Safety and Efficacy of the Potassium-Titanyl-Phosphate Laser and Photoselective Vaporization of the Prostate for Benign Prostatic Hyperplasia

Photoselective Vaporization of the Prostate

RIUS0003(Laserscope)_10-27.qxd 27/10/06 14:53 Page S16 PHOTOSELECTIVE VAPORIZATION OF THE PROSTATE Safety and Efficacy of the Potassium-Titanyl-Phosphate Laser and Photoselective Vaporization of the Prostate for Benign Prostatic Hyperplasia Claus G. Roehrborn, MD Department of Urology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX The currently commercially available 80-W potassium-titanyl-phosphate laser used for photoselective vaporization of the prostate in men with lower urinary tract symptoms and benign prostatic hyperplasia (BPH) is a safe and effective therapeutic alternative for a wide spectrum of prostate sizes and configurations. Efficacy data from multicenter prospective studies, comparative studies against other interventions, and single-center long-term outcomes suggest the efficacy to be at least equivalent to that of transurethral resection of the prostate, with a very good safety profile. New technological developments promise to further enhance the utility of this laser for application in BPH and urology. [Rev Urol. 2006;8(suppl 3):S16-S23] © 2006 MedReviews, LLC Key words: Benign prostatic hyperplasia • Lower urinary tract symptoms • Laser prostatectomy • Potassium-titanyl-phosphate laser • Photoselective vaporization of the prostate enign prostatic hyperplasia (BPH) is the most common benign tumor in men, with the prevalence of this histological condition of the prostate paralleling a man’s age—approximately 50% for men in their fifties and approximately 80% to 90% for men in their eighties and older.1 Approximately 50% of men affected by histological BPH will eventually develop bothersome lower urinary tract symptoms (LUTS), experience interference with activities of daily living and impairment of quality of life (QOL), and many will ultimately seek medical attention in hopes of relief.2-4 The factors that drive health care B S16 VOL. 8 SUPPL. 3 2006 REVIEWS IN UROLOGY RIUS0003(Laserscope)_10-27.qxd 27/10/06 14:53 Page S17 Safety and Efficacy of the KTP Laser and PVP Figure 1. (A,B) Cystoscopic view of benign prostatic hyperplasia gland. (C) Immediate postoperative view after photoselective vaporization of the prostate (PVP). (D) View after 2 years of follow-up. veru, verumontanum; B-N, bladder neck. Reprinted from Malek RS et al,24 with permission from Elsevier. consultation behavior remain unclear, but it is predominantly not the frequency of the symptoms but rather the bother associated with the condition that prompts men to seek advice.5-7 Treatment choices offered range from watchful waiting or active surveillance over medical therapy to minimally invasive therapies and surgical interventions. In the minds of potential patients there is a direct relationship between the invasiveness of the intervention proposed and the risks and safety concerns associated with it, whereas in the minds of health care providers there is a direct relationship between the degree of invasiveness and the efficacy of the intervention. Many patients ultimately choose to initiate treatment with medications and when dissatisfied move to minimally invasive therapies or surgical interventions. The gold standard of surgical therapies to date has been transurethral resection of the prostate (TURP), a time-honored procedure with overall excellent outcomes and a reasonable safety record,8 whereas other alternatives have been wholeheartedly embraced but later discarded with similar enthusiasm. Since its introduction just over a decade ago, laser prostatectomy (LP) has expanded to encompass diverse techniques applied with equally diverse laser wavelengths, each