- Email: [email protected]
Current Status of Laser Treatment of BPH
Med. Laser Appl. 16: 5–14 (2001) © Urban & Fischer Verlag http://www.urbanfischer.de/journals/lasermed
Current Status of Laser Treatment of BPH ROLF MUSCHTER Department of Urology, Diakoniekrankenhaus Rotenburg/Wümme, Germany Submitted: December 2000 · Accepted: January 2001
Summary Several minimally-invasive procedures utilizing laser technology have been introduced in the recent past for the treatment of BPH. Laser treatment of BPH summarizes a variety of techniques using different laser wavelengths, application systems and surgical techniques to achieve contrasting tissue effects such as incision, resection, vaporization, or coagulation. Many studies including randomized trials versus TURP have proven the clinical efficacy of laser treatment of BPH, urodynamic controls confirmed effective unobstruction was achieved. Long-term followup of up to 5 years have demonstrated the durability of the results. Complication rates were much lower compared to TURP, retreatment rates were usually higher than after TURP. Another disadvantage of laser coagulation is an initial increase of obstruction due to the heat associated edema and tissue hardening requiring postoperative catheterization for days or weeks, according to the detrusor function. These problem is not shared by laser vaporization and resection techniques, however, these are difficult to learn, and require usually a long operation time.
Key words Benign prostatic hyperplasia, laser treatment, minimally-invasive therapy, laser coagulation, interstitial laser coagulation, laser resection, laser enucleation, laser vaporization
Introduction During the past 10 years, several so-called minimallyinvasive procedures for the treatment of BPH have been introduced, many of them utilizing laser technology. The term “laser treatment of BPH”, however, summarizes a variety of techniques using different laser wavelengths, application systems and surgical techniques to achieve contrasting tissue effects such as incision, resection, vaporization, or coagulation (Tab.1). All these procedures are based on the same principle: the transmission of laser energy into heat. Dependent on the laser wavelength or its penetration depth, respectively, and the power density, which is a function of laser output power, applicator size or beam divergency and distance between applicator and irradiated surface, and application technique, the resulting tissue effect is either coagulation or vaporization.
Table 1. Laser procedures for the treatment of BPH. transurethral incision of the prostate (TUIP) transurethral ultrasound-guided laser-induced prostatectomy (TULIP) visual/endoscopic laser ablation of the prostate (VLAP, ELAP, LAP) interstitial laser coagulation/thermotherapy (ILK, ILC, LITT, ITT) transurethral laser ablation/evaporization of the prostate (TULAP, TUEP) contact laser vaporization (CLV) transurethral ballon laser thermotherapy (TUBAL-T) holmium laser ablation of the prostate (HoLAP) combined endoscopic laser ablation of the prostate (CELAP) holmium laser resection of the prostate (HoLRP) holmium laser enucleation of the prostate (HoLEP) Nd: YAG/vaportrode laser resection of the prostate 1615–1615/01/16/01-005 $ 15.00/0
6
R. MUSCHTER
Coagulation can be achieved by superficial or interstitial laser application. Vaporization can occur using free beam or contact laser irradiation and can be broad, which is called ablation, or narrow, which is called incision, when the applicator is moved. Two or more incisions connected with each other result in a resection of tissue or enucleation, respectively, if the whole adenoma is removed.
Current Laser Techniques Currently, some laser procedures are only of historical interest. Those being relevant in clinical use are:
Transurethral Laser Coagulation Transurethral laser coagulation, with all synonyms such as visual laser ablation of the prostate (VLAP), side-fire laser, etcetera: In this procedure, the prostate
is irradiated by free beam Nd:YAG or diode laser energy, which is transmitted through a flexible fiber with a deflecting tip to achieve more or less perpendicular irradiation (Fig.1). Depending on the type of applicator used, laser energy is delivered to the urethral surface by “fixed position lasing”, usually using the “four-quadrant technique” with constant laser power and radiation time, or with the laser applicator moved along the surface in a certain way, called “pulling” or “painting”. In any case, the goal of treatment is to achieve deep and homogeneous coagulation necrosis. Consecutively, the necrotized tissue sloughs off within weeks after treatment. The problem with this technique, however, is the unpredictable depth of the lesion really achieved due to superficial carbonization (Fig. 2). If this occurs during the initial phase of laser irradiation, all energy administered consecutively is absorbed by the char preventing any light to penetrate deeper. In most recommended laser schemes with only few treatment sites with fixed radiation times, however, there is no control if and when superficial char occurs and, therefore a lot of tissue may be left untreated without being recognized.
Interstitial laser coagulation
Fig. 1. Visual laser ablation of the prostate.
Fig. 2. Potential surgical failures: intent-to-treat versus real-effect in transurethral laser coagulation of the prostate.
In contrast to the free beam laser irradiation approach, the objective of ILC is to achieve coagulation necrosis inside the adenoma, rather than at its urethral surface (Fig. 3). The interstitial coagulation results in secondary atrophy and regression of the prostatic lobes. This is in contrast to the sloughing of necrotic tissue which occurs after free beam coagulation. Both Nd:YAG and diode lasers can be used for ILC because of their relatively deep penetration in water, efficient volumetric tissue heat loading, and the ability to be delivered through flexible optical fibers. The goal of creating the largest coagulative volume in the shortest amount of surgical time is accomplished by initiating irradiation with a relatively high power to rapidly heat the tissue and coagulate the blood vessels, followed by laser power reduction in order to maintain the temperature in the center of the lesion at a high level just below the carbonization threshold, and allow further lesion expansion. Therefore, the optimal irradiation parameters vary for different laser wavelength and applicator
Current Status of Laser Treatment of BPH
7
Fig. 3. Interstitial laser coagulation of the prostate.
Fig. 4. Temperature feedback control for interstitial laser coagulation.
Fig. 6. Potential surgical failures: intent-to-treat versus real-effect in interstitial laser coagulation.
Fig. 5. Interstitial laser coagulation of the apex of the left side lobe.
combinations. On-line temperature monitoring by an integrated thermocouple allows further optimization by use of a power feedback control (Fig. 4), and optical feedback systems can detect carbonization.
This prevents overheating and fiber damage as well as the tissue char which would limit laser penetration. ILC is usually performed using the transurethral cystoscopic approach (Fig. 5), although the percutaneous perineal approach, in which the laser applicator is introduced through hollow needles in the perineum guided by transrectal ultrasound, is also possible. The learning curve of ILC is short, however, ILC is a surgical technique and requires a correct fiber placement to be successfully performed (Fig. 6).
