Comparison of vaporization using 120-W GreenLight laser versus 2-micrometer continuous laser for treating benign prostatic hyperplasia: A 24-month follow-up study of a single center

Abstract

OBJECTIVE:

To evaluate safety, efficacy, and long-term outcomes of photoselective vaporization of prostate using 120-W HPS GreenLight KTP laser and compare the results with those obtained with 2-micrometer continuous-wave (2 um CW) laser for treatment of patients with benign prostatic hyperplasia (BPH).

MATERIALS AND METHODS:

One group of 216 patients diagnosed with BPH underwent 120-W KTP laser vaporization of the prostate, while another group of 198 BPH patients underwent 2 um CW laser vaporization. The relevant pre-, peri-, and post-operative parameters were compared between the two therapy groups. Functional results in terms of improvement of International Prostate Symptom Score (IPSS), maximum flow rate (Qmax), and post-void residual (PVR) urine were assessed at 3, 6, 12, and 24 months.

RESULTS:

BPH was successfully treated with 120-W HPS KTP laser and 2 um CW laser in all patients. There were no significant difference between two patient groups in the baseline characteristics (such as PSA, IPSS, QoL, and Qmax). No major complications occurred intraoperatively (capsule perforation and TUR syndrome) or postoperatively (electric unbalance), and no blood transfusions were required in both groups. Average catheterization time was 1.9±1.3 days for the 120-W PVP and 2.2±1.9 days for the 2 um CW laser treatment. In addition, the hospitalization times were 3.8±1.2days (120-W PVP) and 4.8±1.5 days (2 um CW laser), respectively. The incidence of dysuria and urge incontinence was higher in the 2 um CW laser group (35/198, 24/198) than in the 120 W PVP group (15/216, 10/216). Dramatic improvement was observed in Qmax, IPSS, Qol, and PVR as compared with the respective pre-operative values. The degree of improvement during the follow-up period was comparable in both groups. No significant differences were observed in terms of re-operation rates, bladder neck stricture, and urethral stricture.

CONCLUSIONS:

Both 120-W HPS laser and 2 um CW laser vaporization present effective treatment options in patients with BPH, but 120-W PVP provides safer therapy with less post-operative complications within the 2-year follow-up period.

Keywords

Benign prostatic hyperplasia (BPH) treatment laser surgery vaporization outcomes

1 Introduction

Benign prostatic hyperplasia (BPH) is the most common disease in aging men, and its incidence increases with age. The prevalence of BPH among men in their 50 s and 60 s is 50%. It is then rising to 90% by the age of 80 s and beyond, based on autopsy findings [1, 2]. Nearly 50% of the men older than 60 years often have lower urinary tract symptoms (LUTS) secondary to BPH [3]. Although the transurethral resection of the prostate (TURP) procedure is still regarded as the golden standard for the treatment of lower LUTS due to BPH, it is associated with significant morbidity [4]. In the last decade, several transurethral techniques were developed to overcome the morbidity of TURP while maintaining its efficacy [5, 6]. During the past decade, laser prostatectomy, a mini invasive treatment for LUTS due to BPH, has become increasingly popular owing to the reduction in intro-operative morbidity [7 –9] and its high safety [10]. From the early procedure of interstitial laser coagulation through to the use of holmium laser enucleation of the prostate, there has been a growing body of evidence on the efficacy of these procedures [11].

In the past decade, a continuous-wave (CW) thulium laser device which emits at a wavelength of 2 um has been introduced, which allows the simultaneous vaporization and resection of the prostate [12, 13]. The effectiveness of the 2 um laser application for the complete removal of the prostatic lobes is considered similar to that of open prostatectomy and superior to open prostatectomy, because it is a minimally invasive approach without unnecessary thermal damage [14]. The thulium: YAG laser energy is emitted in a continuous-wave and induces an “eschar-like” effect on the surface of the incised tissue. This fact and the mainly blunt dissection with subsequent laser coagulation of the vessels might have contributed to the longer time spent to dissect in the correct plane [8]. Many studies have shown that it is a safe and effective surgical treatment for BPH patients with good hemostasis and no damage to surrounding structures [15 –17].

