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Lasers in the treatment of benign prostatic hyperplasia
LASERS IN THE TREATMENT OF BENIGN PROSTATIC HYPERPLASIA GLENN S. GERBER, M.D. From the Section of Urology, Department of Surgery, University of Chicago Pritzker School of Medicine, Chicago, Illinois
Transurethral resection of the prostate (TURP) has been the gold standard in the treatment of benign prostatic hyperplasia (BPH) for many years. Recently, a number of alternative treatments have been investigated and have gained acceptance to varying degrees. These include the use of oral medications, such as 5-alpha-reductase inhibitors and alpha,-adrenergic antagonists, as well as minimally invasive surgical approaches, such as hyperthermia and the use of laser energy to ablate the prostate. Although the efficacy of TURP in relieving bladder outlet obstruction secondary to prostatic enlargement has been clearly demonstrated,’ the primary reason for the growing popularity of alternative therapeutic approaches to BPH is the potential reduction in morbidity and cost associated with these techniques. The use of laser energy to treat diseases of the prostate was first reported in 1984 by Sander and Beisland.’ These authors treated 16 men with clinically localized prostate cancer with laser energy delivered transurethrally. Short-term results indicated no serious complications and good disease control. In 1985, Shanberg et a1.3 used laser energy to perform transurethral incisions of the prostate (TUIP) in men with symptomatic BPH. Although the use of laser energy adds little to the overall effectiveness of TUIP compared with standard incisional techniques, this was the first step in the rapid proliferation of reports concerning lasers and the treatment of BPH. The technique of laser prostatectomy continues to evolve. This article will review the principles of laser energy as applied to the treatment of BPH, as well as currently available technology Finally, the published results of laser prostatectomy will be reviewed in an attempt to place this procedure in its proper perspective. Submitted: June 9, 1994, accepted (with revisions): September 12,1994
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BACKGROUND The term “laser prostatectomy” encompasses a wide variety of procedures performed using a broad range of techniques and technology. The results achieved with one type of laser energy delivered in a particular fashion may have no bearing on the tissue effects that may be seen using other lasers and modes of delivery. Therefore, the careful reader of literature concerning laser treatment of BPH must pay close attention to technical details regarding each individual procedure. Essentially, the effects of laser energy on prostate tissue are based on thermal action.4 With acute heating up to 6O”C, there is no significant change in the appearance or long-term effect on the tissue. Between 60°C and lOO”C, coagulation necrosis occurs as a result of protein denaturation. The tissue blanches and turns white with resultant slough over several days to weeks. Finally, vaporization of prostate tissue occurs with heating to greater than 100°C. This latter form of treatment leads to immediate ablation of prostate tissue in contrast to the delayed slough seen with coagulative necrosis. The neodymium: yttrium-aluminum - garnet (Nd:YAG) laser has been the most commonly used laser in the treatment of BPH. The Nd:YAG laser emits a wavelength of 1064 nm, which is poorly absorbed by water and hemoglobin, facilitating its endoscopic use in a fluid medium. In addition, the energy is readily transmitted by fiber, and tissue penetration up to 4 to 5 mm may be achieved. However, the limits of penetration of laser energy are not necessarily equivalent to the depth of penetration of significant laser effect.4 This is due to a variety of factors, including lateral diffusion and backscatter of laser energy The magnitude of these effects is based on individual tissue characteristics, but the end result is a proportionate decrease in temperature rise and tissue effect with increasing tissue penetration.4
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The use of lasers in the treatment of BPH may be broadly divided into two categories based on the form of energy delivery: contact and noncontact. In the former case, the primary effect on the prostate is tissue vaporization whereas noncontact laser treatment primarily relies on coagulation necrosis. The main advantage of contact laser treatment of the prostate is immediate relief of obstruction. However, vaporization may be slow and direct contact may lead to rapid damage to the fiber tips, necessitating the use of multiple fibers. The treatment of large prostates may be particularly difficult and time consuming with contact techniques. Initially noncontact laser coagulation was generally unsuccessful in relieving prostate obstruction mainly owing to the use of end fire probes. With this technique, it was very difficult to orient the fiber in proper relationship to the tissue in order to maximize the laser effects. The introduction of right angle delivery systems (side fire) largely overcame this shortcoming and noncontact laser treatment of the prostate has increased rapidly in popularity The advantages of this technique include the speed and ease with which the procedure may be performed, as well as the minimal bleeding that occurs. The primary disadvantage of noncontact treatment is the resultant delayed tissue slough that generally necessitates the use of an indwelling urethral catheter or suprapubic tube for several days to weeks. TRANSURETHRAL ULTRASOUND-GUIDED LASER-INDUCED PROSTATECTOMY The transurethral ultrasound-guided laserinduced prostatectomy (TULIP) system consists of a 20 F probe that is placed transurethrally into the prostatic urethra. Incorporated within this probe is a right angle laser window and an ultrasound transducer. The laser window, through which the laser light is delivered to the tissue, is located between the two halves of the split transducer, which produces a sector scan of the adjacent prostate anatomy The laser energy is delivered into the tissue at a right angle accompanied by simultaneous real-time ultrasound imaging. The entire probe is contained within a 36 F or 48 F balloon (sleeve) filled with sterile water. This balloon allows for optimal ultrasound imaging and also compresses the prostate lobes to allow for consistent spacing between the laser and its target tissue. This spacing prevents charring of the laser fiber and improves penetration by the laser energy.5,6 The balloon is filled to 2 atmospheres of pressure and early work with the TULIP system in the canine model showed no significant prostatic urethral dilation associated
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with this technique, suggesting that beneficial results were related solely to the laser effects.’ The TULIP procedure is generally performed using either regional or general anesthesia.5 Cystoscopy is performed initially followed by positioning of the TULIP probe. The balloon is inflated to 2 atmospheres and the entire prostate is imaged sonographically. The TULIP system is then connected to the Nd:YAG laser, which is set at 30 to 40 W. The prostate is treated by drawing the probe from the bladder neck to a position just proximal to the prostatic apex. This is done at a pull rate of 1 mm/s using continuous sonographic visualization of the prostate. Approximately 8 to 10 passes at varying positions within the prostatic urethra are made based on the sonographic appearance. Cystoscopy is performed after completion of the TULIP procedure to confirm that appropriate laser treatment has occurred. This is demonstrated by the appearance of multiple blanched lines at the treated sites. In most cases, a suprapubic catheter is placed for postoperative bladder drainage. Results of the TULIP procedure have been reported by a number of investigators.5,7-15 The largest study has been conducted by the National Human Cooperative Study group in the United States.5,10,11,13 In the first 150 men treated at 10 different institutions, the mean Boyarsky symptom score decreased from a preoperative level of 18.8 to 6.1 and the mean peak urinary flow rate increased from 6.7 mL/s to a post-treatment rate of 11.9 mL/s at 6 months follow-up.5 These improvements in symptom score and flow rate were similar in a subgroup of 40 men with follow-up of 12 and 24 months.13 The mean estimated blood loss was 17 cc in the 150 treated patients, with no patient requiring a blood transfusion. The average hospital stay was 1.7 days. Short-term complications included lower urinary tract irritative symptoms, which often resolved by 2 to 3 weeks after the procedure, and the need for prolonged bladder drainage. Suprapubic catheters remained in place for an average of 2 weeks, although 20% of the patients required replacement of the catheter due to an inability to void, adequately following suprapubit tube removal. Other authors have found that patients undergoing the TULIP procedure require bladder drainage for much longer periods of time, particulary those with urinary retention preoperatively l2 Using a postvoid residual (PVR) urine value of less than 100 cc as the criteria for suprapubic tube removal, Schulze et aI.” reported that patients required bladder drainage for a mean of 34 days. Long-term complications noted with the TULIP procedure include impotence (4%), urethral
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TABLE I. System
Manufacturer
Lateralase* Urolase ADD’Stat UltraLine Sidefire Prolase II
Trimedyne Bard Laserscope Lasersonics Myriadlase Cytocare
Right angle laser fiber delivery systems * Incident
Delivery
Angle
Arc of Divergence
Fiber Diameter
Reflective Reflective Refractive Refractive Reflective Refractive
90” 90” 70” 80” 105” 45”
30” 30” 20” 20” 15” 35”
600pm 600km 600pm 600k.m 600pm 2mm
Energy
Reflector Diameter 7.5 F 7.5 F NIA N/A 6.3 F N/A
List+ Price ($1 N/A 840 695 595 650 700
*Fiberslistedare thosewith reportedresults ‘EffectiveMay,1994. ‘Notpresentlycommerciallyavailable.
