vs greater than 80 cc on TRUS. The effect of prostate size on 6-month functional outcomes and PSA reduction was compared according to treatment type.

Statistical analyses

We relied on propensity score matching to adjust for differences in baseline characteristics between treatment groups. Patients were selected for the analysis by one-to-one propensity score matching without replacement using a caliper width of 0.02 on the propensity score.¹⁶ The propensity score was estimated by logistic regression of the treatment type on the following baseline characteristics: age, American Society of Anesthesiologists score, current anticoagulation use, preoperative urinary retention, and PV measured by TRUS. Only patients with complete follow-up data at 6 months were included in the final data analysis. Differences between treatment groups were assessed for statistical significance using the Wilcoxon rank sum test for continuous variables and the chi-square or Fisher exact test for categorical variables. To compare the two subgroups of patients with PV 80 cc or less vs greater than 80 cc according to treatment type at baseline and at 6-month follow-up, we used the Mann–Whitney U-test for median comparisons and the Student t-test for mean comparisons. All tests were two-sided with p < 0.05 considered statistically significant. Statistical analyses were performed using Statistical Analysis System 9.2.

Results

Patient characteristics

Overall, 956 patients were included in this study: 672 (70.4%) and 284 (29.6%) patients underwent PVP and VIT, respectively. No differences between treatment groups were detected in age, previous BPH surgery, and anticoagulation use (Table 1). However, the vapor resection group had a greater PV (83.4 vs 73.3 cc) and a higher rate of preoperative urinary retention (18.0% vs 31.8%) (both p < 0.001). Likewise, these patients had a higher I-PSS and QoL, a greater PVR, a lower Qmax, and a higher PSA at baseline when compared with the vaporization-only group (all p ≤ 0.001).

Table 1.

Baseline Patient Characteristics of 956 Patients Treated with Laser Prostatectomy Using GreenLight XPS-180 W System for Benign Prostatic Hyperplasia Between 2010 and 2014 Before and After Propensity Score Matching

	Before propensity score matching			After propensity score matching
	PVP	VIT	p	PVP	VIT	p
No. of patients	672	284	—	222	222	—
Mean age (years)	68.8	68.0	0.230	68.2	67.9	0.75
ASA ≥3 (%)	180 (27.0)	93 (33.7)	0.048	68 (30.6)	68 (30.6)	1.00
Previous BPH surgery (%)	149 (22.3)	51 (18.2)	0.155	38 (17.1)	36 (16.5)	0.87
Anticoagulation use (%)	48 (7.7)	18 (6.4)	0.477	9 (4.1)	12 (5.4)	0.50
Mean I-PSS	18.8	22.2	<0.001	20.6	22.6	0.07
Mean QoL	3.8	4.3	<0.001	4.1	4.3	0.33
Mean Qmax (mL/s)	9.3	7.3	<0.001	8.2	7.1	0.017
Mean PVR (mL)	183	251	0.001	221	255	0.24
Mean PSA (ng/mL)	4.3	5.9	<0.001	4.0	6.1	0.003
Mean prostate volume (g)	72.7	83.5	<0.001	83.8	82.1	0.49
Preoperative urinary retention (%)	118 (18.0)	86 (31.6)	<0.001	71 (32.0)	69 (31.1)	0.84

ASA = American Society of Anesthesiologists; BPH = benign prostatic hyperplasia; I-PSS = International Prostate Symptom Score; Qmax = maximum urinary flow rate; QoL = quality of life; PSA = prostate-specific antigen; PVP = photoselective vaporization of the prostate; PVR = postvoid residual urine volume; VIT = vapor incision technique.

To adjust for these preoperative differences, one-to-one propensity score matching resulted in 222 patients from each treatment group with a PVP control for each VIT case. The mean standardized differences in patient characteristics between the two matched groups were less than 10%, indicating a high degree of similarity in the distribution of both populations. Mean PV was 83.8 and 82.1 cc for the PVP and VIT cases, respectively (p = 0.49). The only statistically significant baseline differences were a higher Qmax (8.2 vs 7.1 mL/s, p = 0.017) and a lower PSA (4.0 vs 6.1 ng/mL, p = 0.003) in the vaporization-only group.

Perioperative parameters

While vapor resection allowed for greater energy delivery (338 vs 274 kJ, p < 0.001) and energy density (4.8 vs 3.5 kJ/cc, p < 0.001) when compared with vaporization only, operative time (74.4 vs 54.4 min, p < 0.001) and laser time (38.7 vs 34.4 min, p = 0.007) were longer.