with a specific tissue interaction. There are 3 potential techniques for LP— coagulative LP with the neodymium: YAG (Nd:YAG) laser (visual laser ablation of prostate)9 or diode laser (interstitial laser coagulation)10; cutting (enucleative) LP with the holmium:YAG laser (holmium laser prostate enucleation)11-13; and vaporization LP with the Nd:YAG (transurethral evaporation of prostate), holmium:YAG (holmium laser prostate ablation),14,15 or potassium-titanyl-phosphate (KTP) lasers (Figure 1).16-24 The efficiency of KTP laser in vaporizing tissue is due to selective absorption of photons by hemoglobin and the consequent release of superficially trapped vaporizing thermal energy (see the article by Dr. Te in this issue).25 KTP vaporization LP has been called photoselective vaporization of the prostate (PVP) and was commercialized by Laserscope (San Jose, CA). In original short-term studies of PVP by Malek and colleagues, morbidity was minimal and outcomes were favorable.22,23,26 Following is a review of available efficacy and safety data using the current KTP 80-W laser for PVP in men with LUTS and BPH, excluding other applica- tions and the use of the laser in highrisk populations (which are discussed in the article by Dr. Kaplan in this issue27). Efficacy Data After feasibility studies and successful reports on experiences in canine models,28,29 a 60-W KTP laser was used in 10 men with BPH, and shortterm, 24-hour outcomes were reported by Malek and colleagues.23 The prostate volumes ranged from 22 cm3 to 60 cm3 (mean, 38.4
9.7 cm3). None of the 10 patients had any significant blood loss or any fluid absorption. Foley catheters were removed in less than 24 hours postoperatively. All patients were satisfied with their voiding outcome. The mean peak urinary flow rate (Qmax) increased from 8
1.3 mL/s preoperatively to 19.4
8.4 mL/s (142%; P  .003266) 24 hours postoperatively. Postvoid residual volume (PVR) remained essentially unchanged from preoperative levels, as expected (P  .767423). One patient had urgency, but none had dysuria, hematuria, or incontinence; no patients required recatheterization. This encouraging experience led the investigators to pursue further human studies using the 60-W KTP laser in 55 men with LUTS and BPH.22 Mean prostate volume was 43.6 cm3. No patient had any significant blood loss or fluid absorption, and none required blood transfusion. Foley catheters did not require irrigation and were removed less than 24 hours postoperatively. All patients remained satisfied with voiding outcome, which changed significantly (P  .0001). Mean improvements in the International Prostate Symptom Score (IPSS) at 3, 6, 12, and 24 months were 75%, 79%, 82%, and 82%, respectively. Mean increases in Qmax at the same intervals were 250%, 242%, 255%, and 278%, respectively (Table 1). VOL. 8 SUPPL. 3 2006 REVIEWS IN UROLOGY S17 RIUS0003(Laserscope)_10-27.qxd 27/10/06 14:53 Page S18 Safety and Efficacy of the KTP Laser and PVP continued Table 1 Two-Year Outcome With 60-W KTP Laser Postoperative (P value) Preoperative 3 mo 6 mo 12 mo 55 47 43 36 14 22
5 5.5
2.7 ( .0001) 4.6
2.7 ( .0001) 3.9
2.2 ( .0001) 3.7
1.6 ( .0001) 75 79 82 82 26.5
9.8 ( .0001) 27.0
11.8 ( .0001) 29.1
12.0 ( .0001) No. Patients Mean AUA Symptom Score
SD % Improvement* 2y Mean peak flow
SD (mL/s) % Improvement* 8.0
2.4 27.5
11.0 ( .0001) 250 242 255 278 Postvoid Residual (mL) % Improvement* 154
99 45
43 ( .0001) 69 41
34 ( .0001) 72 53
45 ( .0001) 63 27
