Sufficient Volume Ablation with Photoselective Vaporization of the Prostate Delivers 5-Year Durability and Improves Symptom Relief for Larger Prostates

Abstract

Objectives:

To assess the long-term durability of photoselective vaporization of the prostate (PVP) for symptomatic benign prostatic enlargement (BPE) or benign prostatic obstruction (BPO) and treatment efficacy for large BPE.

Methods:

Four hundred fifty-seven patients with symptomatic BPE underwent PVP between January 2006 and April 2009. Efficacy was evaluated with the International Prostate Symptoms Score (IPSS), Quality of Life (QOL) score, urinary peak flow (Qmax), postvoid residual volume (PVR), and prostate volume. Parameters were checked preoperatively, and at 1, 3, and 5 years postoperatively. One hundred fifty-three patients completed 5-year follow-up. To assess treatment effects, patients were divided into two groups according to the preoperative prostate volume: group A (<60 mL, n=104) and group B (>60 mL, n=49).

Results:

Mean IPSS, QOL score, Qmax, and PVR improved significantly and were maintained for 5 years with no significant differences; at year 1, prostate volume had decreased significantly from 54.0 mL to 30.6 mL (43% of volume ablation) and remained at that level until year 5. Investigations according to prostate size demonstrate that IPSS and QOL scores in group B remained at significantly lower levels, and Qmax in group B improved more than in group A. 1.1% of patients needed transurethral resection of the prostate due to BPO recurrence.

Conclusions:

PVP is effective and provides durable results for 5 years, with sustained symptom relief and improved urinary flow rate, as well as a 43% volume reduction of prostate volume. Our data indicate PVP is more efficacious for larger prostates under sufficient volume ablation.

Introduction

Benign prostatic enlargement (BPE) is the most common cause of lower urinary tract symptoms (LUTS) in elderly men. Due to prostatic enlargement and failure of medical treatment, up to one-third of patients eventually need surgical intervention.¹ Transurethral resection of the prostate (TURP) has been considered the gold standard for treating BPE. Previous studies report cumulative incidences of secondary TURP at 1, 5, and 8 years of 2.9%, 5.8%, and 7.4%, respectively,² and a 162% improvement of Qmax and 70% reduction of IPSS over 5 years.³ However, TURP is associated with significant morbidity, such as perioperative hemorrhage and TUR syndrome, particularly in patients with larger prostates.

Photoselective vaporization of the prostate (PVP) with a potassium-titanyl-phosphate (KTP) laser was introduced in 2000.⁴ The KTP laser has a maximum power of 80 W, although more recently, a high-performance system using 120 W and an XPS system using 180 W have been developed. Complications related to bleeding, catheterization time, and length of hospital stay are significantly less likely with PVP, and equivalent improvements are noted for intermediate-term functional outcomes between KTP/PVP and TURP; however, long-term follow-up is being undertaken to ensure the durability of PVP.^5

–9 In addition, for small- to mid-sized prostates, KTP laser might be equivalent to TURP. For larger prostates, however, further prospective studies are warranted for PVP.³

Reported here are 5-year outcomes of PVP, including prostatic volume, to verify long-term durability and treatment effects for large BPE.

Patients and Methods

Study design

A single-center nonrandomized clinical study was carried out on patients having symptomatic BPE or benign prostatic obstruction (BPO) treated with PVP. A long-term analysis was conducted with data only on patients who could be followed up for 5 years. Inclusion criteria for 80 W GreenLight PVP were the International Prostate Symptom Score (IPSS) of 15 or more; LUTS not sufficiently controlled with medical treatment; urinary retention; endoscopically confirmed BPO; or patients who needed BPE surgery but were not considered to have indications for TURP. Complication of an overactive bladder was not considered. The study was approved by the institutional review board of our hospital. Patients were selected consecutively between January 2006 and April 2009. Written informed consent was obtained from all patients before surgery. All patient data were maintained prospectively.