stricture or bladder neck contracture (5%), incontinence (3.8%) and retrograde ejaculation (5.4%).13 Similar results have been reported by other groups.8~9~12~14J5 Schulre et al. performed a randomized study comparing TULIP with TURP in 40 patients. Improvements in peak urinary flow rate, residual urine, and symptom score were similar in the two groups at 6 months follow-up, with slightly better results in all three categories in those treated by TURF! In general, patients treated by the TULIP procedure required a significantly longer period of time to attain improved voiding. This lack of short-term improvement is consistent with the mechanism of tissue slough over several weeks that occurs with the TULIP technique. Overall, the TULIP procedure has been well studied in large groups of patients.* Early results indicate that improvements in symptom score closely approximate those seen with TURP while increases in flow rate are significant but inferior to those achieved with standard prostatic electroresection. The primary advantage of the TULIP procedure is the absence of significant bleeding that allows patients to be treated on an outpatient basis in many cases. However, prolonged catheterization of several days to weeks is usually needed and patients do not have improvement in their symptoms for 1 or 2 months after the procedure. In addition, significant irritative symptoms secondary to local edema and tissue response may persist for many weeks. Nevertheless, by 3 months following the TULIP procedure, the majority of patients will have significant improvement in their symptoms, flow rate, or both, and these results appear to be durable at 1 to 2 years.6 NONCONTACT VISUAL LASER PROSTATECTOMY A variety of right angle delivery systems that are used under direct cystoscopic vision have been
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investigated. This procedure has been called “visual laser ablation of the prostate” (VLAP). Although there are differences among the increasing number of available laser fibers (Table I), the basic principles of energy delivery to prostate tissue are similar. The Nd:YAG laser energy is passed along a 600 to 1000 km fiber and is then reflected or refracted at a 45” to 105” angle into the tissue. The energy delivery occurs over a 15’ to 35” arc of divergence as the fiber tip is maintained approximately 1 mm from the prostate. Reflective systems utilize a 6 to 7.5 F gold or gold-plated alloy dish reflector tip that is glued to the end of the fiber. Tissue effects are largely based on the power setting (40 to 80 W in most cases>, duration of treatment, and the distance maintained between the dish reflector or fiber tip and the prostate (1 mm). In addition, the number of treatment sites also greatly affects the overall result. In most cases, a four quadrant series of laser treatments (2, 4, 8, and 10 o’clock positions) are used in men with prostatic urethral lengths of 2.5 to 4 cm or less. In those patients with a longer prostatic urethra, two series of four quadrant laser burns spaced at equal intervals from the bladder neck to the verumontanum are most frequently used. Alternatively, total tissue ablation with treatment of all visible adenoma of the prostate may be utilized. This type of treatment generally leads to the delivery of much larger amounts of energy, and it has been suggested that total ablation techniques may allow for improved long-term results.ls Further study will be necessary to determine the most appropriate VLAP technique. The potential variability in VLAP treatment techniques may lead to significant differences in laser effects and treatment results among surgeons. This is in contradistinction to the TULIP system in which ,use of a water-filled balloon surrounding the laser fiber allows for constant spacing and more uniform tissue effects and results.
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TABLE II.
Results of noncontact right angle endoscopic controlled Nd:YAG laser prostatectomy
Reference Kabalin16 Norris et al. I7 Shanberg et al. I8 Costello et a/. I9 Anson et a/.*O Gill et a/.*’ Kreutzer et a/.** Krautschick et a/.23 Buckley et a/.24 Dixon et a/.25 Kabalin26 Leach et a/.*’ Leach et al.28
Peak Flow (cc/s) Pre* Post *
Laser System
No. Patients
Urolase Urolase ADD, Urolase Prolase Lateralase Lateralase Sidefire Prolase II Urolase UltraLine Urolase Urolase Urolase Urolase Urolase
13 108 25+ 25$ 17
8.5 7.6 5.7 6.5 5
12 50 22 39 77 20 62 50 28
11 10.5 8.8 7.3 9.9 9.2 7.7 7.4 8.1
Symptom
Score
Length of Follow-up (mo.)
Pre
Post
20.5 12 13.5 14.5 9
20.9 22.3 26.5 25.6 15
4.6 12.6 7.8 5.2 4
6 3-6 4-16 4-16 l-l.5
13 16.6 10.7 19.3 17.5 14.1 15.8 16 13.0
23 18.9 NIA 32 19 16.5 20.9 21 21
9 9.7 NIA 5 6 11.9 9.9 8.3 9.4
3 3 6 3 6 6 6 12 6
*pre = pretreatment; Post = post-treatment. ‘Patients treated by 4 OT8 quadrant technique. ‘Patients treated by total tissue ablation technique.