8
R. MUSCHTER
cator, e.g. the contact probe. Therefore, the volume effect is visible in total. The broader the vaporized area, the more tissue is ablated, the narrower the area of vaporization is, the more a cut results.
Transurethral laser resection or enucleation
Fig. 7. Laser vaporization of the prostate.
Transurethral laser vaporisation For this technique, an Nd:YAG or diode laser is used either with a special contact tip connected to the end of the transmission fiber, or a bare fiber or a common side-firing fiber is used at high laser power settings or high power densities, respectively. Alternatively, the KTP laser with a medium deep tissue penetration is also capable for laser vaporization. Regardless of the wavelength used, tissue effects are alike (Fig. 7): In the initial phase of laser irradiation the tissue water is vaporized, consecutively, the remaining desiccated tissue burns and turns into char. Adjacent to the superficial char is a small layer of coagulation predominantly achieved by heat conduction. The char is either burned at high temperatures by continuing irradiation or mechanically removed by the laser appli-
Transurethral laser resection or enucleation, respectively (Fig. 8): This procedure is similar to a standard transurethral electroresection of the prostate, because the prostate tissue is resected. The procedure is usually performed with a holmium:YAG laser and a bare fiber, but was also done using a Nd:YAG laser with a bare fiber as well as a special contact tip. In holmium laser enucleation of the prostate, two incisions are performed in the 5 and 7 o’clock positions from the bladder neck through to the verumontanum down to the capsule. At the level of the veru, the incisions are connected with each other. The middle lobe is then enucleated in toto by dissecting it from the capsule. The resection starts at the veru and commences towards the bladder until the lobe is finally cut off. Next steps are incisions in the 11 and 1 o’clock positions and a curved incision along the external sphincter on each side to connect the dorsal and ventral incisions, open the plane between the side lobes and the capsule at the apex and begin the enucleation of the side lobes. This is finalized the same way as the middle lobe is resected. Besides a long learning curve to perform the procedure, the problem is to remove the big tissue pieces from the bladder.
Fig. 8. Holmium laser enucleation of the prostate.
Current Status of Laser Treatment of BPH
This usually requires a tissue morcellator, which can cause potential complications, is time consuming and costly. However, because the enucleation is performed in one single plane, there is almost no bleeding during the procedure resulting in a far lower complication rate compared to TURP with the same efficacy as TURP because the tissue is removed completely and immediately.
Clinical Results In the past years, many studies have proven the clinical efficacy of the mentioned laser treatments of BPH including randomized studies versus TURP (8,14,29,30,34,35,37). Urodynamic controls confirmed that an effective unobstruction was achieved (18,28). In recent studies, long-term follow-up of up to 5 years have demonstrated the durability of the results, although in some of the studies, retreatment rates were higher than after TURP.
9
rate of only 1.8% in 57 patients after 36 months, while Schatzl from Marberger’s group (27) in a nonrandomized study reported a retreatment rate of 26.7% after 24 months (Tab. 2). The TURP group required a second operation in 4 %. The improvement of symptoms of the not retreated patients, however, sustained at a high level. Qmax improvement was less pronounced (Fig. 9). Pressure-flow data were analyzed in several studies. In a metaanalysis of the literature, Floratos and de la Rosette (9) demonstrated a significant decrease of obstruction after laser coagulation treatment. The published results, however, are in contrast to the decreasing popularity of the technique. Table 2. Long-term retreatment rate of visual laser ablation of the prostate (3, 6, 27). author
n
follow-up
retreatment
Costello and Kabalin Chertin et al. Schatzl et al.
428 57 15
36 mon 36 mon 24 mon
6.8% 1.8% 26.7%
Transurethral laser coagulation Transurethral laser coagulation, predominantly VLAP, has shown excellent results in past and recent publications (6,32). In newer randomized studies some voiding parameters were improved almost to the level of TURP (8,14,30). Costello and Kabalin (5) reported in long-term follow-up of 428 patients for 24 to 36 months a retreatment rate of 6.8 %. In 20 patients IPSS after 36 months had improved to 5.7 from a baseline of 19.9, and the peak flow rate to 19.7 ml/s from a baseline of 7.7 ml/s. Chertin and coworkers (3) had a retreatment
Interstitial laser coagulation Several studies showing good results of ILC were published in the past (1, 25, 26) (Tab. 3). Most of the recent studies were based on the use of diode lasers (5, 7, 13, 20, 24, 33, 36). These confirm the former results, however, there are contrasting findings. Although symptomatic improvement can be seen in all of the studies, voiding parameters can be improved to a high level or less significant (Tab. 4). Looking on the laser system employed and the technique used, it becomes obvious that two different concepts exist,
Fig. 9. Long-term randomized results of visual laser ablation of the prostate [study of Schatzl et al.: Eur Urol 37, 2000 (27)].
10
R. MUSCHTER
Table 3. ILC: Clinical Results 1994–1997 (25). author
n
IPSS preop
IPSS postop
Qmax preop (ml/s)
Qmax postop (ml/s)
Arai et al. 1996 De la Rosette et al. 1997 Henkel et al. 1995 Horninger et al. 1995 Martov and Kilchukov 1996 McNicholas and Alsudani 1996 Muschter and Hofstetter 1994 Muschter et al. 1995 Muschter et al. 1996a Muschter et al. 1996b Orovan and Whelan 1994 Roggan et al. 1994 Schettini et al. 1996 Whelan 1997 Zhenghua and Cilling 1996
70 25 35 12 25 36 239 48 112 42 16 27 20 112 78
18.9 20.6 21 29 19.9 22 25.4 31.0 20.9 22.1 16.3 14 22.6 18.2 22.5
7.7 6.9 8 6 13.5 7 6.1 2.3 7.9 4.2 5.8 5 9.2 8.2 8.5
6.7 9.1 5.3 8.3 8.7 9.4 7.7 9.4 8.0 8.2 8.8 8.0 7.9 10.4 9.8
10.0 20.3 10.0 16.9 13.5 14.6 17.8 19.7 14.2 24.9 11.9 13.0 15.0 17.0 16.5
Table 4. ILC: Clinical Results Diode Laser 1996–2000 (24). author
n
follow-up (mon)
I-PSS baseline
I-PSS post ILC
Qmax baseline (ml/s)
Qmax post ILC (ml/s)
Conn et al. 1996 Conn et al. 1999 Daehlin/Hedlund 1999 Greenberger/Steiner 1998 Lynch 2000 Martov et al. 1998 Muschter et al. 1996 de la Rosette et al. 1997 Schettini et al. 1996 Williams 1998 Williams 2000
12 165 49 25 39 42 112 25 20 25 165
3 12 12 6 6 24 6 3 3 12 18
22.6 22.4 22 20.2 23.5 23.7 20.9 20.6 22.5 23.2 22.1
6.0 8.3 11 8.8 6.1 9.2 7.9 6.9 8.5 7.2 8.8
7.1 8.6 8.6 8.3 8.4 6.5 8 9.1 7.9 8.4 8.6
14.1 14.2 9.9 14.1 18.4 13.9 14.2 20.3 15.0 16.8 14.6
Fig. 10. Low versus high volume coagulation in ILC.