Preoperative evaluations

All patients underwent evaluations of IPSS, Quality of Life (QOL) score, urinary peak flow (Qmax), postvoid residual urine volume (PVR), prostate volume measured by transrectal ultrasound (TRUS), and serum prostate-specific antigen (PSA), as well as preoperative determination of hematologic and biochemical indices. TRUS-guided prostate biopsy was performed to document the absence of adenocarcinoma of the prostate in patients who had elevated PSA levels. Backgrounds of patients at baseline are shown in Table 1.

Table 1.

Patients' Backgrounds and Perioperative Results

No. patients	Overall (n=153)	Group A (<60 mL) (n=104)	Group B (>60 mL) (n=49)	Lost to follow-up (n=283)	p Value (Group A vs B)	p Value (overall vs lost)
Age (mean±SD)	70.6±7.4	70.7±7.0	70.1±8.1	70.9±7.8	NS	NS
IPSS	21.0±7.6	20.0±6.7	23.0±8.6	23.8±7.9	0.024	<0.001
QOL score	5.28±0.88	5.20±0.92	5.44±0.78	5.38±0.82	NS	NS
Qmax, mL/s	8.76±5.28	9.60±5.3	7.00±4.7	7.36±6.4	0.005	NS
PVR, mL	107±149	92.2±149	139±147	82.6±87.8	NS	NS
Prostate volume, mL	54.0±22.9	41.9±10.9	79.1±19.6	55.1±31.1	<0.001	NS
PSA, ng/mL	6.20±7.0	5.03±6.9	8.62±6.6	7.79±10	<0.001	NS
Patients with urinary retention	16 (10.5%)	8 (7.7%)	8 (16.3%)	44 (15.5%)	NS	NS
Total energy, kJ	300.7±155.2	227.5±93.9	451.9±148	332.5±149	<0.001	NS
Operative time, min	89.4±43.6	69.5±27.1	130.1±43.0	97.3±42.8	<0.001	NS
Fibers used	1.35±0.55	1.11±0.31	1.93±0.65	1.38±0.51	<0.001	NS
Irrigation volume, L	19.8	15.8	30.1	21.2	<0.001	NS
Hemoglobin (before–after surgery), g/dL	0.80	0.82	0.77	0.81	NS	NS

IPSS=International Prostate Symptoms Score; NS=no significant difference; PSA=prostate-specific antigen; PVR=postvoid residual volume; Qmax=urinary peak flow; QOL=quality of life.

Surgical procedure

PVP procedures were performed under lumbar or general anesthesia by five surgeons. Vaporization using the KTP laser beam was continued using a side-to-side sweeping technique until an adequate cavity was created through the prostatic urethra with up to three fibers for large prostates. After each procedure, an 18F 2-way urethral catheter was inserted without continuous irrigation after checking for hemostasis. The patient was discharged after catheter removal and confirmation of smooth urination on the day following the PVP.

Outcome measures

Treatment outcomes (IPSS, QOL score, Qmax, PVR, and prostate volume) were assessed at 1, 3, 6, and 12 months after surgery, and every 6 months thereafter. In the present study, we show data at 1, 3, and 5 years after surgery. Exclusion criteria are patients who were lost to follow-up before 5 years after surgery and who had surgical interventions or cancers in the lower urinary tract during follow-up.

All data were analyzed using Student's t-test or Wilcoxon signed-rank test with p<0.05 considered statistically significant.

Results

Patients and early complications

Between January 2006 and April 2008, 457 consecutive patients underwent GreenLight PVP at our institution. Of these, 174 patients (38.1%) were followed up for 5 years; however, 21 of these patients were excluded from the 5-year evaluation because they had the pathologic conditions, as discussed later. A complete baseline with 5-year data was available for 153 patients (33.5%). Perioperative data are listed in Table 1. Of these 153 patients, 16 patients had urinary retention before surgery. Mean vaporization effectiveness was 23.3 g/300.7 kJ for tissue ablation. Operation time and delivered energy were 69.5 minutes and 227.5 kJ, and 130.1 minutes and 451.9 kJ in groups A and B, respectively (p<0.001). Hemoglobin loss during surgery was 0.82 g and 0.77 g in groups A and B (p=0.24), respectively, and no case needed blood transfusion. Ten cases of transient urinary retention, nine cases with postsurgical hemorrhage, four cases with urinary tract infection, four cases with micturition pain, two cases with transient incontinence, and one case with ureteral orifice injury were noted, but they were relieved spontaneously with or without conservative treatment. All the complications mentioned above were Grade I or II according to the Clavien Classification of Surgical Complications. No other major surgical complication was observed in the 153 patients.