A large number of investigators have reported results using the VLAP technique (Table II).16-31 In general, these studies indicate significant improvements in peak flow rate and symptom score with 3 to 12 months of follow-up. Randomized studies comparing VLAP and TURP have also been reported.16~24~25~30Th ese also indicate significant objective and subjective improvements with the laser technique, although the results are not as good as those achieved with TURP in some cases. Buckley et a1.24 noted that 1 year following TURP or VLAP using the Urolase fiber improvements in symptom score and PVR were similar but flow rate was better in the TURP group. Dixon et ~1.~~ also compared these procedures and found that symptom score reduction was superior with TURP at 12 months follow-up. In addition, improvements in PVR and flow rate were also better with TURP but were not statistically significant. Most importantly, 41% of men treated by VLAP were dissatisfied with the results of the procedure or had required repeat surgery by 1 year compared with 11% in the TURP group. In contrast, Kabalin16 noted equivalent efficacy at 6 months in 25 men randomized to TURP and VLAP as assessed by symptom score, flow rate, and PVR. The complications of VLAP include lower urinary tract irritative symptoms that may not resolve for 1 to 2 months. In addition, postoperative bladder drainage is usually necessary for several days, with a small percentage of patients requiring a catheter for up to several weeks. Increased duration of catheterization is strongly associated with
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pretreatment urinary retention.17 Finally, changes in sexual function have also been noted following VLAI? Leach et a1.27 reported a loss of potency in 5 of 117 (4.3%) men treated with the Urolase fiber2’ and the incidence of retrograde ejaculation is approximately 5% to 1O%.‘6,27 One of the most important advantages of the VLAP procedure is the lack of significant bleeding associated with the technique. Transfusions have been unnecessary in large groups of treated patients and in most cases the procedure can be performed on an outpatient basis without the need for catheter irrigation.17 In addition, patients can be safely treated while fully anticoagulated.32,33 In comparison with the TULIP technique, the VLAP procedure appears to be subject to greater variability in results. This is largely due to the use of a large variety of right angle delivery systems as well as significant differences in surgical technique used by individual treating physicians. As emphasized earlier, results achieved with VLAP may not be reproducible using alternative laser fibers and treatment strategies. CONTACT LASER VAPORIZATION OF THE PROSTATE Although a large number of researchers have investigated and published results using a variety of noncontact right angle delivery systems, information regarding the use of contact laser treatment of men with BPH is limited. Contact vaporization is performed most commonly using the Nd:YAG laser and conventional fibers. A contact tip of
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fused silica quartz or synthetic sapphire is connected to the fiber, and treatment is performed by placing this tip directly against the prostate. The laser energy is rapidly converted to thermal energy as it enters the tip, which produces intense heat and immediate removal of tissue.34 Initial attempts at direct vaporization of prostate tissue were largely unsuccessful due to the slow and tedious nature of the procedure as well as rapid fiber tip destruction. 6 Recently, several investigators have used larger (3 to 5 mm), more durable fiber tips that increase energy delivery and may make it possible to vaporize obstructing adenomatous tissue more efficiently.35-37 There is significant theoretic advantage to contact vaporization of the prostate compared with noncontact coagulation necrosis. At the completion of a successful treatment using contact techniques, a large open cavity is created in the prostatic fossa leading to immediate relief of obstruction. This allows for early catheter removal and rapid improvement in obstructive symptoms. In addition, it appears that the lower urinary tract irritative symptoms that often occur after right angle coagulation of the prostate are much less common with contact vaporization. 36 The primary disadvantages of direct contact treatment are the inability to ablate large prostates effectively and less effective hemostasis compared with noncontact procedures. Published results of contact laser vaporization of the prostate are limited. Watson et ~1.~~performed an initial pilot study in 60 men using the Nd:YAG laser and fused silica tips of up to 3.5 to 5.0 mm in diameter. Limited results indicated significant improvements in flow rate and symptom score with short-term follow-up. Other authors have reported minimal bleeding with contact treatment in small groups of patients and believe that prostates up to 50 cc in volume may be successfully treated. 35-37The continued development and refinement of contact probes and delivery systems are likely to improve the efficacy of contact vaporization of the prostate. If these technical advances lead to efficient and effective removal of large amounts of prostate tissue, the benefits of immediate symptom improvement and early catheter removal may allow contact vaporization to supersede noncontact right angle techniques as the preferred method of laser prostatectomy. INTERSTITIAL LASER TREATMENT OF THE PROSTATE An alternative method of laser prostatectomy that has been investigated involves the interstitial placement of laser fibers directly into the prostate UROLOGY@ / FEBRUARY 1995 I VOLUME45, NUMBER2
parenchyma.38-44 The fibers are fitted with special diffuser tips and are most commonly inserted through needle guides that are placed percutaneously through the perineum or directly into the prostate via a cystoscope. Fiber placement and subsequent treatment using the Nd:YAG laser are continuously monitored using transrectal ultrasonography. Interstitial laser treatment of the prostate allows for preservation of the urothelium, thus preventing tissue slough leading to potentially less irritative symptoms than are seen with other laser techniques. Interstitial laser therapy in canine prostates leads to the formation of extensive zones of coagulation necrosis surrounding the site of laser treatment.41,43,44The size of these zones correlates well with the power delivered and over the course of 7 weeks following the treatment, scars are formed with cellular degeneration and necrosis and associated tissue shrinkage. 43 A small number of studies using interstitial laser treatment in men with BPH have been reported.38-40,43 Muschter et a1.38 treated 184 patients over a 2-year period. Six months follow-up was available in 134 (73%) of these men, with significant improvements in the mean symptom score, flow rate, and postvoid residual urine noted. Ten patients underwent TURP due to persistent obstruction. Other studies have also demonstrated objective and subjective improvement in smaller groups of patients with 2 to 6 months of follow-up.39,40,43In general, bleeding was absent or minimal, short periods of catheterization were needed, and sexual function, including antegrade ejaculation, was preserved. Interstitial laser treatment of the prostate is a promising technique that will require more rigorous testing with longer follow-up before its true value and efficacy can be determined. DOSIMETRY AND TECHNICAL CONSIDERATIONS Presently, the greatest experience with lasers in the treatment of BPH has been with right angle noncontact techniques performed under direct vision (VLAP) or with ultrasound guidance (TULIP). Although good results have been reported using a variety of laser systems and techniques, there is limited information available concerning the most effective power setting, duration of energy delivery, and the resultant effects on prostate tissue. Most of the early work with the Urolase system consisted of treatment of the lateral lobes with 60 W of power for 60 seconds followed by the same or lesser energy delivery to the roof and floor of the prostatic fossa. 16,17,28 However, studies in 197