the low and the high volume approach (Fig. 10). In the high volume coagulation technique, not only symptoms and voiding parameters, but also the prostate volume is significantly reduced (25). A direct comparison of two multicenter studies performed simultaneously with a low volume 830–nm laser, one not randomized and one randomized versus TURP to another study performed later in the same centers using an improved high volume laser demonstrates almost no difference in the symptomatic improvement (Fig. 11). However, the peak flow increase, which is lower than TURP in the low-volume approach, reaches the level of TURP in the high-volume technique (24).
Current Status of Laser Treatment of BPH
11
Fig. 11. Low versus high volume coagulation in ILC: clinical results (24).
Fig. 12. Long-term randomized results of contact laser vaporization of the prostate [study of Keoghane et al.: BJU int 86, 2000 (17)].
Long-term results by use of the Nd:YAG laser ILC in 47 high-risk patients, as reported by Krautschick from Alken’s group (18), showed excellent and sustained results 24 months after ILC in all parameters including pressure-flow studies. The detrusor pressure at Qmax decreased from a baseline of 90 cmH2O to 42 cmH2O, while the prostate volume decreased by an average of 14 ml (18).
Transurethral laser vaporization Recently the 5-year follow-up data of a randomized study comparing contact laser vaporization with TURP have been published (16,17). Within 5 years, 18 % of the laser patients and 14.5 % of the TURP patients required retreatment showing no
significant differences between the two groups. IPSS decreased from 19.5 to 9.7 after laser and from 20.2 to 7.0 after TURP. In both groups, the peak flow rate after 5 years was 14.0 ml/s from a baseline of 12.0 ml/s before laser and 9.0 ml/s before TURP (Fig. 12). For the free beam vaporization technique and the KTP laser, 12-months results were reported recently demonstrating comparable results to the early VLAP or contact laser data (2, 19, 22, 30, 31).
Transurethral laser resection and enucleation In contrast to other laser techniques, most studies employing the holmium laser enucleation technique demonstrate clinical improvement equivalent to
12
R. MUSCHTER
Fig. 13. Randomized clinical results of HoLEP [study of Gilling et al.: J Urol 162, 1999 (12)].
TURP in all clinical parameters at a lower complication rate (4, 10, 15, 21, 23). In single studies, HoLEP is even better than TURP. Studies on big prostates over 60 ml were also published (11). Using a tissue morcellator for tissue removal from the bladder, treatment times become acceptable. Postoperative irrigation, catheterization and hospitalisation was shorter for the laser resection groups. To date, however, only 12 months results are available (12) (Fig. 13). Because the tissue is removed , however, at least theoretically no long-term disadvantage should be expected.
Conclusion Laser treatment of BPH has left its infancy and has matured. For good clinical results, however, the user needs to accept the requirements of success which is proper training. It is not only important to know the basics of lasers and laser-tissue interaction. It is mandatory to understand the procedure, and to use the adequate technology and adequate surgical technique. Limitations of the techniques must be taken into account. In all coagulation techniques, not only those using laser technology, an initial increase of obstruction due to the heat associated edema and tissue hardening must be expected. The volume reduction does not occur immediately, but delayed. This requires postoperative catheterization for days or weeks, according to the detrusor function. These problems are not shared by the laser vaporization and resection techniques. However, these are difficult to learn, and require usually a long operation time.
Aktueller Stand der Laserbehandlung der BPH In den letzten Jahren wurden zahlreiche minimal-invasive Verfahren, die Laserenergie für die Behandlung der BPH einsetzen, vorgestellt. Unter dem Begriff Laserbehandlung der BPH werden verschiedene Techniken zusammengefaßt, denen verschiedene Wellenlängen, Applikationssysteme und chirurgische Verfahren zugrundeliegen und die sehr unterschiedliche Gewebeeffekte, wie Inzision, Resektion, Vaporisation und Koagulation erzielen können. Viele Studien, auch prospektiv gegen die TURP randomisierte, haben die klinische Wirksamkeit der Lasertherapie der BPH gezeigt. Mit Hilfe urodynamischer Untersuchungen konnte gezeigt werden, daß eine wirksame Verringerung der Obstruktion erreicht werden kann. Langzeitbeobachtungen über bis zu 5 Jahre konnten die anhaltende Effektivität zeigen. Die Komplikationsraten waren deutlich geringer, die Wiederbehandlungsrate dagegen in der Regel höher, als bei der TURP. Ein weiterer Nachteil der Laserkoagulation ist die initiale Zunahme der Obstruktion aufgrund hitzebedingter Ödeme und Gewebeverhärtungen, die in Abhängigkeit von der Detrusorfunktion eine postoperative Katheterableitung des Harns für Tage oder Wochen bedingt. Dieses Problem besteht bei der Laservaporisation oder –resektion nicht, diese Verfahren erfordern allerdings eine längere Lernkurve und normalerweise relativ lange Operationszeiten.
Schlüsselwörter Benigne Prostatahyperplasie, Lasertherapie, minimal-invasive Therapie, Laserkoagulation, interstitielle Laserkoagulation, Laserresektion, Laserenukleation, Laservaporisation
References 1. ARAI, Y., K. OKUBO, T. OKADA, S. MAEKAWA, Y. AOKI and H. MAEDA: Interstitial laser coagulation for management of benign prostatic hyperplasia: a Japanese experience. J Urol 159, 1998, 1961–1965. 2. CARTER, A., H. SELLS, M. SPEAKMAN, P. EWINGS, P. O’BOYLE, and R. MACDONAGH: Quality of life changes following
Current Status of Laser Treatment of BPH
3.
4.