Another newer laser technology is the potassium-titanyl-phosphate (KTP) laser, which has been introduced as a substitute treatment for patients with LUTS. Photoselective vaporization of the prostate (PVP) is expected to offer more effective and safer therapy to patients than TURP [18 –23]. The KTP laser is fully transmitted through the aqueous irrigant but is highly absorbed by oxyhemoglobin in the tissue. This specificity allows the laser energy to be selectively absorbed by the tissue with high oxyhemoglobin content, such as the prostatic tissue. Hence, with use of optimum technique, the vaporization is precisely focused, and the short optical penetration at this wavelength confines the high-power laser energy to the superficial layer of the prostatic tissue with only 1– 2 mm coagulation [24, 25]. Many studies have also demonstrated that the treatment with 120-W-HPS GreenLight is a safe and effective procedure for BPH patients and non-muscle invasive bladder cancer [26]. Both procedures have been shown to be superior to the TURP procedure, but the reports of long-term results of clinical comparisons between the efficacy of 120-HPS GreenLight and 2-micrometer continuous-wave laser treatments are still limited.

Therefore, the aim of this study was to compare the long-term results in terms of efficacy and side effects between 120-HPS GreenLight and 2-micrometer continuous-wave laser treatments 24 months after the treatment of patients in our hospital.

2 Materials and methods

2.1 Study population

From October 2013 to October 2015, a total number of 414 patients with LUTS secondary to BPH were randomly enrolled in either group: the 120-W-HPS photo-selective vaporization of the prostate (PVP) (n = 216) or the 2 um laser group (n = 198) in our unit. All patients provided an informed written consent, and the study was approved by our Ethical Committee. The following inclusion criteria were applied: existence of comorbidities, medical therapy failure, presence of moderate or severe lower urinary tract symptoms (LUTS) (International Prostate Symptom Score (IPSS) >7), maximum urinary flow rate (Qmax) <15 mL/sec, and post-voiding residual urine volume (PVR) >50 mL. Patients with prostate or bladder cancer, urethral stricture, and prostate cancer, and men with neurogenic voiding dysfunction were excluded from the study. In cases of suspicion of prostate cancer with TRUS, DRE, or high-level PSA, TRUS-guided prostate biopsies were performed to exclude prostate cancer.

The efficacy and safety between the two surgical procedures were investigated in this investigation. Prior to the operation, the condition of all patients was evaluated by a general and urological examination, which included medical history inspection, routine blood test, blood analysis including coagulation parameters, urine analysis, serum prostate specific antigen (PSA) level, serum creatinine, electrocardiogram, echocardiography, digital rectal examination (DRE), transrectal and abdominal ultrasonography, and heart and lung function. Before the operation, all patients were asked to complete the International Prostate Symptom Score (IPSS) and Quality of Life (QoL) score questionnaires. The post-void residual volume (PVR) and the maximum urinary flow rate (Qmax) were assessed by abdominal ultrasonography and uroflowmeter, respectively. Urinary retention was preoperatively present in 58 patients of the 120-W PVP and 62 patients of the 2 um laser, which necessitated the placement of a transurethral or suprapubic catheter.

No significant difference was found in the basic characteristics between the patients of the two groups studied (Table 1). Oral anti-coagulation was administered in 45 cases of the 120-W PVP and 50 cases of the 2 um laser group.