canine and human prostates have suggested that peak tissue effects are achieved with lower power settings (15 to 40 W) used for longer intervals (90 seconds). 45-48Kabalin and Gi1148 used the Urolase fiber in 29 canine prostates at variable power settings and treatment durations. Peak tissue ablation occured at 40 W with up to 21 mm tissue penetration and a mean depth of tissue destruction that was more than 30% greater than that seen with a power setting of 60 W. Similarly, the mean volume of tissue ablation was more than 60% greater at 40 W than at 60 W. In addition, using a constant power setting of 40 W, tissue effects were noted to rise steadily and then plateau beyond 90 seconds. Finally, discontinuous energy delivery significantly decreased the observed tissue effects compared with a single, uninterrupted 90 seconds laser treatment. When performing laser prostatectomy in a noncontact fashion, some superficial charring or carbonization often occurs. This charring can block deeper tissue penetration by the laser energy, rendering the treatment less effective.34%49 Therefore for maximal deep coagulation necrosis to occur, the highest power setting that does not cause carbonization should be used.39x49 Muschter et ~1.~~ have tested a wide variety of laser delivery systems and suggest that 40 W of power with the fiber or reflector tip maintained 1 mm from the tissue is most effective. This finding is consistent with studies performed in the canine mode1.48 In addition to carbonization, another tissue change seen with laser treatment of the prostate is the so-called popcorn effect.34,50 This refers to an eruption of the mucosa during the procedure that occurs due to vaporization of deeper tissues leading to steam formation. This pocket of steam expands, causing rupture of the intact overlying urothelium. The popcorn effect does not cause tissue damage and, although it does lead to decreased superficial heating of the tissue, it does not appear to affect significantly the depth of heating.49 Therefore it has a negligible effect on the overall treatment. SUMMARY Laser treatment of men with BPH remains in its infancy. To date, a large number of techniques and devices have been developed and investigated to varying degrees. Each laser system that is utilized in a unique fashion must be evaluated individually since tissue effects may vary significantly with minor changes in technique or technology Overall, it appears that the majority of men treated by laser prostatectomy experience objective and subjective improvement with short-term follow-up. In
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most cases, further direct comparisons with TURP with longer follow-up are needed to assess adequately the relative efficacy and morbidity of laser therapy Although early results are promising and technologic advances are likely to improve further the results seen with laser treatment of men with BPH, it may be premature to relegate TURP to the history books. Glenn S. Gerber, M.D. University of Chicago Medical Center 5841 S. Maryland Ave. MC 6038 Chicago, IL 60637 REFERENCES 1. Bruskewitz RC, Larsen EH, Madsen PO, and Dorflinger T: 3-year followup of urinary symptoms after transurethral resection of the prostate. J Urol 136: 613-615, 1986. 2. Sander S, and Beisland HO: Laser in the treatment of localized prostatic carcinoma. J Ural 132: 280-281, 1984. 3. Shanberg AM, Tansey LA, and Baghdassarian R: The use of Nd:YAG in prostatectomy. Poster 331, American Urological Association meeting, 1985. 4. Stein BS: Laser-tissue interaction, in Smith JA Jr, Stein BS, and Benson RC Jr: Lasers in Urologic Surgery, 3d ed., St. Louis, Mosby-Year Book, 1994, pp 10-25. 5. McCullough DL, Roth RA, Babayan RK, Gordon JO, Reese JH, Crawford ED, Fuseher HA, Smith JA, Murchison RJ, and Kaye KW: Transurethral ultrasound-guided laserinduced prostatectomy: National Human Cooperative Study results. J Ural (5 pt 2) 150: 1607-1611, 1993. 6. Smith JA Jr: Benign prostatic hypertrophy, in Smith JA Jr, Stein BS, and Benson RC Jr: Lasers in Urologic Surgery, 3d ed., St. Louis, Mosby-Year Book, 1994, pp 83-101. 7. Roth RA, and Aretz HT: Transurethral ultrasoundguided laser-induced prostatectomy (TULIP procedure): a canine prostate feasibility study. J Urol 146: 1128-1135, 1991. 8. Spitzenpfeil E, Thomas ST, Knipper A, and Jocham D: Transurethral ultrasound guided laser prostatectomy: Lubeck experience of 6 months. J Endourol (SuppI) 7: S166, 1993. 9. Puppo P, Perachino M, Ricciotti G, and Scannapieco G: Transurethral laser induced prostatectomy (TULIP): evaluation of symptomatic and urodynamic effectiveness. J Endourol (Suppl) 7: S128, 1993. 10. Roth RA and The TULIP Cooperative Study Group: TULIP-National Human Cooperative Study results. J Endour01 (Suppl) 7: S92, 1993. 11. Roth RA, Babayan R, and Aretz T: TULIPtransurethral ultrasound-guided laser-induced prostatectomy. J Urol 145: 390A, 1991. 12. Schulze H, Martin W, Hoch P, and Senge T: TULIP vs. TURP: a prospective, randomized study. J Ural 151: 228A, 1994. 13. Babayan RK, Roth RA, McCullough DL, Gordon JO, Reese JH, Fuseher HA, Crawford ED, Smith JA, Murchison RJ, and Kaye KW: TULIP-two year results. J UroI 151: 228A, 1994. 14. Schulze H, Martin W, Engelmann U, and Senge T: TULIP-transurethral ultrasound-controlled laser-induced prostatectomy: an alternative to TURP? Urologe A 32: 225-231, 1993.
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15. Flam T, Spitzenpfeil E, Gout A, Peyret C, Chiche R, Thiounn N, Steg A, Zerbib M, and Debre B: TULIP: transurethral ultrasound guided laser-induced prostatectomy. Clinical results after one year. J Urol (Paris) 99: 61-66, 1993. 16. Kabalin JN: Laser prostatectomy performed with a right angle firing neodymium:YAG laser fiber at 40 watts power setting. J Urol 150: 95-99, 1993. 17. Norris JP, Norris DM, Lee RD, and Rubenstein MA: Visual laser ablation of the prostate: clinical experience in 108 patients. J Urol (5 pt 2) 150: 1612-1614, 1993. 18. Shanberg AM, Lee IS, Tansey LA, and Sawyer DE: Extensive neodymium-YAG photoirradiation of the prostate in men with obstructive prostatism. Urology 43: 467471, 1994. 19. Costello AJ, Bowsher WG, Bolton DM, Braslis KG, and Burt J: Laser ablation of the prostate in patients with benign prostatic hypertrophy. Br J Urol 69: 603-608, 1992. 20. Anson KM, Watson GM, Shah TK, and Barnes DG: Laser prostatectomy: our initial experience of a technique in evolution. J Endourol 7: 333-336, 1993. 21. Gill HS, Kabalin JN, Leach GE, Bowers G, and Barken I: Laser ablation of the prostate with the Prolase II lateral firing fiber: a multicenter study. J Endourol (Suppl) 7: S127, 1993. 22. Kreutzer ER, Parker M, and Stein M: Laser ablation of the prostate with the Urolase fiber: early results. J Endourol (Suppl) 7: S165, 1993. 23. Krautschick A, Weber HM, Nonnenmacher AK, Gottfried HW, Hautmann RE, and Frohneberg DH: Transurethral endoscopical laserblation of the prostate (TULAP). J Endourol (Suppl) 7: S167, 1993. 24. Buckley JF, Ligam V, and Paterson P: Endoscopic laser ablation of the prostate gland (ELAP). J Urol 151: 229A, 1994. 25. Dixon C, Machi G, Theune C, Olejniczak G, and Lepor H: A prospective double-blind, randomized study comparing the safety, efficacy and cost of laser ablation of the prostate and transurethral prostatectomy for the treatment of BPH. J Urol 151: 229A, 1994. 26. Kabalin JN: Effect of prostate size on outcome of laser prostatectomy at 6 months. J Urol 151: 230A, 1994. 27. Leach GE, Dmochowski R, Ganabathi K, Broderick GS, Wein AJ, Cowles R, Kabalin JN, and Gill HS: Visual laser assisted prostatectomy (VLAP) using Urolase right angle fiber: multicenter 60 watt protocol. J Urol 151: 228A, 1994. 28. Leach GE, Sirls L, Ganabathi K, Roskamp D, and Dmochowski R: Outpatient visual laser-assisted prostatectomy under local anesthesia. Urology 43: 149-153, 1994. 29. Costello AJ, Johnson DE, and Bolton DM: Nd:YAG laser ablation of the prostate as a treatment for benign prostatic hypertrophy. Lasers Surg Med 12: 121-124, 1992. 30. Marks LS: Serial endoscopy following visual laser ablation of prostate (VLAP). Urology 42: 66-71, 1993. 31. Costello AJ, and Crowe HR: A single institution experience of reflecting laser fiber prostatectomy over four years. J Urol 151: 229A, 1994. 32. Kabalin JN, and Gill HS: Urolase laser prostatectomy in patients on warfarin anticoagulation: a safe treatment alternative for bladder outlet obstruction. Urology 42: 738-740, 1993. 33. Bolton DM, and Costello AJ: Management of benign prostatic hyperplasia by transurethral laser ablation in patients treated with warfarin anticoagulation. J Urol 151: 79-81, 1994.