5.
6. 7.
8.
KTP/Nd:YAG laser treatment of the prostate and TURP. Eur Urol 36, 1999, 92–98. CHERTIN, B., E. Z. MORIEL, I. HADAS-HALPERIN, W. ABUARAFEH, S. LUPA, M. ZILBERMAN, and A. FARKAS: Laser prostatectomy – long-term follow up of 303 patients. Eur Urol 35, 1999, 285–288. CHILTON C. P., I. P. MUNDY, and O. WISEMAN: Results of holmium laser resection of the prostate for benign prostatic hyperplasia. J Endourol 14, 2000, 533–540. COSTELLO A. J., D. K. AGRARWAL, H. R. CROWE and W. J. LYNCH: Evaluation of interstitial diode laser therapy for treatment of benign prostatic hyperplasia. Tech Urol 5, 1999, 202–206. COSTELLO A. J., and J. N. KABALIN: Side-firing neodymium: yag laser prostatectomy. Eur Urol 35, 1999, 138–146. DAEHLIN, L., and H. HEDLUND: Interstitial laser coagulation in patients with lower urinary tract symptoms from benign prostatic obstruction: treatment under sedoanalgesia with pressure-flow evaluation. BJU Int 84, 1999, 628–636. DONOVAN, J. L., T. J. PETERS, D. E. NEAL, S. T. BROOKES, S. GUJRAL, K. N. CHACKO, M. WRIGHT, L. G. KENNEDY, and P. ABRAMS: A randomized trial comparing transurethal resection of the prostate, laser therapy and conservative treatment of men with symptoms associated with benign prostatic enlargement: the CLasP study. J Urol 164, 2000, 65–70.
13
9. FLORATOS, D. L., and J. J. M. C. H. DE LA ROSETTE: The value of urodynamics in laser prostatectomy. Eur Urol 37, 2000, 509–516. 10. GILLING, P. J., C. B. CASS, A. MALCOLM, M. CRESSWELL, M. R. FRAUNDORFER, and J. N. KABALIN: Holmium laser resection of the prostate versus neodymium: yttrium-aluminiumgarnet visual laser ablation of the prostate: a randomized prospective comparison of two techniques for laser prostatectomy. Urology 51, 1998, 573–577. 11. GILLING P. J., K. M. KENNETT, and M. R. FRAUNDORFER: Holmium laser enucleation of the prostate for glands larger than 100 g: an endourologic alternative to open prostatectomy. J Endourol 14, 2000, 529–530. 12. GILLING, P. J., M. MACKEY, M. CRESSWELL, K. KENNETT, J. N. KABALIN, and M. R. FRAUNDORFER: Holmium laser versus transurethral resection of the prostate: a randomized prospective trial with 1-year followup. J Urol 162, 1999, 1640–1644. 13. GREENBERGER, M., and M. S. STEINER: The University of Tennessee experience with the Indigo 830e laser device for the minimally invasive treatment of benign prostatic hyperplasia: interim analysis: World J Urol 16, 1998, 386–391. 14. GUJRAL, S., P. ABRAMS, J. L. DONOVAN, D. E. NEAL, S. T. BROOKES, K. N. CHACKO, M. J. P. WRIGHT, A. G. TIMONEY,
Anzeige
14
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25. 26. 27.
R. MUSCHTER and T. J. PETERS: A prospective randomized trial comparing transurethral resection of the prostate and laser therapy in men with chronic urinary retention: the CLasP study. J Urol 164, 2000, 59–64. KABALIN, J. N., P. J. GILLING, and M. R. FRAUNDORFER: Holmium-yttrium-aluminium-garnet laser prostatectomy. Mayo Clin Proc. 73, 1998, 792–797. KEOGHANE, S. R., K. C. LAWRENCE, A. M. GRAY, H. A. DOLL, A. M. HANCOCK, K. TURNER, M. E. SULLIVAN, O. DYAR, and D. W. CRANSTON: A double-blind randomized controlled trial and economic evaluation of transurethral resection vs contact laser vaporization for benign prostatic enlargement: a 3-year follow-up. BJU Int 85, 2000, 74–80. KEOGHANE, S. R., M. E. SULLIVAN, H. A. DOLL, J. KOURAMBAS, and D. W. CRANSTON: Five-year data from the Oxford laser prostatectomy trial. BJU Int 86, 2000, 227-228. KRAUTSCHICK, A. W., K. U. KÖHRMANN, T. O. HENKEL, M. S. MICHEL, and P. ALKEN: Interstitial laser coagulation in benign prostatic hyperplasia. A critical evaluation after 2 years of follow-up. Urol Int 62, 1999, 76–80. KUNTZMAN, R. S., R. S. MALEK, and D. M. BARRETT: Highpower potassium titanyl phosphate laser vaporization prostatectomy. Mayo Clin Proc 73, 1998, 798–801. LYNCH, W. J., and J. C. WILLIAMS: Physician’s dialogue: interstitial laser coagulation technique – clinical research updates. World J Urol 18, 2000, suppl 1, 14–15. MACKEY, M. J., C. P. CHILTON, P. J. GILLING, M. FRAUNDORFER and M. D. CRESSWELL: The results of holmium laser resection of the prostate. Br J Urol 81, 1998, 518–519. MALEK, R. S., D. M. BARRETT, and R. S. KUNTZMAN: Highpower potassium-titanyl-phosphate (KTP/532) laser vaporization prostatectomy: 24 hours later. Urology 51, 1998, 254–256. MATSUOKA, K., S. IIDA, K. TOMIYASU, S. SHIMADA, S. SUEKANE, and S. NODA: Holmium laser resection of the prostate. J Endourol 12, 1998, 279–282. MUSCHTER, R., and A. HOFSTETTER: Die interstitielle Laserkoagulation mit dem Diodenlaser der Wellenlänge 830 nm zur Therapie der benignen Prostatahyperplasie – Highversus Low-Volume-Koagulation. Lasermedizin 15, 2000, 72–80. MUSCHTER, R., and H. WHITFIELD: Interstitial laser therapy of benign prostatic hyperplasia. Eur Urol 35, 1999, 147–154. PERLMUTTER, A. P., and R. MUSCHTER: Interstitial laser prostatectomy. Mayo Clin Proc. 73, 1998, 903–907. SCHATZL, G., S. MADERSBACHER, B. DJAVAN, T. LANG, and M. MARBERGER: Two-year results of transurethral resection of the prostate versus four “less invasive” treatment options. Eur Urol 37, 2000, 695–701.