Table 1
Baseline characteristics in BPH patients with two procedures

Variables 120 W PVP 2 um Laser P Value

Cases 216 198

Age (years) 72.7±4.7 70.7±3.7 ns

PSA (ng/ml) 3.57±3.29 3.24±3.62 ns

IPSS 25.6±5.2 27.6±4.9 ns

Qol 4.21±0.53 4.33±0.66 ns

Qmax(ml) 7.5±2.1 6.9±2.3 ns

Prostate volume(ml) 82±26.3 86±28.1 ns

PVR(ml) 125.3±72.7 135.3±89.7 ns

Oral anticoagulation 45(21%) 50(25%)

Variables	120 W PVP	2 um Laser	P Value
Cases	216	198
Age (years)	72.7±4.7	70.7±3.7	ns
PSA (ng/ml)	3.57±3.29	3.24±3.62	ns
IPSS	25.6±5.2	27.6±4.9	ns
Qol	4.21±0.53	4.33±0.66	ns
Qmax(ml)	7.5±2.1	6.9±2.3	ns
Prostate volume(ml)	82±26.3	86±28.1	ns
PVR(ml)	125.3±72.7	135.3±89.7	ns
Oral anticoagulation	45(21%)	50(25%)

All values except the values in percentage as mean±standard deviation, two-sided t test.

2.2 Surgical technique

The surgical procedures of BPH using 120-W-HPS GreenLight and 2 um micrometer continuous-wave laser are similar. The techniques of PVP and 2 um laser were performed as previously described [3, 9] by the Deputy Chief Physician or Chief Physician with general or spinal anesthesia. KTP Laser vaporization was performed with a 120-W HPS-KTP laser using a GreenLight HPS System by emitting green light with a wavelength of 532 nm. A 26F continuous-flow cystoscope with 30° lens was used, with the laser set to 80 W initially, 120-W for vaporization, and 30– 40 W for coagulation. The Tm: YAG laser was operated in the continuous-wave mode using a wavelength of 2 um for the procedure. A 26F continuous-flow cystoscope with 30° lens was used, with the laser set to 120-W. The fiber was inserted through the continuous flow laser cystoscope with a separate irrigation channel and the passage of a three-way 20-F silicon catheter after the surgery, followed by continuous irrigation with saline. After the operation, the medical therapy and care that the patients received were identical in both groups.

2.3 Outcome assessment

Perioperative and intra-operative observations were conducted, and the data were recorded, which included the operative time, the energy usage, and the change in the hemoglobin, serum electrolyte level, and the transfusion rate. Post-operative data were also recorded, including catheterization time, hospitalization time, and the peri-operative complications. After periods of 3, 6, 12, and 24 months after the surgery, the patients were followed up with assessments of their Qmax, IPSS, QoL, PVR, and complications. At the 6-, 12-, and 24-month follow-up, the prostate volumes were measured in both groups.

3 Results

The peri-operative data obtained are listed in the Table 2. The operation times in the 120-W PVP and 2 um laser groups were 46.8±14.5 and 49.8±16.5 min, respectively, with no difference between the two groups. To evaluate the blood loss and the possible presence of transurethral resection (TUR) syndrome during the procedure, we assessed the levels of hemoglobin (Hgb) and electrolyte pre-, per-, and post-operation. No significant differences in Hgb and sodium were detected between the two procedures. Moreover, no patients needed transfusion, and no evidence was found of intra-operative fluid absorption that might have led to serum electrolyte unbalance in any of the groups.

Table 2
Peri-operative data in patients with BPH

Index PVP 2 um Laser P Value

Operation time (min) 46.8±14.5 49.8±16.5 ns

Average cost(RMB) 28500 20150 P < 0.05

Catheterization time (d) 1.9±1.3 2.2±1.9 ns

Hemoglobin (g/dL)

Preoperative 13.2±1.6 13.7±1.5 ns

Intra-operative 13.7±1.8 13.6±1.4 ns

Postoperative 13.1±1.2 13.4±1.6 ns

Serum sodium(mmol/L)