Moreover, VIT had greater need for 2 MoXy fibers or more (16.7% vs 4.5%; p < 0.001). Length of stay and catheterization duration were similar between both groups (Table 2).

Table 2.

Perioperative Parameters

	After propensity score matching
	PVP (n = 222)	VIT (n = 222)	p
Mean operative time (minutes)	54.4	74.4	<0.001
Mean laser time (minutes)	34.4	38.7	0.007
Mean energy (kJ)	274	338	<0.001
Mean energy per gram of prostate (kJ/g)	3.5	4.8	<0.001
Fiber use (%)
1	95.5	83.3	<0.001
≥2	4.5	16.7

Functional outcomes

At 6 months, the VIT group experienced greater changes in I-PSS (−18 vs −15, p = 0.009) and QoL (−3.4 vs −2.7, p < 0.001) when compared with the PVP group. Moreover, vapor resection demonstrated greater improvements in the uroflowmetry parameters such as Qmax (+14.0 vs +10.5 mL/s; p = 0.002) and PVR (−252 vs −178 mL; p = 0.01). Furthermore, the median 6-month PSA reduction was greater with VIT (63.0% vs 50.0%; p = 0.01; Table 3). Additionally, subgroup stratified comparative analysis showed a greater PSA reduction after vapor resection for the greater than 80 cc group in comparison with vaporization-only group (65.2% vs 42.2%, p = 0.009; Table 4).

Table 3.

Six-Month Postoperative Outcomes

	After propensity score matching
	Baseline			6 months
	PVP	VIT	p	PVP	VIT	p
I-PSS
Mean I-PSS	20.6	22.6	0.07	6.6	5.6	0.59
ΔI-PSS	—	—	—	−15	−18	0.009
QoL
Mean QoL	4.1	4.3	0.33	1.3	1.1	0.57
ΔQoL	—	—	—	−2.7	−3.4	<0.001
Qmax
Mean Qmax	8.2	7.1	0.017	17.6	19.9	0.008
ΔQmax	—	—	—	10.5	14.0	0.002
PVR (mL)
Mean PVR	221	255	0.24	55	26	<0.001
ΔPVR	—	—	—	−178	−252	0.01
PSA (ng/mL)
Median PSA	3.1	4.3	0.003	1.2	1.2	0.74
ΔPSA (%)	—	—	—	−50.0	−63.0	0.01
ΔPSA	—	—	—	−1.1	−2.0	<0.001

Table 4.

Six-Month Prostate-Specific Antigen Change (%) from Baseline Overall and by Prostate Volume Subgroup

	After propensity score matching
	PVP	VIT	p
Overall (n = 444)	−50.0	−63.0	0.01
PV 80 cc or less (n = 259)	−50.0	−60.0	0.207
PV greater than 80 cc (n = 185)	−42.2	−65.2	0.009

PV = prostate volume.

Complications

As shown in Table 5, there were no differences in intraoperative or postoperative adverse events between both groups aside from more early postoperative (i.e., within 90 days of surgery) Clavien-Dindo grade II complications after pure vaporization such as urinary tract infections and hematuria. Likewise, postoperative emergency room visits and hospitalizations for complications were similar (all p > .05). However, in the early postoperative period, there were more clinic visits for men treated by PVP (14.4% vs 5.9%, p = 0.004; Table 6).

Table 5.

Treatment-Related Adverse Events

	Intraoperative
Adverse events	PVP (n = 222)	VIT (n = 222)
Capsular perforation	0 (0)	1 (1)
Bleeding, hematuria	1 (1)	0 (0)