31 (0.010) 75 KTP, potassium-titanyl-phosphate; AUA, American Urological Association; IPSS, International Prostate Symptom Score; SD, standard deviation. Reprinted with permission from Malek RS et al.22 *Applies to same patients under evaluation each time. Figure 2. Twelve-month efficacy data from a multicenter trial using the 80-W potassium-titanyl-phosphate laser. AUA-SI, American Urological Association Symptom Index; Qmax, peak urinary flow rate; QOL, quality of life; PVR, postvoid residual; pre-op, preoperative. Data from Te AE et al.30 AUA-SI 25 Mean Qmax (mL/s) 24.0 25 20 20 15 15 10 10 8.0 6.0 5 5.1 4.3 6 mo n  128 12 mo n  119 0 19.5 21.8 22.6 6 mo 12 mo 25.7 26.1 24.8 3 mo 6 mo 12 mo 20.6 7.8 5 0 pre-op n  139 1 mo n  134 3 mo n  132 pre-op 1 mo QOL 3 mo PVR (mL) 5 120 114.3 4.3 100 4 80 3 60 2.1 2 1.5 1.2 1 20 0 0 pre-op S18 35.6 40 1.0 1 mo VOL. 8 SUPPL. 3 2006 3 mo 6 mo REVIEWS IN UROLOGY 12 mo pre-op 1 mo RIUS0003(Laserscope)_10-27.qxd 27/10/06 14:53 Page S19 Safety and Efficacy of the KTP Laser and PVP 30 Total AUA-SI Group I Group II 25 20 15 10 5 0 Baseline (139) 1 y (128) 2 y (83) 3 y (47) 30 Total Qmax (mL兾s) Group I Group II 25 20 15 10 5 0 Baseline (139) 1 y (128) 2 y (83) 3 y (47) Figure 3. AUA-SI score and Qmax changes in all patients and in Groups I and II separately (baseline serum prostatespecific antigen levels  6.0 ng/mL vs  6.0 ng/mL) at 1, 2, and 3 years of follow-up. Numbers in parentheses are total patients (Groups I and II). AUA-SI, American Urological Association Symptom Index; Qmax, peak urinary flow rate. Reprinted with permission from Te AE et al.16 Subsequent to these early trials, Laserscope introduced a higherenergy KTP laser operating at 80 W power output and launched a prospective multicenter study in the United States in 139 men clinically diagnosed with symptomatic bladder outlet obstruction secondary to BPH.30 Patients were evaluated at 1, 3, 6, and 12 months after treatment. Significant improvements in IPSS, QOL score, Qmax, and PVR were noted as early as 1 month after PVP treatment. At 12 months, the mean AUASI score decreased from 24 to 4.3 (P  .0001), and the QOL score decreased from 4.3 to 1.0 (P  .0001), whereas mean Qmax increased from 7.8 to 22.6 mL/s (P  .0001). PVR decreased from 114.3 to 24.8 mL (P  .0001), whereas prostate volume by transrectal ultrasound went from 54.6 cm3 at baseline to 34.4 cm3 (Figure 2). An illuminating subset analysis of 3-year outcomes was recently published by Te colleagues.16 The 139 original patients were divided into 2 subgroups according to baseline serum prostate-specific antigen levels (Group I,  6.0 ng/mL; Group II,  6.0 ng/mL). There was a statistically significant difference in the level of improvement between Groups I and II (P  .05) in AUA-SI and Qmax at 1, 2, and 3 years. The mean (SD) prostate volumes were 48.3 mL (16.7) for Group I (n  87) and 83.1 mL (30.6) for Group II (n  52). The mean percentage improvements in the AUA-SI at 1, 2, and 3 years in Groups I and II, respectively, were 86%, 92%, and 85% and 69%, 74%, and 76%; the corresponding percentage improvements in Qmax were 194%, 185%, and 179% and 124%, 145%, and 139%, respectively (Figure 3). Five-year follow-up data of 94 men are available from the original series published by Malek and colleagues.24 Mean prostate volume was 45 cm3 (range, 13–136 mL). Mean lasing time was 47 minutes (range, 10–99 minutes), and there was minimal blood loss and no evidence of fluid absorption. All 94 men were outpatients, and all but 1 patient became catheter free in less than 24 hours. Baseline IPSS was 22, QOL score was 4.5, Qmax was 7.8 mL/s, and PVR volume was 197 mL. After surgery, percentage changes from baseline in mean values of these parameters reflected significant improvement (P  .0001) at 1, 2, 3, and 5 years, ranging from 83% to 88%, 86% to 90%, 170% to 252%, and 76% to 89%, respectively (Figure 4). Another multicenter trial focused on 64 men with gland sizes greater than 60 cm3 that were detected by transrectal ultrasonograpy.31 Transurethral prostatectomy was performed with an 80-W KTP sidefiring laser system through a 23-F continuous-flow cystoscope with normal saline as the irrigant. The mean preoperative prostate volume was 101