Preoperative 142.0±1.9 143.0±2.1 ns

Intra-operative 141.8±1.4 142.1±1.6 ns

Postoperative 142.1±1.8 142.2±1.4 ns

Hospitalization time (d) 3.8±1.2 4.8±1.5 ns

Index	PVP	2 um Laser	P Value
Operation time (min)	46.8±14.5	49.8±16.5	ns
Average cost(RMB)	28500	20150	P < 0.05
Catheterization time (d)	1.9±1.3	2.2±1.9	ns
Hemoglobin (g/dL)
Preoperative	13.2±1.6	13.7±1.5	ns
Intra-operative	13.7±1.8	13.6±1.4	ns
Postoperative	13.1±1.2	13.4±1.6	ns
Serum sodium(mmol/L)
Preoperative	142.0±1.9	143.0±2.1	ns
Intra-operative	141.8±1.4	142.1±1.6	ns
Postoperative	142.1±1.8	142.2±1.4	ns
Hospitalization time (d)	3.8±1.2	4.8±1.5	ns

ns = no significant difference.

After discharge, all patients were followed up for 3, 6, 12, and 24 months. The parameters used and data obtained during the follow-up period are presented in Table 4. Compared to the pre-operation values, significant improvements were obtained in the mean IPSS, QoL scores, Qmax, and PVR at the three-month post-operative visits in both groups. This significant improvement lasted the entire follow-up period, with no significant differences between the two groups. The serum PSA level and prostate volume were followed up in all patients at 6, 12, and 24 months postoperatively. Significant improvements were observed in all patients during the follow-up period, with no differences between the two groups.

Table 3

Intra-operative and post-operative complications

Complications	Incidence (%)		P Value
PVP	2 um Laser
Intra-operative complications
Blood transfusion	0	0
TUR syndrome	0	0
Capsule perforation	0	0
Early post-operative(< 1month) complications
Hematuria (requiring bladder irrigation)	4	6	p > 0.05
Blood transfusion	0	0
Re-catheterization	5	8	p > 0.05
Dysuria	15	35	p < 0.05
Mild	10	19
Moderate	5	16
Severe	0	0
Urge incontinence(transient)	10	24	p < 0.05
Urinary infection	9	16
Long-term complications (> 3Months)
Bladder neck contracture	2	3	p > 0.05
Urethral stricture	4	6	p > 0.05
Reoperation	3	3	p > 0.05
(residual adenoma enlargement)
Incontinence	0	0

Table 4

Qualitative and quantitative variables assessed pre- and postoperatively

Index	Preoperative		Postoperative (months)
	PVP	2um Laser	PVP	2um Laser	PVP	2um Laser	PVP	2um Laser	PVP	2um Laser
			3		6		12		24
	216	198	216	198	216	198	192	168	186	160
IPSS	25.4±5.0	24.9±5.2	9.3±2.4	9.2±2.6	7.08±1.42	7.1±1.26	6.27±1.26	6.34±1.46	6.15±1.22	6.20±1.33
Qol	4.23±0.63	4.26±0.42	0.81±0.76	0.79±0.77	0.79±0.69	0.76±0.84	0.69±0.63	0.71±0.64	0.72±0.63	0.74±0.59
Qmax (mL/s)	7.6±3.4	8.1±2.8	19.3±5.3	19.0±5.5	19.5±4.2	19.4±4.4	19.6±4.4	19.5±4.5	19.6±4.3	9.4±4.7
PVR (mL)	132.3±72.3	125.3±89.9	25.3±12.2	23.1±16.1	14.6±15.2	16.4±12.3	13.9±13.7	14.2±13.4	12.6±12.6	13.2±12.5
Prostate volume (ml)	82±26.3	86±28.1	NM	NM	32.2±11.2	33.1±12.1	31.2±10.5	32.1±9.8	31.1±9.6	32.0±9.3
PSA (ng/mL)	3.42±5.23	3.46±4.98	NM	NM	2.32±0.78	2.40±0.82	2.73±0.47	2.75±0.61	2.72±0.51	2.84±0.59

NM = not measured; other abbreviations as in Table 1. T-test for preoperative and postoperative data; for all conditions, P < 0.05 compared to preoperative values.