28. SHINGLETON, W. B., J. KOLSKI, D. L. RENFROE, and J. E. FOWLER Jr.: Electrovaporization of the prostate versus laser ablation of the prostate in men with benign prostatic hypertrophy: pressure-flow analysis. Urol Int 60, 1998, 224–228. 29. SHINGLETON, W. B., D. L. RENFROE, J. KOLSKI, and J. E. FOWLER Jr.: A randomized prospective study of transurethral electrovaporization vs laser ablation of the prostate in men with benign prostatic hypertrophy. Scand J Urol Nephrol 32, 1998, 266–269. 30. SHINGLETON, W. B., F. TERRELL, D. L. RENFROE, J. M. KOLSKI, and J. E. FOWLER Jr.: A randomized prospective study of laser ablation of the prostate versus transurethral resection of the prostate in men with benign prostatic hyperplasia. Urology 54, 1999, 1017–1021. 31. SHINGLETON, W. B., F. TERRELL, D. L. RENFROE, J. M. KOLSKI, and J. E. FOWLER Jr.: Low-power v high-power KTP laser: improved method of laser ablation of prostate. J Endourol 13, 1999, 49–52. 32. STEIN, B. S.: Neodymium:yttrium-aluminium-garnet laser prostatectomy. Mayo Clin Proc 73, 1998, 787–791. 33. STEINER, M. S.: Physician’s dialogue: interstitial laser coagulation technique – executive summary. World J Urol 18, 2000, suppl 1, 4–5. 34. TUHKANEN, K., A. HEINO, and M. ALA-OPAS: Contact laser prostatectomy compared to TURP in prostatic hyperplasia smaller than 40 ml. Six-month follow-up with complex urodynamic assessment. Scand J Urol Nephrol 33, 1999, 31–34. 35. TUHKANEN, K., A. HEINO, and M. ALAOPAS: Hybrid laser treatment compared with transurethral resection of the prostate for symptomatic bladder outlet obstruction caused by a large benign prostate: a prospective, randomized trial with a 6-month follow-up. BJU Int 84, 1999, 805–809. 36. WILLIAMS, J. C.: Interstitial laser coagulation of the prostate: introduction of a volume-based treatment formula with 12month follow-up. World J Urol 16, 1998, 392–395. 37. ZORN, B. H.; J. J. BAUER, L. I. E. RUIZ, and J. B. THRASHER: Randomized trial of safety and efficacy of transurethral resection of the prostate using contact laser versus electrocautery. Tech Urol 5, 1999, 198–201.
Correspondence address: Priv.-Doz. Dr. med. Rolf Muschter, Chefarzt der Urologischen Klinik des Diakoniekrankenhauses, Akademisches Lehrkrankenhaus der Universität Göttingen, Elise-Averdieck-Strasse 17, 27356 Rotenburg/Wümme Tel.: ++49-4261-722 361; Fax: ++49-4261-722 136, e-mail: [email protected]
Current Status of Laser Treatment of BPH ROLF MUSCHTER Department of Urology, Diakoniekrankenhaus Rotenburg/Wümme, Germany Submitted: December 2000 · Accepted: January 2001
Summary Several minimally-invasive procedures utilizing laser technology have been introduced in the recent past for the treatment of BPH. Laser treatment of BPH summarizes a variety of techniques using different laser wavelengths, application systems and surgical techniques to achieve contrasting tissue effects such as incision, resection, vaporization, or coagulation. Many studies including randomized trials versus TURP have proven the clinical efficacy of laser treatment of BPH, urodynamic controls confirmed effective unobstruction was achieved. Long-term followup of up to 5 years have demonstrated the durability of the results. Complication rates were much lower compared to TURP, retreatment rates were usually higher than after TURP. Another disadvantage of laser coagulation is an initial increase of obstruction due to the heat associated edema and tissue hardening requiring postoperative catheterization for days or weeks, according to the detrusor function. These problem is not shared by laser vaporization and resection techniques, however, these are difficult to learn, and require usually a long operation time.
Key words Benign prostatic hyperplasia, laser treatment, minimally-invasive therapy, laser coagulation, interstitial laser coagulation, laser resection, laser enucleation, laser vaporization
Introduction During the past 10 years, several so-called minimallyinvasive procedures for the treatment of BPH have been introduced, many of them utilizing laser technology. The term “laser treatment of BPH”, however, summarizes a variety of techniques using different laser wavelengths, application systems and surgical techniques to achieve contrasting tissue effects such as incision, resection, vaporization, or coagulation (Tab.1). All these procedures are based on the same principle: the transmission of laser energy into heat. Dependent on the laser wavelength or its penetration depth, respectively, and the power density, which is a function of laser output power, applicator size or beam divergency and distance between applicator and irradiated surface, and application technique, the resulting tissue effect is either coagulation or vaporization.
Table 1. Laser procedures for the treatment of BPH. transurethral incision of the prostate (TUIP) transurethral ultrasound-guided laser-induced prostatectomy (TULIP) visual/endoscopic laser ablation of the prostate (VLAP, ELAP, LAP) interstitial laser coagulation/thermotherapy (ILK, ILC, LITT, ITT) transurethral laser ablation/evaporization of the prostate (TULAP, TUEP) contact laser vaporization (CLV) transurethral ballon laser thermotherapy (TUBAL-T) holmium laser ablation of the prostate (HoLAP) combined endoscopic laser ablation of the prostate (CELAP) holmium laser resection of the prostate (HoLRP) holmium laser enucleation of the prostate (HoLEP) Nd: YAG/vaportrode laser resection of the prostate 1615–1615/01/16/01-005 $ 15.00/0
6
R. MUSCHTER
Coagulation can be achieved by superficial or interstitial laser application. Vaporization can occur using free beam or contact laser irradiation and can be broad, which is called ablation, or narrow, which is called incision, when the applicator is moved. Two or more incisions connected with each other result in a resection of tissue or enucleation, respectively, if the whole adenoma is removed.