	Postoperative ≤90 days		Postoperative >90 days
	PVP (n = 222)	VIT (n = 222)	PVP (n = 222)	VIT (n = 222)
Clavien-Dindo grade I
LUTS	1 (1)	2 (1)	1 (1)	0 (0)
Urinary incontinence (1 pad/day)	2 (2)	2 (2)	0 (0)	0 (0)
Erectile dysfunction (de novo)	0 (0)	0 (0)	0 (0)	1 (1)
Urinary retention	1 (1)	0 (0)	0 (0)	0 (0)
Total grade I	4 (4)	4 (3)	1 (1)	1 (1)
Clavien-Dindo grade II
UTI	10 (10)	4 (4)	1 (1)	0 (0)
Fever	1 (1)	0 (0)	0 (0)	0 (0)
Prostatitis	1 (1)	0 (0)	0 (0)	0 (0)
Urethral injury	1 (1)	0 (0)	0 (0)	0 (0)
Bleeding, hematuria	5 (5)	0 (0)	0 (0)	0 (0)
Urinary incontinence (>1 pad/day)	4 (4)	1 (1)	1 (1)	0 (0)
Erectile dysfunction (worsening)	0 (0)	0 (0)	1 (1)	0 (0)
LUTS	13 (13)	8 (7)	1 (1)	0 (0)
Cardiac arrhythmia	1 (1)	1 (1)	0 (0)	0 (0)
Urinary retention	9 (9)	7 (7)	0 (0)	0 (0)
Other	2 (1)	0 (0)	0 (0)	0 (0)
Total grade II	47 (46)	21 (20)	4 (4)	0 (0)
Clavien-Dindo grade IIIa/IIIb
Bleeding, hematuria	2 (2)	1 (1)	1 (1)	2 (2)
Urinary retention	1 (1)	0 (0)	0 (0)	0 (0)
Bladder neck/urethral stricture	0 (0)	1 (1)	1 (1)	2 (2)
Renal insufficiency	1 (1)	0 (0)	0 (0)	0 (0)
Urinary incontinence	1 (1)	0 (0)	0 (0)	1 (1)
LUTS	1 (1)	0 (0)	0 (0)	0 (0)
Total grade III	6 (6)	2 (2)	2 (2)	5 (5)

Results presented as number of events (number of subjects). Statistically significant differences between treatments are indicated by bold font.

UTI = urinary tract infection.

Table 6.

Postoperative Visits for Complications

	After propensity score matching
	≤90 days			>90 days
Type of visit	PVP (n = 222)	VIT (n = 222)	p	PVP (n = 222)	VIT (n = 222)	p
ER visit (%)	11 (5.0)	10 (4.5)	1.00	0 (0.0)	0 (0.0)	NA
Hospitalization/ICU/CUU admission (%)	7 (3.2)	2 (0.9)	0.175	0 (0.0)	3 (1.4)	0.248
Clinic visit (%)	32 (14.4)	13 (5.9)	0.004	7 (3.2)	5 (2.3)	0.771

CUU = coronary care unit; ER = emergency room; ICU = intensive care unit; NA = not applicable.

Discussion

GreenLight PVP for the treatment of enlarged prostates remains a challenge and is often associated with longer operative time, more laser fiber usage, and insufficient tissue removal requiring retreatment.¹⁰ Hueber and colleagues reported a retreatment rate of 1.2% at 24 months in a multicenter study using the 180 W XPS system with a mean PV of 120 cc in the retreatment group.¹⁷ In contrast, holmium laser enucleation of the prostate (HoLEP) has already been well demonstrated as a size-independent surgical approach since its initial description by Fraundorfer and Gilling.¹⁸ Yet, the challenging learning curve, higher equipment costs, and increased operative time have limited its widespread acceptance and hindered its establishment as a gold standard procedure.¹⁹ These limitations have fueled the development of hybrid laser techniques with the goal of size-independent procedure. The initial reports of such techniques were with holmium laser resection of the prostate (HoLRP).²⁰ In their 4-year follow-up randomized trial, Westenberg and colleagues found that HoLRP and TURP were equivalent in long-term results, but HoLRP was associated with less perioperative morbidity.²¹

Growing experience with the GreenLight laser technology has enabled a shift toward newer surgical techniques combining vaporization with resection and enucleation (vaporesection and vapoenucleation, respectively) with the goal of treating larger prostates.¹¹ Recent report by Misrai and colleagues compared PVP with GreenLight laser enucleation of the prostate (GreenLEP) in 120 patients with PV greater than 80 cc. The authors found shorter surgical time, lower rate of unplanned hospital readmission, and higher decreases in 6-month PSA and PV with GreenLEP.

The current study is the largest to date to report outcomes with vaporesection and vaporization-only technique using the latest XPS-180 W system. Several other vaporization resection techniques were reported with the previous GreenLight systems. Sandhu and Te initially described a VIT in 2005 using the KTP-80 W system.²² Although the first generation had limited power compared with the current 180 W XPS system, the technique was developed specifically to enhance prostatic tissue resection in larger glands by incising down to the surgical capsule while also allowing the surgeon to obtain prostatic tissue for pathologic evaluation. Compared with standard photoselective vaporization, this new technique was found to decrease operative time per PV; nonetheless, I-PSS and uroflowmetry parameters at 1 and 3-month follow-up showed no significant differences between both techniques. Subsequently, Son and colleagues described a modified vaporization resection technique called the Seoul technique using the HPS-120 W system.¹⁴ They reported the results of 104 patients with PV over 40 cc treated either with the vaporization-only technique (n = 40) or the Seoul technique (n = 64). Although greater volume reduction per energy, per laser time, and per operative time were achieved with the Seoul technique, reflecting the increased efficacy of tissue removal, the clinical outcomes were equivalent without detected differences at 12 months.