40 cm3. The mean operative time was 123
70 minutes. No transfusions were required. Of the 64 patients, 62 were discharged within 23 hours. The serum sodium level did not change significantly. The IPSS decreased from 18.4 preoperatively to 9.9, 8.6, 7.2, and 6.7 at 1, 3, 6, and 12 months postoperatively, and the Qmax increased from 7.9 mL/s preoperatively to 16.4, 16.2, 20.0, and 18.9 mL/s at 1, 3, 6, and 12 months postoperatively. The PVR volume also decreased from 189 mL VOL. 8 SUPPL. 3 2006 REVIEWS IN UROLOGY S19 RIUS0003(Laserscope)_10-27.qxd 27/10/06 14:53 Page S20 Safety and Efficacy of the KTP Laser and PVP continued AUA Symptom Score Mean Qmax (mL/s) 25 30 26.4 22.0 27.1 26.6 25 20 23.6 22.2 20 15 15 10 10 4.6 5 3.8 3.7 3.4 2.6 12 mo n  66 24 mo n  48 36 mo n  32 60 mo n  14 0 7.8 5 0 pre-op n  94 6 mo n  76 pre-op 6 mo QOL Score 5 12 mo 24 mo 36 mo 60 mo 18.0 23.6 25.0 24 mo 36 mo 60 mo PVR (mL) 200 4.5 4 197.0 150 3 100 2 50 1 0.3 0.4 6 mo 12 mo 0.6 0.4 0 pre-op 24 mo 36 mo 0.1 60 mo 37.0 43.0 0 pre-op 6 mo 12 mo Figure 4. Long-term 5-year outcome with potassium-titanyl-phosphate laser for photoselective vaporization of the prostate in 94 patients. AUA, American Urological Association; Qmax, peak urinary flow rate; QOL, quality of life; PVR, postvoid residual; pre-op, preoperative. Data from Malek RS et al.24 preoperatively to 78, 78, 67, and 109 mL at 1, 3, 6, and 12 months postoperatively, respectively. These data suggest that adequate efficacy can be achieved in men with large glands (ie, glands that usually are not suitable for standard TURP, according to the recommendation to limit this technique to those cases for which resection time is  60 minutes and resected weight is  60 g). In addition to the studies discussed above, there are several other studies published of men with large glands,19 men taking anticoagulation medications,18 and comparisons of the KTP laser technique with standard surgical interventions,32,33 generally with very favorable outcomes. S20 VOL. 8 SUPPL. 3 2006 Safety Data In general, the KTP laser has been found to be a very safe therapeutic alternative in the treatment of men with LUTS and BPH. Because of the use of normal saline as an irrigant, TURP syndrome does not occur, and in fact, many investigators reported no changes or insignificant changes in serum sodium from before to after the procedure. It is often called the “bloodless TURP,” and changes in hematocrit are clinically and, in most cases, statistically insignificant and result from hemodilution when they do occur. Transfusion rates are essentially zero, and readmissions for clot retention have been extremely rare. In the original series, Malek and col- REVIEWS IN UROLOGY leagues reported transient dysuria in 7%, bladder neck contracture in 2%, and delayed hematuria in 4% of 55 patients.22 None of the patients required recatheterization or reoperation, or had incontinence or newly developed impotence. Of the sexually active patients, 15% and 9% had retrograde ejaculation at 1 and 2 years, respectively. In the long-term followup, similarly low adverse event rates were reported for 94 patients as follows: transient dysuria (6%), delayed hematuria (3%), bladder neck contracture (2%), and 2-day retention (1%). No patient had incontinence or newly developed impotence, but up to 26% of the sexually active men experienced retrograde ejaculation.24 In RIUS0003(Laserscope)_10-27.qxd 27/10/06 14:53 Page S21 Safety and Efficacy of the KTP Laser and PVP Prolonged Dysuria ( 10 d) 9.4 6 Transient ( 10 d) Hematuria 8.6 3 Transient Urinary Urge Incontinence 6.5 0 Urinary Tract Infection 2.2 2 Urinary Retention