Current Laser Techniques Currently, some laser procedures are only of historical interest. Those being relevant in clinical use are:
Transurethral Laser Coagulation Transurethral laser coagulation, with all synonyms such as visual laser ablation of the prostate (VLAP), side-fire laser, etcetera: In this procedure, the prostate
is irradiated by free beam Nd:YAG or diode laser energy, which is transmitted through a flexible fiber with a deflecting tip to achieve more or less perpendicular irradiation (Fig.1). Depending on the type of applicator used, laser energy is delivered to the urethral surface by “fixed position lasing”, usually using the “four-quadrant technique” with constant laser power and radiation time, or with the laser applicator moved along the surface in a certain way, called “pulling” or “painting”. In any case, the goal of treatment is to achieve deep and homogeneous coagulation necrosis. Consecutively, the necrotized tissue sloughs off within weeks after treatment. The problem with this technique, however, is the unpredictable depth of the lesion really achieved due to superficial carbonization (Fig. 2). If this occurs during the initial phase of laser irradiation, all energy administered consecutively is absorbed by the char preventing any light to penetrate deeper. In most recommended laser schemes with only few treatment sites with fixed radiation times, however, there is no control if and when superficial char occurs and, therefore a lot of tissue may be left untreated without being recognized.
Interstitial laser coagulation
Fig. 1. Visual laser ablation of the prostate.
Fig. 2. Potential surgical failures: intent-to-treat versus real-effect in transurethral laser coagulation of the prostate.
In contrast to the free beam laser irradiation approach, the objective of ILC is to achieve coagulation necrosis inside the adenoma, rather than at its urethral surface (Fig. 3). The interstitial coagulation results in secondary atrophy and regression of the prostatic lobes. This is in contrast to the sloughing of necrotic tissue which occurs after free beam coagulation. Both Nd:YAG and diode lasers can be used for ILC because of their relatively deep penetration in water, efficient volumetric tissue heat loading, and the ability to be delivered through flexible optical fibers. The goal of creating the largest coagulative volume in the shortest amount of surgical time is accomplished by initiating irradiation with a relatively high power to rapidly heat the tissue and coagulate the blood vessels, followed by laser power reduction in order to maintain the temperature in the center of the lesion at a high level just below the carbonization threshold, and allow further lesion expansion. Therefore, the optimal irradiation parameters vary for different laser wavelength and applicator
Current Status of Laser Treatment of BPH
7
Fig. 3. Interstitial laser coagulation of the prostate.
Fig. 4. Temperature feedback control for interstitial laser coagulation.
Fig. 6. Potential surgical failures: intent-to-treat versus real-effect in interstitial laser coagulation.
Fig. 5. Interstitial laser coagulation of the apex of the left side lobe.
combinations. On-line temperature monitoring by an integrated thermocouple allows further optimization by use of a power feedback control (Fig. 4), and optical feedback systems can detect carbonization.
This prevents overheating and fiber damage as well as the tissue char which would limit laser penetration. ILC is usually performed using the transurethral cystoscopic approach (Fig. 5), although the percutaneous perineal approach, in which the laser applicator is introduced through hollow needles in the perineum guided by transrectal ultrasound, is also possible. The learning curve of ILC is short, however, ILC is a surgical technique and requires a correct fiber placement to be successfully performed (Fig. 6).
8
R. MUSCHTER
cator, e.g. the contact probe. Therefore, the volume effect is visible in total. The broader the vaporized area, the more tissue is ablated, the narrower the area of vaporization is, the more a cut results.
Transurethral laser resection or enucleation
Fig. 7. Laser vaporization of the prostate.
Transurethral laser vaporisation For this technique, an Nd:YAG or diode laser is used either with a special contact tip connected to the end of the transmission fiber, or a bare fiber or a common side-firing fiber is used at high laser power settings or high power densities, respectively. Alternatively, the KTP laser with a medium deep tissue penetration is also capable for laser vaporization. Regardless of the wavelength used, tissue effects are alike (Fig. 7): In the initial phase of laser irradiation the tissue water is vaporized, consecutively, the remaining desiccated tissue burns and turns into char. Adjacent to the superficial char is a small layer of coagulation predominantly achieved by heat conduction. The char is either burned at high temperatures by continuing irradiation or mechanically removed by the laser appli-
Transurethral laser resection or enucleation, respectively (Fig. 8): This procedure is similar to a standard transurethral electroresection of the prostate, because the prostate tissue is resected. The procedure is usually performed with a holmium:YAG laser and a bare fiber, but was also done using a Nd:YAG laser with a bare fiber as well as a special contact tip. In holmium laser enucleation of the prostate, two incisions are performed in the 5 and 7 o’clock positions from the bladder neck through to the verumontanum down to the capsule. At the level of the veru, the incisions are connected with each other. The middle lobe is then enucleated in toto by dissecting it from the capsule. The resection starts at the veru and commences towards the bladder until the lobe is finally cut off. Next steps are incisions in the 11 and 1 o’clock positions and a curved incision along the external sphincter on each side to connect the dorsal and ventral incisions, open the plane between the side lobes and the capsule at the apex and begin the enucleation of the side lobes. This is finalized the same way as the middle lobe is resected. Besides a long learning curve to perform the procedure, the problem is to remove the big tissue pieces from the bladder.
Fig. 8. Holmium laser enucleation of the prostate.
Current Status of Laser Treatment of BPH
This usually requires a tissue morcellator, which can cause potential complications, is time consuming and costly. However, because the enucleation is performed in one single plane, there is almost no bleeding during the procedure resulting in a far lower complication rate compared to TURP with the same efficacy as TURP because the tissue is removed completely and immediately.
Clinical Results In the past years, many studies have proven the clinical efficacy of the mentioned laser treatments of BPH including randomized studies versus TURP (8,14,29,30,34,35,37). Urodynamic controls confirmed that an effective unobstruction was achieved (18,28). In recent studies, long-term follow-up of up to 5 years have demonstrated the durability of the results, although in some of the studies, retreatment rates were higher than after TURP.
9
rate of only 1.8% in 57 patients after 36 months, while Schatzl from Marberger’s group (27) in a nonrandomized study reported a retreatment rate of 26.7% after 24 months (Tab. 2). The TURP group required a second operation in 4 %. The improvement of symptoms of the not retreated patients, however, sustained at a high level. Qmax improvement was less pronounced (Fig. 9). Pressure-flow data were analyzed in several studies. In a metaanalysis of the literature, Floratos and de la Rosette (9) demonstrated a significant decrease of obstruction after laser coagulation treatment. The published results, however, are in contrast to the decreasing popularity of the technique. Table 2. Long-term retreatment rate of visual laser ablation of the prostate (3, 6, 27). author
n
follow-up
retreatment
Costello and Kabalin Chertin et al. Schatzl et al.