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34. Kabalin JN: Transurethral laser prostatectomy. Infect Urol May/June: 71-84, 1994. 35. Perkash I, Terris M, Iwakiri J, Cowan B, and Wolfe V: Laser sphincterotomy and ablation of the prostate using a sapphire chisel contact tip firing Nd:YAG laser. J Urol 151: 333A, 1994. 36. Bartsch G, Janetschek G, Watson G, and Anson K: The development of an endoscope and of contact probes for transurethral laser surgery of the prostate. J Urol 151: 333A, 1994. 37. Watson G, Anson K, Janetschek G, Horninger W, and Bartsch G: An indepth evaluation of contact laser vaporisation of the prostate. J Urol 151: 231A, 1994. 38. Muschter R, Zellner M, Hessel S, and Hofstetter A: lnterstitial laser coagulation for benign prostatic hyperplasia. J Endourol (Suppl) 7: S126, 1993. 39. Muschter R, Zellner M, Hessel S, and Hofstetter A: Lasers and benign prostatic hyperplasia-experimental and clinical results to compare different application systems. J Urol 151: 230A, 1994. 40. Orovan WL, and Whelan JP: Neodymium YAG laser treatment of BPH using interstitial thermotherapy; a transurethral approach. J Urol 151: 230A, 1994. 41. Hoopes PJ, Williams JC, Harris RD, Ryan TP, Heaney JA, Andrus WS, Rykhus RL, McNicholas TA, and Wishnow Kl: Interstitial laser coagulation (ILC) of the canine prostate with transrectal ultrasound (TRUS) and thermal monitoring. J Urol 151: 334A, 1994. 42. McNicholas TA, Steger AC, and Bown SG: Interstitial laser coagulation of the prostate. An experimental study. Br J Urol 71: 439444, 1993. 43. Muschter R, Hessel S, Hofstetter A, Keiditsch E, Rothenberger KH, Schneede P, and Frank F: [Interstitial laser coagulation of benign prostatic hyperplasia.] [German.] Urologe A 32: 273-281, 1993. 44. Littrup PJ, Lee F, Borlaza GS, Sacknoff EJ, TorpPedersen S, and Gray JM: Percutaneous ablation of canine prostate using transrectal ultrasound guidance. Absolute ethanol and Nd:YAG laser. Invest Radio1 23: 734-739, 1988. 45. Orihuela E, Motamedi M, Cammack T, and Warren M: Nd:YAG laser barbecue effect in the prostate: application to laser treatment of benign prostatic hyperplasia. J Endourol (Suppl) 7: S62, 1993. 46. Kabalin JN, and Gill HS: Dosimetry studies utilizing the Urolase right angle laser fiber in a canine prostate model. J Endourol (Suppl) 7: S63, 1993. 47. Orihuela E, Pow-sang M, Motamedi M, LaHaye M, Cowan D, and Warren M: Histopathological correlation and randomized clinical trial comparing low power versus high power laser regimens in the human prostate. J Urol 151: 332A, 1994. 48. Kabalin JN, and Gill HS: Dosimetry studies utilizing the Urolase right angle firing neodymium:YAG laser fiber. Lacers Surg Med 14: 145-154, 1994. 49. Perlmutter AP, Lopez MA, and Vaughan ED Jr: The dosimetry of Nd:YAG laser coagulation in the canine prostate: concepts for clinical treatment. J Urol 151: 331A, 1994. 50. Johnson DE, Levinson AK, Greskovich FJ, Cromeens DM, Ro JY, Costello AJ, and Wishnow Kl: Transurethral laser prostatectomy using a right-angle laser-delivery system. SPIE 14~1: 3641, 1991.
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Transurethral resection of the prostate (TURP) has been the gold standard in the treatment of benign prostatic hyperplasia (BPH) for many years. Recently, a number of alternative treatments have been investigated and have gained acceptance to varying degrees. These include the use of oral medications, such as 5-alpha-reductase inhibitors and alpha,-adrenergic antagonists, as well as minimally invasive surgical approaches, such as hyperthermia and the use of laser energy to ablate the prostate. Although the efficacy of TURP in relieving bladder outlet obstruction secondary to prostatic enlargement has been clearly demonstrated,’ the primary reason for the growing popularity of alternative therapeutic approaches to BPH is the potential reduction in morbidity and cost associated with these techniques. The use of laser energy to treat diseases of the prostate was first reported in 1984 by Sander and Beisland.’ These authors treated 16 men with clinically localized prostate cancer with laser energy delivered transurethrally. Short-term results indicated no serious complications and good disease control. In 1985, Shanberg et a1.3 used laser energy to perform transurethral incisions of the prostate (TUIP) in men with symptomatic BPH. Although the use of laser energy adds little to the overall effectiveness of TUIP compared with standard incisional techniques, this was the first step in the rapid proliferation of reports concerning lasers and the treatment of BPH. The technique of laser prostatectomy continues to evolve. This article will review the principles of laser energy as applied to the treatment of BPH, as well as currently available technology Finally, the published results of laser prostatectomy will be reviewed in an attempt to place this procedure in its proper perspective. Submitted: June 9, 1994, accepted (with revisions): September 12,1994
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BACKGROUND The term “laser prostatectomy” encompasses a wide variety of procedures performed using a broad range of techniques and technology. The results achieved with one type of laser energy delivered in a particular fashion may have no bearing on the tissue effects that may be seen using other lasers and modes of delivery. Therefore, the careful reader of literature concerning laser treatment of BPH must pay close attention to technical details regarding each individual procedure. Essentially, the effects of laser energy on prostate tissue are based on thermal action.4 With acute heating up to 6O”C, there is no significant change in the appearance or long-term effect on the tissue. Between 60°C and lOO”C, coagulation necrosis occurs as a result of protein denaturation. The tissue blanches and turns white with resultant slough over several days to weeks. Finally, vaporization of prostate tissue occurs with heating to greater than 100°C. This latter form of treatment leads to immediate ablation of prostate tissue in contrast to the delayed slough seen with coagulative necrosis. The neodymium: yttrium-aluminum - garnet (Nd:YAG) laser has been the most commonly used laser in the treatment of BPH. The Nd:YAG laser emits a wavelength of 1064 nm, which is poorly absorbed by water and hemoglobin, facilitating its endoscopic use in a fluid medium. In addition, the energy is readily transmitted by fiber, and tissue penetration up to 4 to 5 mm may be achieved. However, the limits of penetration of laser energy are not necessarily equivalent to the depth of penetration of significant laser effect.4 This is due to a variety of factors, including lateral diffusion and backscatter of laser energy The magnitude of these effects is based on individual tissue characteristics, but the end result is a proportionate decrease in temperature rise and tissue effect with increasing tissue penetration.4
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The use of lasers in the treatment of BPH may be broadly divided into two categories based on the form of energy delivery: contact and noncontact. In the former case, the primary effect on the prostate is tissue vaporization whereas noncontact laser treatment primarily relies on coagulation necrosis. The main advantage of contact laser treatment of the prostate is immediate relief of obstruction. However, vaporization may be slow and direct contact may lead to rapid damage to the fiber tips, necessitating the use of multiple fibers. The treatment of large prostates may be particularly difficult and time consuming with contact techniques. Initially noncontact laser coagulation was generally unsuccessful in relieving prostate obstruction mainly owing to the use of end fire probes. With this technique, it was very difficult to orient the fiber in proper relationship to the tissue in order to maximize the laser effects. The introduction of right angle delivery systems (side fire) largely overcame this shortcoming and noncontact laser treatment of the prostate has increased rapidly in popularity The advantages of this technique include the speed and ease with which the procedure may be performed, as well as the minimal bleeding that occurs. The primary disadvantage of noncontact treatment is the resultant delayed tissue slough that generally necessitates the use of an indwelling urethral catheter or suprapubic tube for several days to weeks. TRANSURETHRAL ULTRASOUND-GUIDED LASER-INDUCED PROSTATECTOMY The transurethral ultrasound-guided laserinduced prostatectomy (TULIP) system consists of a 20 F probe that is placed transurethrally into the prostatic urethra. Incorporated within this probe is a right angle laser window and an ultrasound transducer. The laser window, through which the laser light is delivered to the tissue, is located between the two halves of the split transducer, which produces a sector scan of the adjacent prostate anatomy The laser energy is delivered into the tissue at a right angle accompanied by simultaneous real-time ultrasound imaging. The entire probe is contained within a 36 F or 48 F balloon (sleeve) filled with sterile water. This balloon allows for optimal ultrasound imaging and also compresses the prostate lobes to allow for consistent spacing between the laser and its target tissue. This spacing prevents charring of the laser fiber and improves penetration by the laser energy.5,6 The balloon is filled to 2 atmospheres of pressure and early work with the TULIP system in the canine model showed no significant prostatic urethral dilation associated