Requiring Recatheterization 5 1 strictures of the urethra, and infections were reported in up to 2.2% of patients (Table 2).24,30 Total incontinence is extremely rare and new-onset impotence very unlikely because of the favorably limited penetration of the KTP laser into the tissues and through the capsule. However, as expected for any procedure that effectively vaporizes the bladder neck, retrograde ejaculation is noted in a substantial number of men. Bladder Neck Contracture 1.4 2 Conclusions Urethral Stricture 0.7 0 Epididymitis 0.7 0 The currently commercially available 80-W KTP laser for PVP in men with LUTS and BPH is a safe and effective therapeutic alternative for a wide spectrum of prostate sizes and configurations. Efficacy data from multicenter prospective studies, comparative studies against other interventions, and single-center long-term outcomes suggest the efficacy to be equivalent to TURP, with a very good safety profile (Table 3). Table 2 Compilation of Adverse Events Reported in US Multicenter and Long-Term Follow-up Study Te AE et al30 (%) Complications Impotence 0 Retreatment at 1 y 0 the multicenter trial of 139 men, Te and colleagues reported on transient hematuria, dysuria, and urinary retention in 12 (8.6%), 13 (9.3%), and 7 Malek RS et al24 (%) 0 None reported (5%) of patients, respectively.30 Dysuria, urgency, and mild hematuria were reported in up to 9.4% of patients, and bladder neck contractures, Table 3 Comparison of Efficacy (IPSS and Q max ) of Surgical Interventions Versus KTP/PVP Prostatectomy in Selected Series from the Literature IPSS Modality Qmax (mL/s) 3-9 mo 10-16 mo Long Term 3-9 mo 10-16 mo Long Term TURP 14.7 14.8 13.6 10.5 10.8 8.1 Holmium Resection/Enucleation 17.8 17.9 12.2 11.0 TU Laser Coagulation 17.0 20.2 8.5 11.0 TUIP 11.9 15.2 10.8 8.7 7.8 6.3 TU Electrovaporization 11.5 15.8 19.3 10.5 12.5 12.5 15.5 11.5 14.0 PVP28 18.0 9.7 12.8 14.8 PVP vs TURP32 12.9 PVP in Large Glands31 11.2 11.7 12.1 11.0 -17.4 18.2 18.6 19.3 18.4 10.1 Open Prostatectomy 24 PVP Long-Term Study 3.3 11.2 18.6 15.8 IPSS, International Prostate Symptom Score; Qmax, peak urinary flow rate; KTP, potassium-titanyl-phosphate; PVP, photoselective vaporization of the prostate; TURP, transurethral resection of the prostate; TU, transurethral; TUIP, transurethral incision of the prostate. Data from the AUA Practice Guidelines Committee,8 Te AE et al,30 Bachmann et al,32 Sandhu et al,31 and Malek et al.24 VOL. 8 SUPPL. 3 2006 REVIEWS IN UROLOGY S21 RIUS0003(Laserscope)_10-27.qxd 27/10/06 14:53 Page S22 Safety and Efficacy of the KTP Laser and PVP continued Recently, Laserscope was acquired by American Medical System (AMS; Minnetonka, MN) during the release of the new, higher-powered, 120-W system for PVP in BPH (GreenLight HPS®). If safety can be maintained, it is likely that this modification will further shorten the operative time for the procedure with equivalent efficacy data. The Laserscope acquisition filled a substantial gap in the AMS BPH portfolio in the ablation category. The combination of the GreenLight PV® and high-performance system technologies with the urology relationships AMS has created throughout the years has formed a powerful new enterprise that can address nearly all BPH patients with a family of solutions, including TherMatrx® and UroLume®, as well as GreenLight. 3. 4. 5. 6. 7. 8. 9. 10. References 1. 11. Berry SJ, Coffey DS, Walsh PC, Ewing LL. The development of human benign prostatic hyperplasia with age. J Urol. 1984;132:474-479. Girman CJ. Population-based studies of the epidemiology of benign prostatic hyperplasia. Br J Urol. 1998;82 (suppl 1):34-43. 2. 12. Girman CJ, Epstein RS, Jacobsen SJ, et al. Natural history of prostatism: impact of urinary symptoms on quality of life in 2115 randomly selected community men. Urology. 