Five-year durability outcome of 153 cases

Table 2 lists postoperative details of the 153 cases. All subjective and objective urinary parameters had improved significantly at 1 year (p<0.001). In addition, all parameters were maintained up to year 5. Subjective voiding scores increased slightly from year 1 to 5 (IPSS: from 7.90 to 9.03, QOL: from 1.84 to 2.03); however, statistical differences were not significant. PVR had not changed significantly by year 5. Qmax showed 203% and 194% improvement at years 1 and 5, respectively, and was not statistically significant. After surgery, the prostate volume had decreased from baseline by 43.3% at 1 year and was maintained until year 5 (42.8% decrease) with no significant difference.

Table 2.

Voiding Parameters Before and 1, 3, and 5 Years After Surgery with Comparisons of Groups Divided by Preoperative Prostate Volume

	Overall (n=153)	Group A (<60 mL) (n=104)	Group B (>60 mL) (n=49)	p Value (Group A vs B)
IPSS
Pre	21.0±7.6	20.0±6.7	23.0±8.7	0.024
1 year	7.90±5.6	8.70±6.0	6.27±4.2	0.016
Change	−62.4%	−56.5%	−72.6%	<0.01
3 years	8.53±5.9	9.56±6.4	6.51±4.4	0.005
Change	−59.4%	−52.2%	−71.7%	<0.01
5 years	9.03±6.0	10.0±6.4	7.02±4.8	0.006
Change	−57.0%	−50.0%	−69.6%	<0.01
p (1 year vs 5 years)	NS	NS	NS
QOL score
Pre	5.28±0.88	5.20±0.92	5.44±0.78	NS
1 year	1.84±1.29	2.03±1.35	1.44±1.06	0.012
Change	−65.2%	−61.0%	−73.6%	<0.01
3 years	1.94±1.26	2.14±1.27	1.56±1.16	0.011
Change	−63.3%	−58.8%	−71.3%	<0.01
5 years	2.03±1.31	2.22±1.42	1.64±0.98	0.015
Change	−61.6%	−57.3%	−69.9%	<0.01
p (1 year vs 5 years)	NS	NS	NS
Qmax mL/sec
Pre	8.76±5.28	9.60±5.3	7.00±4.7	0.005
1 year	17.8±8.6	17.6±8.9	18.1±7.7	NS
Change	203%	183%	259%	<0.001
3 years	17.4±8.0	17.1±7.6	17.9±8.8	NS
(change)	199%	178%	256%	<0.001
5 years	17.0±8.6	16.4±8.5	18.0±9.0	NS
Change	194%	170%	258%	<0.001
p (1 year vs 5 years)	NS	NS	NS
PVR mL
Pre	107±149	92.2±149	139±147	NS
1 year	32.4±33.9	34.1±35.4	28.9±30.5	NS
3 years	24.3±21.6	24.1±20.7	24.6±23.6	NS
5 years	25.4±25.3	24.5±23.9	27.2±28.2	NS
p (1 year vs 5 years)	NS	0.021	NS
Prostate volume mL
Pre	54.0±22.9	41.9±10.9	79.1±19.6	<0.001
1 year	30.6±15.4	24.2±8.9	42.9±17.4	<0.001
Change	−43.3%	−42.2%	−45.8%	NS
3 years	30.3±16.1	24.1±7.3	43.4±18.0	<0.001
Change	−43.9%	42.5%	−45.1%	NS
5 years	30.9±17.2	23.9±11	44.8±18.6	<0.001
(change)	−42.8%	43.0%	−43.4%	NS
p (1 year vs 5 years)	NS	NS	NS
PSA ng/mL
Pre	6.20±7.0	5.03±6.9	8.62±6.6	<0.001
1 year	2.99±2.75	2.40±2.42	4.19±3.00	<0.001
3 years	2.98±2.81	2.24±2.27	4.42±3.20	<0.001
5 years	3.28±3.43	2.41±2.46	4.99±4.36	<0.001
p (1 year vs 5 years)	0.002	NS	NS