428 57 15
36 mon 36 mon 24 mon
6.8% 1.8% 26.7%
Transurethral laser coagulation Transurethral laser coagulation, predominantly VLAP, has shown excellent results in past and recent publications (6,32). In newer randomized studies some voiding parameters were improved almost to the level of TURP (8,14,30). Costello and Kabalin (5) reported in long-term follow-up of 428 patients for 24 to 36 months a retreatment rate of 6.8 %. In 20 patients IPSS after 36 months had improved to 5.7 from a baseline of 19.9, and the peak flow rate to 19.7 ml/s from a baseline of 7.7 ml/s. Chertin and coworkers (3) had a retreatment
Interstitial laser coagulation Several studies showing good results of ILC were published in the past (1, 25, 26) (Tab. 3). Most of the recent studies were based on the use of diode lasers (5, 7, 13, 20, 24, 33, 36). These confirm the former results, however, there are contrasting findings. Although symptomatic improvement can be seen in all of the studies, voiding parameters can be improved to a high level or less significant (Tab. 4). Looking on the laser system employed and the technique used, it becomes obvious that two different concepts exist,
Fig. 9. Long-term randomized results of visual laser ablation of the prostate [study of Schatzl et al.: Eur Urol 37, 2000 (27)].
10
R. MUSCHTER
Table 3. ILC: Clinical Results 1994–1997 (25). author
n
IPSS preop
IPSS postop
Qmax preop (ml/s)
Qmax postop (ml/s)
Arai et al. 1996 De la Rosette et al. 1997 Henkel et al. 1995 Horninger et al. 1995 Martov and Kilchukov 1996 McNicholas and Alsudani 1996 Muschter and Hofstetter 1994 Muschter et al. 1995 Muschter et al. 1996a Muschter et al. 1996b Orovan and Whelan 1994 Roggan et al. 1994 Schettini et al. 1996 Whelan 1997 Zhenghua and Cilling 1996
70 25 35 12 25 36 239 48 112 42 16 27 20 112 78
18.9 20.6 21 29 19.9 22 25.4 31.0 20.9 22.1 16.3 14 22.6 18.2 22.5
7.7 6.9 8 6 13.5 7 6.1 2.3 7.9 4.2 5.8 5 9.2 8.2 8.5
6.7 9.1 5.3 8.3 8.7 9.4 7.7 9.4 8.0 8.2 8.8 8.0 7.9 10.4 9.8
10.0 20.3 10.0 16.9 13.5 14.6 17.8 19.7 14.2 24.9 11.9 13.0 15.0 17.0 16.5
Table 4. ILC: Clinical Results Diode Laser 1996–2000 (24). author
n
follow-up (mon)
I-PSS baseline
I-PSS post ILC
Qmax baseline (ml/s)
Qmax post ILC (ml/s)
Conn et al. 1996 Conn et al. 1999 Daehlin/Hedlund 1999 Greenberger/Steiner 1998 Lynch 2000 Martov et al. 1998 Muschter et al. 1996 de la Rosette et al. 1997 Schettini et al. 1996 Williams 1998 Williams 2000
12 165 49 25 39 42 112 25 20 25 165
3 12 12 6 6 24 6 3 3 12 18
22.6 22.4 22 20.2 23.5 23.7 20.9 20.6 22.5 23.2 22.1
6.0 8.3 11 8.8 6.1 9.2 7.9 6.9 8.5 7.2 8.8
7.1 8.6 8.6 8.3 8.4 6.5 8 9.1 7.9 8.4 8.6
14.1 14.2 9.9 14.1 18.4 13.9 14.2 20.3 15.0 16.8 14.6
Fig. 10. Low versus high volume coagulation in ILC.
the low and the high volume approach (Fig. 10). In the high volume coagulation technique, not only symptoms and voiding parameters, but also the prostate volume is significantly reduced (25). A direct comparison of two multicenter studies performed simultaneously with a low volume 830–nm laser, one not randomized and one randomized versus TURP to another study performed later in the same centers using an improved high volume laser demonstrates almost no difference in the symptomatic improvement (Fig. 11). However, the peak flow increase, which is lower than TURP in the low-volume approach, reaches the level of TURP in the high-volume technique (24).
Current Status of Laser Treatment of BPH
11
Fig. 11. Low versus high volume coagulation in ILC: clinical results (24).
Fig. 12. Long-term randomized results of contact laser vaporization of the prostate [study of Keoghane et al.: BJU int 86, 2000 (17)].
Long-term results by use of the Nd:YAG laser ILC in 47 high-risk patients, as reported by Krautschick from Alken’s group (18), showed excellent and sustained results 24 months after ILC in all parameters including pressure-flow studies. The detrusor pressure at Qmax decreased from a baseline of 90 cmH2O to 42 cmH2O, while the prostate volume decreased by an average of 14 ml (18).
Transurethral laser vaporization Recently the 5-year follow-up data of a randomized study comparing contact laser vaporization with TURP have been published (16,17). Within 5 years, 18 % of the laser patients and 14.5 % of the TURP patients required retreatment showing no
significant differences between the two groups. IPSS decreased from 19.5 to 9.7 after laser and from 20.2 to 7.0 after TURP. In both groups, the peak flow rate after 5 years was 14.0 ml/s from a baseline of 12.0 ml/s before laser and 9.0 ml/s before TURP (Fig. 12). For the free beam vaporization technique and the KTP laser, 12-months results were reported recently demonstrating comparable results to the early VLAP or contact laser data (2, 19, 22, 30, 31).
Transurethral laser resection and enucleation In contrast to other laser techniques, most studies employing the holmium laser enucleation technique demonstrate clinical improvement equivalent to
12
R. MUSCHTER
Fig. 13. Randomized clinical results of HoLEP [study of Gilling et al.: J Urol 162, 1999 (12)].
TURP in all clinical parameters at a lower complication rate (4, 10, 15, 21, 23). In single studies, HoLEP is even better than TURP. Studies on big prostates over 60 ml were also published (11). Using a tissue morcellator for tissue removal from the bladder, treatment times become acceptable. Postoperative irrigation, catheterization and hospitalisation was shorter for the laser resection groups. To date, however, only 12 months results are available (12) (Fig. 13). Because the tissue is removed , however, at least theoretically no long-term disadvantage should be expected.