1994;44:825831. Girman CJ, Jacobsen SJ, Tsukamoto T, et al. Health-related quality of life associated with lower urinary tract symptoms in four countries. Urology. 1998;51:428-436. Berges RR, Pientka L, Hofner K, et al. Male lower urinary tract symptoms and related health care seeking in Germany. Eur Urol. 2001;39:682-687. Jacobsen SJ, Girman CJ, Guess HA, et al. Natural history of prostatism: factors associated with discordance between frequency and bother of urinary symptoms. Urology. 1993;42:663-671. Roberts RO, Rhodes T, Panser LA, et al. Natural history of prostatism: worry and embarrassment from urinary symptoms and health care-seeking behavior. Urology. 1994;43:621-628. AUA Practice Guidelines Committee. AUA guideline on management of benign prostatic hyperplasia (2003). Chapter 1: diagnosis and treatment recommendations. J Urol. 2003;170(2 pt 1):530-547. Hoffman RM, MacDonald R, Slaton JW, Wilt TJ. Laser prostatectomy versus transurethral resection for treating benign prostatic obstruction: a systematic review. J Urol. 2003;169:210-215. Muschter R, Whitfield H. Interstitial laser therapy of benign prostatic hyperplasia. Eur Urol. 1999;35:147-154. Kuo RL, Kim SC, Lingeman JE, et al. Holmium laser enucleation of prostate (HoLEP): the Methodist Hospital experience with greater than 75 gram enucleations. J Urol. 2003;170:149152. Hochreiter WW, Thalmann GN, Burkhard FC, Studer UE. Holmium laser enucleation of the 13. 14. 15. 16. 17. 18. 19. 20. prostate combined with electrocautery resection: the mushroom technique. J Urol. 2002;168(4 pt 1):1470-1474. Hurle R, Vavassori I, Piccinelli A, et al. Holmium laser enucleation of the prostate combined with mechanical morcellation in 155 patients with benign prostatic hyperplasia. Urology. 2002;60: 449-453. Tan AH, Gilling PJ, Kennett KM, et al. Long-term results of high-power holmium laser vaporization (ablation) of the prostate. BJU Int. 2003; 92:707-709. Mottet N, Anidjar M, Bourdon O, et al. Randomized comparison of transurethral electroresection and holmium: YAG laser vaporization for symptomatic benign prostatic hyperplasia. J Endourol. 1999;13:127-130. Te AE, Malloy TR, Stein BS, et al. Impact of prostate-specific antigen level and prostate volume as predictors of efficacy in photoselective vaporization prostatectomy: analysis and results of an ongoing prospective multicentre study at 3 years. BJU Int. 2006;97:1229-1233. Sarica K, Alkan E, Luleci H, Tasci AI. Photoselective vaporization of the enlarged prostate with KTP laser: long-term results in 240 patients. J Endourol. 2005;19:1199-1202. Sandhu JS, Ng CK, Gonzalez RR, et al. Photoselective laser vaporization prostatectomy in men receiving anticoagulants. J Endourol. 2005;19: 1196-1198. Bachmann A, Ruszat R, Wyler S, et al. Photoselective vaporization of the prostate: the Basel experience after 108 procedures. Eur Urol. 2005; 47:798-804. Sulser T, Reich O, Wyler S, et al. Photoselective KTP laser vaporization of the prostate: first experiences with 65 procedures. J Endourol. 2004; 18:976-981. Main Points • Since its introduction just over a decade ago, laser prostatectomy has expanded to encompass diverse techniques applied with equally diverse laser wavelengths, each with a specific tissue interaction. • The efficiency of the potassium-titanyl-phosphate (KTP) laser in vaporizing tissue is due to selective absorption of photons by hemoglobin and the consequent release of superficially trapped vaporizing thermal energy. Therefore, KTP vaporization laser prostatectomy has been called photoselective vaporization of the prostate (PVP). • Subsequent to successful early trials with the 60-W KTP laser, Laserscope introduced a higher-energy KTP laser operating at 80-W power output. Recent long-term trials of