PSA decreased significantly after surgery; however, it rose from year 1 to 5 with a significant difference in an overall comparison.

Difference in efficacy due to prostate volume

Because most patients with a prostate volume larger than 60 mL needed two or more laser fibers for sufficient ablation, we divided them into two groups with a cutoff prostate volume of 60 mL based on preoperative prostate volume measured with TRUS: <60 mL (group A, n=104) and >60 mL (group B, n=49). Volume reduction rates at year 1 and 5 in groups A and B were 42.4% and 43.0%, and 45.7% and 43.4%, respectively (no significant difference between groups). Preoperative PVR showed no significant difference between groups, and no significant difference was seen at each point postoperatively. PVR in group A decreased significantly from year 1 to 5. Preoperative Qmax was significantly higher in group A; however, no significant difference was seen postoperatively. Improvement ratios of Qmax in group A vs B were 183% vs 259% at year 1 (p<0.01) and 170% vs 258% at year 5 (p<0.01). Preoperative IPSS was higher in group B (p=0.024); however, postoperative IPSS in group B was significantly lower (−72.6%, −71.7%, and −69.6%) than in group A (−56.5%, −52.2%, and −50.0%) at years 1, 3, and 5 (all p<0.01). Preoperative QOL scores were not significantly different; however, postoperative QOL scores of group B were significantly lower (−73.6%, −71.3%, and −69.9%) than those of group A (−61.0%, −58.8%, and −57.3%) at years 1, 3, and 5 (all p<0.01).

Reinterventions and late complications during 5-year follow-up

Three patients (1.7%) underwent urethral dilation due to urethral stricture. Reoperation with TURP was performed in two cases (1.1%). Preoperative prostate sizes of these two cases were greater than 60 mL, and 57% and 45% volume ablations were performed, respectively. Surgical techniques were considered effective. However, prostatic re-enlargement occurred gradually and retreatment was needed at years 5 and 3.5, respectively. Seven patients (4.0%) developed bladder neck contracture (BNC) and needed transurethral resection of the bladder neck (TURBN); preoperative prostate volumes of these seven cases were less than 50 mL. Prostate biopsy was performed on patients with an elevated PSA level; prostate cancer was identified in eight patients and bladder cancer was found in one case.

Postoperative course in patients lost to follow-up

During the study period, 20.1%, 44.0%, 59.5%, and 61.9% of patients had discontinued follow-up at 1, 2, 3, and 5 years, respectively; 283 cases were lost within 5 years. Of these, 56 patients (19.7%) had urinary retention preoperatively. Preoperative parameters of the lost cohort are as follows: IPSS 23.8±7.9, QOL score 5.4±0.8, Qmax 7.4±6.4 mL/s, PVR 82.6±87.8 mL, prostate volume 55.1±31.1 mL, and PSA 7.79±9.97 ng/mL. No significant difference was seen in preoperative parameters between patients observed and lost to follow-up, with the exception of IPSS. Preoperative IPSS was significantly higher in the lost cohort (p<0.01). Postoperative IPSS, QOL score, Qmax, PVR, and prostate volume at the last visit of the lost cohort were compared with those of the observed cohort. No significant differences for each parameter were seen at each point throughout the 5 years. Thirteen cases (4.6%) needed TURBN due to BNC. Six patients (2.1%) underwent resurgery; TURP and PVP were performed in four and two cases, respectively, during the follow-up period. Urethral stricture was identified in four cases (1.4%) and required urethral dilation.