Complications were summarized and classified as intra-operative, early post-operative (within the first one month), and long-term (Table 3). No intra-operative complications occurred in the 120-W PVP and 2 um laser group, such as blood transfusion and TUR syndrome. No cases of prostate capsule perforation were observed in any of the patients. In our study, more than one laser fiber was required for five patients in 120-W PVP group. In each of these patients, the prostate volume exceeded 100 mL and necessitated >200 kJ of energy application. In the 2 um laser group, no patients needed the use of the second fiber whether the size of the prostate.

The most common complications were dysuria and urge urine incontinence in the early post-operative period. Dysuria was classified as mild, moderate, and severe. Dysuria not requiring medical treatment was defined as mild (transient), dysuria requiring medical treatment as moderate, and dysuria with bothersome symptoms and requiring medical treatment as severe. The patients with mild or moderate dysuria in the two groups were usually treated successfully with M-acceptor blocker drugs and oral analgesics for several days. None of the patients in both groups had severe dysuria. The aforementioned symptoms of dysuria had disappeared until the wound healed on the average one month after the procedure. The total incidence of dysuria was higher in the 2 um laser group (17.68%) than that in the 120-W PVP group (6.94%).

Four patients in the PVP and six in the 2 um laser group required bladder irrigation due to obvious gross hematuria. The silicon catheters were reserved for 1.9±1.5 days in the 120-W PVP group and for 2.2±1.9 days in the 2 um laser group. After catheter removal, transient urinary retention requiring re-catheterization developed in 13 (5 in 120-W HPS group and 8 in 2 um laser group) who had required a catheter preoperatively. The catheter was removed after 3 days, bladder function training was administered, and successful micturition occurred.

Transient urge incontinence was observed in 10 patients in the 120-W PVP group and in 24 patients in the 2 um laser group. No patient had postoperative incontinence (>3 months) or at the end of the follow-up period. Antibiotics were used for the treatment of patients with urinary tract infections. Only a few patients in both groups required reoperation (Table 3). No other complications related to surgery were observed during the follow-up period in both groups.

4 Discussion

Although TURP is the golden standard for the treatment of BPH, it still can cause adverse events such as bleeding and TUR syndrome. In the past decade, many laser techniques (e.g., GreenLight laser and 2-micrometer continuous laser) have been used for incision, resection, and enucleation of the prostate in a relatively bloodless field [14 , 27– 31]. In our studies, both 120-W GreenLight laser and 2-micrometer continuous laser relieved LUTS with high efficacy and safety with minimal differences in the operation time and blood loss. At the endpoint, from four- to five-fold improvement was observed in the average IPSS in both groups. The Qols and Qmax had improved from three to four folds, and the PVR volume was 80% lower in each of the group as compared with the baseline parameters. Due to the shortcomings of the TURP procedure, we had always used both laser techniques to treat BPH patients in our unit, instead of the conventional TURP procedure. In our previous studies, we have demonstrated that these two techniques are superior to the TURP procedure [8, 9].

Based on the characterization of the KTP laser, 120-W PVP procedure did not induce capsular perforation and did not negatively influence the balance of hemoglobin and electrolytes. Many investigations [32 –35] have shown that 120-W PVP can significantly improve the IPSS, Qmax, and PVR as compared with their respective values obtained in TURP and open prostatectomy. Furthermore, the incidence of reoperation due to urethral stricture and bladder neck contracture for late complications was also similar. Currently, the PVP procedure is used to effectively treat symptomatic BPH of any size, with minimal disturbance in terms of bleeding and imbalance of electrolytes. In our study, the highest volume of a prostate gland was 300 g, with an operation time of 145 minutes, which two fibers were used in the procedure. After the operation, the patient acquired satisfactory urinary outcomes, measured by his IPSS, Qmax, and PVR values. The application of 2 um laser [15] has been also confirmed to be a safe and efficient procedure ensuring faster hemostasis, higher precision, and lower peri-operative morbidity than the transurethral resection of the prostate (TURP), which is similar to the outcomes of the PVP procedure.