patients with benign prostatic hyperplasia (BPH) have shown significant improvements in efficacy parameters after KTP laser treatment, including International Prostate Symptom Score, peak urine flow rate, and postvoid residual volume. • Data from a multicenter trial of 64 men with gland sizes over 60 cm3 have suggested that adequate efficacy can be achieved with laser prostatectomy in men with large glands (ie, glands that are usually not suitable for standard transurethral resection of the prostate). • In general, the KTP laser has been found to be a safe and effective therapeutic alternative in the treatment of men with lower urinary tract symptoms and BPH, suitable for a wide spectrum of prostate sizes and configurations. In several clinical trials, low adverse event rates have been reported after PVP; total incontinence is extremely rare and new-onset impotence unlikely. • The release of a new, higher powered 110-W KTP system for PVP in BPH is expected in the near future; if safety can be maintained, it is likely that this modification will further shorten the operative time for the laser procedure with equivalent efficacy data. S22 VOL. 8 SUPPL. 3 2006 REVIEWS IN UROLOGY RIUS0003(Laserscope)_10-27.qxd 27/10/06 14:53 Page S23 Safety and Efficacy of the KTP Laser and PVP 21. Hai MA, Malek RS. Photoselective vaporization of the prostate: initial experience with a new 80 W KTP laser for the treatment of benign prostatic hyperplasia. J Endourol. 2003;17:93-96. 22. Malek RS, Kuntzman RS, Barrett DM. High power potassium-titanyl-phosphate laser vaporization prostatectomy. J Urol. 2000;163:17301733. 23. Malek RS, Barrett DM, Kuntzman RS. Highpower potassium-titanyl-phosphate (KTP/532) laser vaporization prostatectomy: 24 hours later. Urology. 1998;51:254-256. 24. Malek RS, Kuntzman RS, Barrett DM. Photoselective potassium-titanyl-phosphate laser vaporization of the benign obstructive prostate: observations on long-term outcomes. J Urol. 2005;174(4 pt 1):1344-1348. 25. Te AE. The next generation in laser treatments and the role of the GreenLight High-Performance 26. 27. 28. 29. 30. System laser. J Urol. 2006;8(suppl 3):S24-S30. Malek RS, Barrett DM, Dilworth JP. Visual laser ablation of the prostate: a preliminary report. Mayo Clin Proc. 1995;70:28-32. Kaplan SA. Expanding the role of photoselective vaporization of the prostate. Rev Urol. 2006; 8(suppl 3):S3-S8. Kuntzman RS, Malek RS, Barrett DM, Bostwick DG. Potassium-titanyl-phosphate laser vaporization of the prostate: a comparative functional and pathologic study in canines. Urology. 1996;48:575-583. Kuntzman RS, Malek RS, Barrett DM, Bostwick DG. High-power (60-watt) potassium-titanylphosphate laser vaporization prostatectomy in living canines and in human and canine cadavers. Urology. 1997;49:703-708. Te AE, Malloy TR, Stein BS, et al. Photoselective vaporization of the prostate for the treatment of 31. 32. 33. benign prostatic hyperplasia: 12-month results from the first United States multicenter prospective trial. J Urol. 2004;172(4 pt 1):1404-1408. Sandhu JS, Ng C, Vanderbrink BA, et al. Highpower potassium-titanyl-phosphate photoselective laser vaporization of prostate for treatment of benign prostatic hyperplasia in men with large prostates. Urology. 2004;64:1155-1159. Bachmann A, Schurch L, Ruszat R, et al. Photoselective vaporization (PVP) versus transurethral resection of the prostate (TURP): a prospective bicentre study of perioperative morbidity and early functional outcome. Eur Urol. 2005;48:965-971; discussion 972. Reich O, Bachmann A, Schneede P, Zaak D, et al. Experimental comparison of high power (80 W) potassium titanyl phosphate laser vaporization and transurethral resection of the prostate. J Urol. 2004;171(6 pt 1):2502-2504. VOL. 8 SUPPL. 3 2006 REVIEWS IN UROLOGY S23