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with this technique, suggesting that beneficial results were related solely to the laser effects.’ The TULIP procedure is generally performed using either regional or general anesthesia.5 Cystoscopy is performed initially followed by positioning of the TULIP probe. The balloon is inflated to 2 atmospheres and the entire prostate is imaged sonographically. The TULIP system is then connected to the Nd:YAG laser, which is set at 30 to 40 W. The prostate is treated by drawing the probe from the bladder neck to a position just proximal to the prostatic apex. This is done at a pull rate of 1 mm/s using continuous sonographic visualization of the prostate. Approximately 8 to 10 passes at varying positions within the prostatic urethra are made based on the sonographic appearance. Cystoscopy is performed after completion of the TULIP procedure to confirm that appropriate laser treatment has occurred. This is demonstrated by the appearance of multiple blanched lines at the treated sites. In most cases, a suprapubic catheter is placed for postoperative bladder drainage. Results of the TULIP procedure have been reported by a number of investigators.5,7-15 The largest study has been conducted by the National Human Cooperative Study group in the United States.5,10,11,13 In the first 150 men treated at 10 different institutions, the mean Boyarsky symptom score decreased from a preoperative level of 18.8 to 6.1 and the mean peak urinary flow rate increased from 6.7 mL/s to a post-treatment rate of 11.9 mL/s at 6 months follow-up.5 These improvements in symptom score and flow rate were similar in a subgroup of 40 men with follow-up of 12 and 24 months.13 The mean estimated blood loss was 17 cc in the 150 treated patients, with no patient requiring a blood transfusion. The average hospital stay was 1.7 days. Short-term complications included lower urinary tract irritative symptoms, which often resolved by 2 to 3 weeks after the procedure, and the need for prolonged bladder drainage. Suprapubic catheters remained in place for an average of 2 weeks, although 20% of the patients required replacement of the catheter due to an inability to void, adequately following suprapubit tube removal. Other authors have found that patients undergoing the TULIP procedure require bladder drainage for much longer periods of time, particulary those with urinary retention preoperatively l2 Using a postvoid residual (PVR) urine value of less than 100 cc as the criteria for suprapubic tube removal, Schulze et aI.” reported that patients required bladder drainage for a mean of 34 days. Long-term complications noted with the TULIP procedure include impotence (4%), urethral
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TABLE I. System
Manufacturer
Lateralase* Urolase ADD’Stat UltraLine Sidefire Prolase II
Trimedyne Bard Laserscope Lasersonics Myriadlase Cytocare
Right angle laser fiber delivery systems * Incident
Delivery
Angle
Arc of Divergence
Fiber Diameter
Reflective Reflective Refractive Refractive Reflective Refractive
90” 90” 70” 80” 105” 45”
30” 30” 20” 20” 15” 35”
600pm 600km 600pm 600k.m 600pm 2mm
Energy
Reflector Diameter 7.5 F 7.5 F NIA N/A 6.3 F N/A
List+ Price ($1 N/A 840 695 595 650 700
*Fiberslistedare thosewith reportedresults ‘EffectiveMay,1994. ‘Notpresentlycommerciallyavailable.
stricture or bladder neck contracture (5%), incontinence (3.8%) and retrograde ejaculation (5.4%).13 Similar results have been reported by other groups.8~9~12~14J5 Schulre et al. performed a randomized study comparing TULIP with TURP in 40 patients. Improvements in peak urinary flow rate, residual urine, and symptom score were similar in the two groups at 6 months follow-up, with slightly better results in all three categories in those treated by TURF! In general, patients treated by the TULIP procedure required a significantly longer period of time to attain improved voiding. This lack of short-term improvement is consistent with the mechanism of tissue slough over several weeks that occurs with the TULIP technique. Overall, the TULIP procedure has been well studied in large groups of patients.* Early results indicate that improvements in symptom score closely approximate those seen with TURP while increases in flow rate are significant but inferior to those achieved with standard prostatic electroresection. The primary advantage of the TULIP procedure is the absence of significant bleeding that allows patients to be treated on an outpatient basis in many cases. However, prolonged catheterization of several days to weeks is usually needed and patients do not have improvement in their symptoms for 1 or 2 months after the procedure. In addition, significant irritative symptoms secondary to local edema and tissue response may persist for many weeks. Nevertheless, by 3 months following the TULIP procedure, the majority of patients will have significant improvement in their symptoms, flow rate, or both, and these results appear to be durable at 1 to 2 years.6 NONCONTACT VISUAL LASER PROSTATECTOMY A variety of right angle delivery systems that are used under direct cystoscopic vision have been
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investigated. This procedure has been called “visual laser ablation of the prostate” (VLAP). Although there are differences among the increasing number of available laser fibers (Table I), the basic principles of energy delivery to prostate tissue are similar. The Nd:YAG laser energy is passed along a 600 to 1000 km fiber and is then reflected or refracted at a 45” to 105” angle into the tissue. The energy delivery occurs over a 15’ to 35” arc of divergence as the fiber tip is maintained approximately 1 mm from the prostate. Reflective systems utilize a 6 to 7.5 F gold or gold-plated alloy dish reflector tip that is glued to the end of the fiber. Tissue effects are largely based on the power setting (40 to 80 W in most cases>, duration of treatment, and the distance maintained between the dish reflector or fiber tip and the prostate (1 mm). In addition, the number of treatment sites also greatly affects the overall result. In most cases, a four quadrant series of laser treatments (2, 4, 8, and 10 o’clock positions) are used in men with prostatic urethral lengths of 2.5 to 4 cm or less. In those patients with a longer prostatic urethra, two series of four quadrant laser burns spaced at equal intervals from the bladder neck to the verumontanum are most frequently used. Alternatively, total tissue ablation with treatment of all visible adenoma of the prostate may be utilized. This type of treatment generally leads to the delivery of much larger amounts of energy, and it has been suggested that total ablation techniques may allow for improved long-term results.ls Further study will be necessary to determine the most appropriate VLAP technique. The potential variability in VLAP treatment techniques may lead to significant differences in laser effects and treatment results among surgeons. This is in contradistinction to the TULIP system in which ,use of a water-filled balloon surrounding the laser fiber allows for constant spacing and more uniform tissue effects and results.