In our experience, VIT was associated with prolonged laser time (38.7 vs 34.3 min) and operative time (74.4 vs 54.4 min; all p < 0.001). More recently, Ben-Zvi published a retrospective series of 25 consecutive patients with PV over 80 cc treated with VIT compared with a size-matched cohort treated with vaporization only using the HPS-120 W system.²³ VIT allowed for reduced mean laser time (35 vs 48 min), operative time (63 vs 80 min), and energy use (227 vs 325 kJ; all p < 0.05).

Patients in our cohort had significantly larger prostates. This could be, in part, explained by a learning curve effect and by the additional time needed to extract the resected adenoma fragments from the bladder using grasping forceps or transurethral loops. Tissue fragments were often too large for Toomey syringes, thus TURP with TUR loops was seldom used. Not surprisingly, in comparison with the previous retrospective vapor resection series, the overall energy delivery was greater with the XPS-180 W system compared with the KTP-80 W and HPS-120 W systems.^14,23 Additionally, the greater energy usage and the use of mechanical dissection resulting in fiber damage during vapor resection could explain the higher use of MoXy fibers per case. This is inherently associated with increased costs and needs to be taken into consideration.

It has been suggested that PSA decrease can serve as a surrogate marker for adenoma removal.¹⁷ Indeed, Hueber and colleagues reported that energy density superior to 4 kJ/cc and a drop of more than 50% in PSA at 3 months are potential predictors of durable long-term outcomes. Furthermore, a recent report by Valdivieso and colleagues concluded that increased energy density was associated with a more significant PSA reduction (>50%) at follow-up, suggesting increased vaporization of adenoma.²⁴ In the current report, we found that energy density is significantly higher with vapor resection (4.8 vs 3.5 kJ/cc, p < 0.001). In addition, it is important to note that postoperative PSA reduction was greater with VIT when compared with PVP at 6 months (63.0% vs 50.0%, p = 0.01). More importantly, the difference was greater in the PV greater than 80 cc group after vapor resection (65.2% vs 42.2%, p = 0.009). These results are similar to that obtained after HoLEP or GreenLEP.²⁵ This suggests that the VIT can produce greater removal of adenoma tissue, possibly approaching enucleation-like defects. Postoperative TRUS would have been valuable for accurate assessment of tissue removal; however, there was variability among surgeons in follow-up measurements.

Concerning functional outcomes, our study showed greater changes in I-PSS and QoL and greater improvements in the uroflowmetry parameters significantly favoring GreenLight vaporesection.

With regard to safety, no differences were noted in intraoperative adverse events. Specifically, VIT did not lead to higher rates of capsular perforation or conversion to TURP. Compared with previous reports with vapoenucleation, VIT was not associated with increased stress urinary incontinence. However, men treated with PVP had more Clavien-Dindo grade II early postoperative complications.

Moreover, men in the PVP group were more likely to consult at the clinic in the early postoperative period compared with men in the VIT group. This could be explained, in part, by the higher rate of postoperative LUTS with vaporization-only procedures (6.8% vs 3.6%, p = 0.198).

Several limitations of this study are worth mentioning. The major shortcomings of the current study are related to its retrospective nonrandomized design, although propensity score matching was used to account for inherent differences in baseline characteristics between treatment groups. Moreover, one can speculate the possible selection bias toward vapor resection in patients with larger prostates (>80 cc). This could be related to the perception that VIT results in larger amount of adenoma removal. Additionally, the lack of cost evaluation could be regarded as a flaw. The learning curve remains to be evaluated. More importantly, longer follow-up is required to accurately assess the functional outcomes and retreatment rates.

In spite of the limitations listed above, to our knowledge, this study is the largest to compare vaporization-only and VIT and the first to report outcomes with the latest XPS-180 W system.

Conclusion

VIT using the GreenLight 180 W-XPS system is safe and efficacious in the treatment of BPH. This hybrid technique provides greater improvements in early functional outcomes and PSA reduction in comparison with PVP. These results reflect the larger amount of adenoma removal with vaporesection. Yet, it is associated with longer operative time and greater use of MoXy fibers. Long-term follow-up is needed to accurately assess the durability of the functional outcomes and the retreatment rates.

Footnotes

Acknowledgment

The current abstract was featured in the Socitété Internationale d'Urologie 2016 congress in Buenos Aires, Argentina.

Author Disclosure Statement

M.A.H., R.R.G., G.R.E., L.S.K., V.M., and K.C.Z. are consultants for American Medical Systems.

Abbreviations Used

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