Discussion

The surgical principle for treating BPE is to reduce the prostate volume around the prostatic urethra to make a cavity for passing urine with greater force. Inadequate volume reduction might lead to recurrent LUTS and reoperation in some patients. KTP laser PVP at our institution provided about a 43% volume reduction, regardless of preoperative prostate size, and was maintained for more than 5 years. This provided sustained improvements of symptom relief and urinary flow rate. This study for the first time indicates the long-term durability of PVP as well as better treatment outcomes in patients with larger prostates under sufficient vaporization with PVP.

Many modalities of BPE surgery are available nowadays. Respective procedures have their own advantages and disadvantages. We believe three important factors are required for BPE surgery to be the gold standard: safety of procedure, technical facility, and long-term durability.

Safety of the procedure

In the present study, despite our early experiences with PVP, no major perioperative complication was identified, no blood transfusion was needed, and hemoglobin loss during PVP was negligible even in large prostates. Incidences of BNC, urethral stricture, and recurrence of BPO were 4.0%, 1.7%, and 1.1% in the observed cohort and 4.4%, 1.5%, and 1.8% in all 457 cases; these are not higher compared with other treatment modalities. Many studies compare PVP with TURP. The catheterization time, length of hospital stay, and complications related to bleeding are significantly less likely with PVP.^5,7 Therefore, the safety of PVP has been established compared with TURP.

Technical facility

The ease of surgical technique is an important factor for urologists to decide the surgical modality. The procedure of PVP is simple; laser vaporization with a side-to-side sweeping technique, while keeping a proper distance between the fiber and the surface of the adenoma, is repeated until an adequate cavity is created through the prostatic urethra. Energy output can be changed depending on the situation: vaporizing site, prostate size, or extent of hemorrhage. Thus, PVP has been more accessible to the common urologist.

Holmium laser enucleation of the prostate (HoLEP) involves a steep learning curve and relatively high rate of complications during the learning curve.^10
–12 Gomez et al. proposed that around 30–50 procedures should be conducted for most users to achieve sufficiently competence with PVP.¹³ Now, however, a simulator system is available for PVP training. This enables less experience to be required to complete PVP at the desired level and PVP facilities have been advancing; we consider the learning curve of PVP to be about 15–20 cases. Recently, HPS and XPS systems have become available and are more efficient for tissue ablation. The basic technique of PVP is common to both lasers and can be easily translated to higher powered systems. Therefore, PVP enables urologists to easily achieve further volume reductions with large prostates.

Long-term durability

Previous data demonstrate that KTP/PVP might be equivalent to TURP for small- to mid-sized prostates. For larger prostates, however, further prospective studies are warranted for PVP.³ Ruszat observed higher retreatment rates (10.3%) in patients with prostates of >80 mL compared with those with prostates of <40 mL (4.9%).¹⁴ He weighed adequate energy delivery as playing a crucial role for satisfactory outcome and retreatment rate. According to our study, the reoperation rate was only 1.1% under 43% debulking, suggesting that a sufficient volume reduction was probably achieved with our PVP.

To date, 5-year data with PVP are limited and there is no literature with an outcome longer than the 5-year follow-up. Five-year results published so far are listed in Table 3. Most omit data on prostate volume, and the 5-year follow-up rate is low.^14

–17 Hai presented 5-year data, including prostate volume, but retreatment with PVP was 7.7% under 22% volume ablation.¹⁸ So, the long-term durability of PVP has not been adequately verified.

Table 3.