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TABLE II.
Results of noncontact right angle endoscopic controlled Nd:YAG laser prostatectomy
Reference Kabalin16 Norris et al. I7 Shanberg et al. I8 Costello et a/. I9 Anson et a/.*O Gill et a/.*’ Kreutzer et a/.** Krautschick et a/.23 Buckley et a/.24 Dixon et a/.25 Kabalin26 Leach et a/.*’ Leach et al.28
Peak Flow (cc/s) Pre* Post *
Laser System
No. Patients
Urolase Urolase ADD, Urolase Prolase Lateralase Lateralase Sidefire Prolase II Urolase UltraLine Urolase Urolase Urolase Urolase Urolase
13 108 25+ 25$ 17
8.5 7.6 5.7 6.5 5
12 50 22 39 77 20 62 50 28
11 10.5 8.8 7.3 9.9 9.2 7.7 7.4 8.1
Symptom
Score
Length of Follow-up (mo.)
Pre
Post
20.5 12 13.5 14.5 9
20.9 22.3 26.5 25.6 15
4.6 12.6 7.8 5.2 4
6 3-6 4-16 4-16 l-l.5
13 16.6 10.7 19.3 17.5 14.1 15.8 16 13.0
23 18.9 NIA 32 19 16.5 20.9 21 21
9 9.7 NIA 5 6 11.9 9.9 8.3 9.4
3 3 6 3 6 6 6 12 6
*pre = pretreatment; Post = post-treatment. ‘Patients treated by 4 OT8 quadrant technique. ‘Patients treated by total tissue ablation technique.
A large number of investigators have reported results using the VLAP technique (Table II).16-31 In general, these studies indicate significant improvements in peak flow rate and symptom score with 3 to 12 months of follow-up. Randomized studies comparing VLAP and TURP have also been reported.16~24~25~30Th ese also indicate significant objective and subjective improvements with the laser technique, although the results are not as good as those achieved with TURP in some cases. Buckley et a1.24 noted that 1 year following TURP or VLAP using the Urolase fiber improvements in symptom score and PVR were similar but flow rate was better in the TURP group. Dixon et ~1.~~ also compared these procedures and found that symptom score reduction was superior with TURP at 12 months follow-up. In addition, improvements in PVR and flow rate were also better with TURP but were not statistically significant. Most importantly, 41% of men treated by VLAP were dissatisfied with the results of the procedure or had required repeat surgery by 1 year compared with 11% in the TURP group. In contrast, Kabalin16 noted equivalent efficacy at 6 months in 25 men randomized to TURP and VLAP as assessed by symptom score, flow rate, and PVR. The complications of VLAP include lower urinary tract irritative symptoms that may not resolve for 1 to 2 months. In addition, postoperative bladder drainage is usually necessary for several days, with a small percentage of patients requiring a catheter for up to several weeks. Increased duration of catheterization is strongly associated with
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pretreatment urinary retention.17 Finally, changes in sexual function have also been noted following VLAI? Leach et a1.27 reported a loss of potency in 5 of 117 (4.3%) men treated with the Urolase fiber2’ and the incidence of retrograde ejaculation is approximately 5% to 1O%.‘6,27 One of the most important advantages of the VLAP procedure is the lack of significant bleeding associated with the technique. Transfusions have been unnecessary in large groups of treated patients and in most cases the procedure can be performed on an outpatient basis without the need for catheter irrigation.17 In addition, patients can be safely treated while fully anticoagulated.32,33 In comparison with the TULIP technique, the VLAP procedure appears to be subject to greater variability in results. This is largely due to the use of a large variety of right angle delivery systems as well as significant differences in surgical technique used by individual treating physicians. As emphasized earlier, results achieved with VLAP may not be reproducible using alternative laser fibers and treatment strategies. CONTACT LASER VAPORIZATION OF THE PROSTATE Although a large number of researchers have investigated and published results using a variety of noncontact right angle delivery systems, information regarding the use of contact laser treatment of men with BPH is limited. Contact vaporization is performed most commonly using the Nd:YAG laser and conventional fibers. A contact tip of
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fused silica quartz or synthetic sapphire is connected to the fiber, and treatment is performed by placing this tip directly against the prostate. The laser energy is rapidly converted to thermal energy as it enters the tip, which produces intense heat and immediate removal of tissue.34 Initial attempts at direct vaporization of prostate tissue were largely unsuccessful due to the slow and tedious nature of the procedure as well as rapid fiber tip destruction. 6 Recently, several investigators have used larger (3 to 5 mm), more durable fiber tips that increase energy delivery and may make it possible to vaporize obstructing adenomatous tissue more efficiently.35-37 There is significant theoretic advantage to contact vaporization of the prostate compared with noncontact coagulation necrosis. At the completion of a successful treatment using contact techniques, a large open cavity is created in the prostatic fossa leading to immediate relief of obstruction. This allows for early catheter removal and rapid improvement in obstructive symptoms. In addition, it appears that the lower urinary tract irritative symptoms that often occur after right angle coagulation of the prostate are much less common with contact vaporization. 36 The primary disadvantages of direct contact treatment are the inability to ablate large prostates effectively and less effective hemostasis compared with noncontact procedures. Published results of contact laser vaporization of the prostate are limited. Watson et ~1.~~performed an initial pilot study in 60 men using the Nd:YAG laser and fused silica tips of up to 3.5 to 5.0 mm in diameter. Limited results indicated significant improvements in flow rate and symptom score with short-term follow-up. Other authors have reported minimal bleeding with contact treatment in small groups of patients and believe that prostates up to 50 cc in volume may be successfully treated. 35-37The continued development and refinement of contact probes and delivery systems are likely to improve the efficacy of contact vaporization of the prostate. If these technical advances lead to efficient and effective removal of large amounts of prostate tissue, the benefits of immediate symptom improvement and early catheter removal may allow contact vaporization to supersede noncontact right angle techniques as the preferred method of laser prostatectomy. INTERSTITIAL LASER TREATMENT OF THE PROSTATE An alternative method of laser prostatectomy that has been investigated involves the interstitial placement of laser fibers directly into the prostate UROLOGY@ / FEBRUARY 1995 I VOLUME45, NUMBER2