Because of the characteristics of the two examined techniques, in our present study, no obvious pre-, intra-, and postoperative changes in the hemoglobin and electrolytes were observed in the 120-W-PVP group; similar results were obtained in the 2 um laser group. This is a major advantage over the TURP procedure. No significant differences were observed between the two groups. Our present findings are similar to those of other reports.

As increased numbers of patients with BPH need medical therapy, this population continues to get older and to have more morbid conditions, including some that necessitate chronic anticoagulation [9]. It is known that with age, cardiac and cerebrovascular events increase, often prompting initiation of chronic anticoagulation therapy. Thus, for these patients, the most common peri-operative preparation is discontinuation of oral anticoagulants, followed by conventional or low-molecular-weight heparin given intravenously or subcutaneously. A previous study showed that TURP was still associated with a blood transfusion rate of 2.0% – 7.1% and an early revision rate of 3.0% – 5.0% [36], which limit it^,s use in this population. However, laser treatment is an effective solution to this problem. Our previous [9] and present study have also demonstrated that both procedures are safe and effective for the treatment of patients with oral anticoagulants. During the peri-operative period, no patients required anticoagulant discontinuation. Meanwhile, none of the procedures increased the risk of blood loss, which also makes them superior to the conventional TURP procedure.

No intra-operative complications (e.g., capsular perforation, blood transfusion, and TUR syndrome) were observed in any of the groups. The TUR syndrome is the most common complication during the TURP procedure, which can induce serum electrolyte unbalance and is dangerous for the BPH patients, especially for high-risk patients and such with cardio-cerebrovascular disease. Our results, in agreement with those of a large number of previous studies [15 , 28], also showed that both procedures safe for BPH patients due to the absence of fluid absorption.

Dysuria and urge incontinence were the most common complications in both groups one month after the operation. The incidence of the two complications was higher in the 2 um laser group than in the 120-W PVP group (Table 4). We speculated that this was related to the eschar of the wound, because we observed obvious carbonization in the 2 um laser group in our study, in spite of the similar penetration depth and solidifying layer of both procedures. Meanwhile, all symptoms significantly spontaneously improved when the prostatic wound healed three months later.

During the follow-up period, we found that the application of both techniques led to a comparable improvement of voiding parameters (IPSS, PVR, and Qmax) and symptoms in the first three months in our study, and these improvements pertained during the follow-up period. Few complications were observed in both groups such as urethral stricture and re-operation incidence. As known, the 2 um laser technique has good efficiency in tissue resection. It is noteworthy that the 120-W PVP group had a similar incidence of re-operation as that of the 2 um laser group, meaning that the former technique effectively removes the targeted prostatic tissue.

The cost of hospitalization is another issue of concern to us. The total expense is lower in the 2 um laser group than in the 120-W PVP group due to the smaller expenditure for surgery and optical fiber. In China, the medical insurance policy is different for each city. The optical fiber of 120-W PVP is not covered by the scope of the medical insurance in our city, and cannot thus be reimbursed. Therefore, it could increase the financial burden of the BPH patients. On the contrary, the 2 um laser is transmitted by ordinary quartz fiber, and the optical fiber can be reused, which lowered the operation cost.

5 Conclusion

Both 120-W-PVP and 2 um laser therapies offer similar effects in relieving the symptoms in BPH patients with high efficacy during a 24-monthfollow-up period. The 120-W PVP procedure provided safer therapy with less post-operative complications such as dysuria and urge incontinence. Nevertheless, the 2 um laser procedure may achieve the same therapeutic effect as 120 W PVP with lower expenses.

Conflict of interest

No.

Research involving human participant and/or animals

Yes.

Informed consent

Yes.

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