Literatures on the Outcomes 5 Years After PVP

	Reference no.	IPSS% improvement	QOL score% improvement	Qmax% improvement	PVR% reduction	Prostate volume% reduction	Energy used (kJ)	Reoperation rate due to adenoma (%)	Number of patients followed up for 5 years (rate)
Ruszat	14	58.5	60.5	208	84	Unknown	206	6.8	27 (5.4%)
Malek	15	88	>90	170	84	Unknown	185	0	14 (14.9%)
Elshal	16	61.8	61.1	119	82	Unknown	144.5	5.5	75 (82%)
Malde	17	58.4	Unknown	174	76.5	Unknown	113	17.7	56 (49%)
Hai	18	79	80.1	172	77.1	21.9	Unknown	7.7	246 (77%)
Otsuki	Present study	57	61.6	194	76.5	42.8	300.7	1.1	153 (33.5%)

HoLEP is an excellent procedure effective for debulking prostatic adenoma and also has long-term durability.^19
–21 A substantial PSA reduction is about 75%–90% after HoLEP and this is an indirect sign of its ablative capabilities.^22
–24 PSA reduction in this study is 51.5%, which is smaller than that achieved with HoLEP. Indeed, the tissue ablation rate might be smaller with PVP, but our study elucidated that long-term durability is comparable to TURP or HoLEP. Achieving more than a 40% volume reduction might be considered sufficient ablation and an appropriate goal of a vaporization technique. The present study reveals PVP has sustainable long-term outcomes over 5 years; therefore, we believe PVP can be considered the gold standard for BPE/BPO surgery.

Good indications for PVP

Interestingly, our investigation also indicates that PVP is more efficacious for patients with larger prostates according to evaluations of IPSS, QOL score, and Qmax. In our previous literature, better treatment outcomes with larger prostates were confirmed from 1-year observations²⁵ and were reconfirmed at 5-year follow-up. This finding affirms the opinion of Littlejohn et al. that patients with the largest prostates and the most tissue resected are apt to improve the most.²⁶

Postoperative course of lost cohort

A comparison of preoperative urinary conditions reveals IPSS is significantly higher in the lost cohort. On the other hand, postoperative subjective symptoms and voiding parameters do not show a significant difference between patients observed and lost throughout the 5 years. Before this study, we speculated that the postoperative course of the lost cohort was better compared with the observed cohort; Since the patients felt more satisfied with PVP treatment, a sense of duty to receive periodic checks faded and they ceased coming to the hospital. Our speculation was partly correct because subjective improvements of urinary symptoms in the lost cohort were higher than in observed patients. Furthermore, the last follow-up data of the lost cohort are not significantly different from those of the study group over 5 years; therefore, the postoperative course of many patients of the lost cohort could be considered as good as that of the observed cohort. Incidences of resurgery, BNC, and urethral stricture were 2.1%, 4.6%, and 1.4%; these were not significantly different from those of the observed cohort. Therefore, it can be said that 5-year follow-up data are representative of the results of all patients who underwent PVP in this study.

Limitations

This study has some limitations: single-center study, high rate of follow-up loss, and small sample size. Lack of follow-up in a surgical trial is a serious problem. Five-year follow-up rates reported by Malek and Ruszat were 14.9%¹⁵ and 5.4%,¹⁴ respectively, whereas the 5-year follow-up of the present study is 33.5%. The fact that patients who undergo BPE treatment are in late middle age or old age and BPE is a benign disease, complicates execution of a long-term follow-up study. We followed up more than 150 patients not only for functional outcomes but also for prostate volumes. The reoperation rate was low with sufficient vaporization. This study demonstrates the long-term durability of KTP/PVP. Longer follow-up studies are required to confirm the clinical benefits of this technique for the surgical management of LUTS/BPE.

Conclusions

Using the PVP technique for BPE is safe and efficacious and provides durable results for more than 5 years, with improvements maintained for symptom relief, urinary flow rate, and treatment satisfaction in patients with larger prostates receiving 43% volume debulking. Furthermore, the technique produces better treatment outcomes in patients with larger prostates. PVP may be considered the gold standard for BPE surgery with sufficient volume ablation.

Footnotes

Author Disclosure Statement

Yoshitaka Kuwahara, Takuji Tsukamoto, and Hideo Otsuki are advisors for MC MEDICAL, INC. (MCM)—the Japanese national distributor for American Medical Systems—and Yoshitaka Kuwahara and Hideo Otsuki received honoraria from MCM for presentations.

Abbreviations Used

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