parenchyma.38-44 The fibers are fitted with special diffuser tips and are most commonly inserted through needle guides that are placed percutaneously through the perineum or directly into the prostate via a cystoscope. Fiber placement and subsequent treatment using the Nd:YAG laser are continuously monitored using transrectal ultrasonography. Interstitial laser treatment of the prostate allows for preservation of the urothelium, thus preventing tissue slough leading to potentially less irritative symptoms than are seen with other laser techniques. Interstitial laser therapy in canine prostates leads to the formation of extensive zones of coagulation necrosis surrounding the site of laser treatment.41,43,44The size of these zones correlates well with the power delivered and over the course of 7 weeks following the treatment, scars are formed with cellular degeneration and necrosis and associated tissue shrinkage. 43 A small number of studies using interstitial laser treatment in men with BPH have been reported.38-40,43 Muschter et a1.38 treated 184 patients over a 2-year period. Six months follow-up was available in 134 (73%) of these men, with significant improvements in the mean symptom score, flow rate, and postvoid residual urine noted. Ten patients underwent TURP due to persistent obstruction. Other studies have also demonstrated objective and subjective improvement in smaller groups of patients with 2 to 6 months of follow-up.39,40,43In general, bleeding was absent or minimal, short periods of catheterization were needed, and sexual function, including antegrade ejaculation, was preserved. Interstitial laser treatment of the prostate is a promising technique that will require more rigorous testing with longer follow-up before its true value and efficacy can be determined. DOSIMETRY AND TECHNICAL CONSIDERATIONS Presently, the greatest experience with lasers in the treatment of BPH has been with right angle noncontact techniques performed under direct vision (VLAP) or with ultrasound guidance (TULIP). Although good results have been reported using a variety of laser systems and techniques, there is limited information available concerning the most effective power setting, duration of energy delivery, and the resultant effects on prostate tissue. Most of the early work with the Urolase system consisted of treatment of the lateral lobes with 60 W of power for 60 seconds followed by the same or lesser energy delivery to the roof and floor of the prostatic fossa. 16,17,28 However, studies in 197
canine and human prostates have suggested that peak tissue effects are achieved with lower power settings (15 to 40 W) used for longer intervals (90 seconds). 45-48Kabalin and Gi1148 used the Urolase fiber in 29 canine prostates at variable power settings and treatment durations. Peak tissue ablation occured at 40 W with up to 21 mm tissue penetration and a mean depth of tissue destruction that was more than 30% greater than that seen with a power setting of 60 W. Similarly, the mean volume of tissue ablation was more than 60% greater at 40 W than at 60 W. In addition, using a constant power setting of 40 W, tissue effects were noted to rise steadily and then plateau beyond 90 seconds. Finally, discontinuous energy delivery significantly decreased the observed tissue effects compared with a single, uninterrupted 90 seconds laser treatment. When performing laser prostatectomy in a noncontact fashion, some superficial charring or carbonization often occurs. This charring can block deeper tissue penetration by the laser energy, rendering the treatment less effective.34%49 Therefore for maximal deep coagulation necrosis to occur, the highest power setting that does not cause carbonization should be used.39x49 Muschter et ~1.~~ have tested a wide variety of laser delivery systems and suggest that 40 W of power with the fiber or reflector tip maintained 1 mm from the tissue is most effective. This finding is consistent with studies performed in the canine mode1.48 In addition to carbonization, another tissue change seen with laser treatment of the prostate is the so-called popcorn effect.34,50 This refers to an eruption of the mucosa during the procedure that occurs due to vaporization of deeper tissues leading to steam formation. This pocket of steam expands, causing rupture of the intact overlying urothelium. The popcorn effect does not cause tissue damage and, although it does lead to decreased superficial heating of the tissue, it does not appear to affect significantly the depth of heating.49 Therefore it has a negligible effect on the overall treatment. SUMMARY Laser treatment of men with BPH remains in its infancy. To date, a large number of techniques and devices have been developed and investigated to varying degrees. Each laser system that is utilized in a unique fashion must be evaluated individually since tissue effects may vary significantly with minor changes in technique or technology Overall, it appears that the majority of men treated by laser prostatectomy experience objective and subjective improvement with short-term follow-up. In
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most cases, further direct comparisons with TURP with longer follow-up are needed to assess adequately the relative efficacy and morbidity of laser therapy Although early results are promising and technologic advances are likely to improve further the results seen with laser treatment of men with BPH, it may be premature to relegate TURP to the history books. Glenn S. Gerber, M.D. University of Chicago Medical Center 5841 S. Maryland Ave. MC 6038 Chicago, IL 60637 REFERENCES 1. Bruskewitz RC, Larsen EH, Madsen PO, and Dorflinger T: 3-year followup of urinary symptoms after transurethral resection of the prostate. J Urol 136: 613-615, 1986. 2. Sander S, and Beisland HO: Laser in the treatment of localized prostatic carcinoma. J Ural 132: 280-281, 1984. 3. Shanberg AM, Tansey LA, and Baghdassarian R: The use of Nd:YAG in prostatectomy. Poster 331, American Urological Association meeting, 1985. 4. Stein BS: Laser-tissue interaction, in Smith JA Jr, Stein BS, and Benson RC Jr: Lasers in Urologic Surgery, 3d ed., St. Louis, Mosby-Year Book, 1994, pp 10-25. 5. McCullough DL, Roth RA, Babayan RK, Gordon JO, Reese JH, Crawford ED, Fuseher HA, Smith JA, Murchison RJ, and Kaye KW: Transurethral ultrasound-guided laserinduced prostatectomy: National Human Cooperative Study results. J Ural (5 pt 2) 150: 1607-1611, 1993. 6. Smith JA Jr: Benign prostatic hypertrophy, in Smith JA Jr, Stein BS, and Benson RC Jr: Lasers in Urologic Surgery, 3d ed., St. Louis, Mosby-Year Book, 1994, pp 83-101. 7. Roth RA, and Aretz HT: Transurethral ultrasoundguided laser-induced prostatectomy (TULIP procedure): a canine prostate feasibility study. J Urol 146: 1128-1135, 1991. 8. Spitzenpfeil E, Thomas ST, Knipper A, and Jocham D: Transurethral ultrasound guided laser prostatectomy: Lubeck experience of 6 months. J Endourol (SuppI) 7: S166, 1993. 9. Puppo P, Perachino M, Ricciotti G, and Scannapieco G: Transurethral laser induced prostatectomy (TULIP): evaluation of symptomatic and urodynamic effectiveness. J Endourol (Suppl) 7: S128, 1993. 10. Roth RA and The TULIP Cooperative Study Group: TULIP-National Human Cooperative Study results. J Endour01 (Suppl) 7: S92, 1993. 11. Roth RA, Babayan R, and Aretz T: TULIPtransurethral ultrasound-guided laser-induced prostatectomy. J Urol 145: 390A, 1991. 12. Schulze H, Martin W, Hoch P, and Senge T: TULIP vs. TURP: a prospective, randomized study. J Ural 151: 228A, 1994. 13. Babayan RK, Roth RA, McCullough DL, Gordon JO, Reese JH, Fuseher HA, Crawford ED, Smith JA, Murchison RJ, and Kaye KW: TULIP-two year results. J UroI 151: 228A, 1994. 14. Schulze H, Martin W, Engelmann U, and Senge T: TULIP-transurethral ultrasound-controlled laser-induced prostatectomy: an alternative to TURP? Urologe A 32: 225-231, 1993.
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