Conclusion Laser treatment of BPH has left its infancy and has matured. For good clinical results, however, the user needs to accept the requirements of success which is proper training. It is not only important to know the basics of lasers and laser-tissue interaction. It is mandatory to understand the procedure, and to use the adequate technology and adequate surgical technique. Limitations of the techniques must be taken into account. In all coagulation techniques, not only those using laser technology, an initial increase of obstruction due to the heat associated edema and tissue hardening must be expected. The volume reduction does not occur immediately, but delayed. This requires postoperative catheterization for days or weeks, according to the detrusor function. These problems are not shared by the laser vaporization and resection techniques. However, these are difficult to learn, and require usually a long operation time.
Aktueller Stand der Laserbehandlung der BPH In den letzten Jahren wurden zahlreiche minimal-invasive Verfahren, die Laserenergie für die Behandlung der BPH einsetzen, vorgestellt. Unter dem Begriff Laserbehandlung der BPH werden verschiedene Techniken zusammengefaßt, denen verschiedene Wellenlängen, Applikationssysteme und chirurgische Verfahren zugrundeliegen und die sehr unterschiedliche Gewebeeffekte, wie Inzision, Resektion, Vaporisation und Koagulation erzielen können. Viele Studien, auch prospektiv gegen die TURP randomisierte, haben die klinische Wirksamkeit der Lasertherapie der BPH gezeigt. Mit Hilfe urodynamischer Untersuchungen konnte gezeigt werden, daß eine wirksame Verringerung der Obstruktion erreicht werden kann. Langzeitbeobachtungen über bis zu 5 Jahre konnten die anhaltende Effektivität zeigen. Die Komplikationsraten waren deutlich geringer, die Wiederbehandlungsrate dagegen in der Regel höher, als bei der TURP. Ein weiterer Nachteil der Laserkoagulation ist die initiale Zunahme der Obstruktion aufgrund hitzebedingter Ödeme und Gewebeverhärtungen, die in Abhängigkeit von der Detrusorfunktion eine postoperative Katheterableitung des Harns für Tage oder Wochen bedingt. Dieses Problem besteht bei der Laservaporisation oder –resektion nicht, diese Verfahren erfordern allerdings eine längere Lernkurve und normalerweise relativ lange Operationszeiten.
Schlüsselwörter Benigne Prostatahyperplasie, Lasertherapie, minimal-invasive Therapie, Laserkoagulation, interstitielle Laserkoagulation, Laserresektion, Laserenukleation, Laservaporisation
References 1. ARAI, Y., K. OKUBO, T. OKADA, S. MAEKAWA, Y. AOKI and H. MAEDA: Interstitial laser coagulation for management of benign prostatic hyperplasia: a Japanese experience. J Urol 159, 1998, 1961–1965. 2. CARTER, A., H. SELLS, M. SPEAKMAN, P. EWINGS, P. O’BOYLE, and R. MACDONAGH: Quality of life changes following
Current Status of Laser Treatment of BPH
3.
4.
5.
6. 7.
8.
KTP/Nd:YAG laser treatment of the prostate and TURP. Eur Urol 36, 1999, 92–98. CHERTIN, B., E. Z. MORIEL, I. HADAS-HALPERIN, W. ABUARAFEH, S. LUPA, M. ZILBERMAN, and A. FARKAS: Laser prostatectomy – long-term follow up of 303 patients. Eur Urol 35, 1999, 285–288. CHILTON C. P., I. P. MUNDY, and O. WISEMAN: Results of holmium laser resection of the prostate for benign prostatic hyperplasia. J Endourol 14, 2000, 533–540. COSTELLO A. J., D. K. AGRARWAL, H. R. CROWE and W. J. LYNCH: Evaluation of interstitial diode laser therapy for treatment of benign prostatic hyperplasia. Tech Urol 5, 1999, 202–206. COSTELLO A. J., and J. N. KABALIN: Side-firing neodymium: yag laser prostatectomy. Eur Urol 35, 1999, 138–146. DAEHLIN, L., and H. HEDLUND: Interstitial laser coagulation in patients with lower urinary tract symptoms from benign prostatic obstruction: treatment under sedoanalgesia with pressure-flow evaluation. BJU Int 84, 1999, 628–636. DONOVAN, J. L., T. J. PETERS, D. E. NEAL, S. T. BROOKES, S. GUJRAL, K. N. CHACKO, M. WRIGHT, L. G. KENNEDY, and P. ABRAMS: A randomized trial comparing transurethal resection of the prostate, laser therapy and conservative treatment of men with symptoms associated with benign prostatic enlargement: the CLasP study. J Urol 164, 2000, 65–70.
13
9. FLORATOS, D. L., and J. J. M. C. H. DE LA ROSETTE: The value of urodynamics in laser prostatectomy. Eur Urol 37, 2000, 509–516. 10. GILLING, P. J., C. B. CASS, A. MALCOLM, M. CRESSWELL, M. R. FRAUNDORFER, and J. N. KABALIN: Holmium laser resection of the prostate versus neodymium: yttrium-aluminiumgarnet visual laser ablation of the prostate: a randomized prospective comparison of two techniques for laser prostatectomy. Urology 51, 1998, 573–577. 11. GILLING P. J., K. M. KENNETT, and M. R. FRAUNDORFER: Holmium laser enucleation of the prostate for glands larger than 100 g: an endourologic alternative to open prostatectomy. J Endourol 14, 2000, 529–530. 12. GILLING, P. J., M. MACKEY, M. CRESSWELL, K. KENNETT, J. N. KABALIN, and M. R. FRAUNDORFER: Holmium laser versus transurethral resection of the prostate: a randomized prospective trial with 1-year followup. J Urol 162, 1999, 1640–1644. 13. GREENBERGER, M., and M. S. STEINER: The University of Tennessee experience with the Indigo 830e laser device for the minimally invasive treatment of benign prostatic hyperplasia: interim analysis: World J Urol 16, 1998, 386–391. 14. GUJRAL, S., P. ABRAMS, J. L. DONOVAN, D. E. NEAL, S. T. BROOKES, K. N. CHACKO, M. J. P. WRIGHT, A. G. TIMONEY,
Anzeige
14
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25. 26. 27.
R. MUSCHTER and T. J. PETERS: A prospective randomized trial comparing transurethral resection of the prostate and laser therapy in men with chronic urinary retention: the CLasP study. J Urol 164, 2000, 59–64. KABALIN, J. N., P. J. GILLING, and M. R. FRAUNDORFER: Holmium-yttrium-aluminium-garnet laser prostatectomy. Mayo Clin Proc. 73, 1998, 792–797. KEOGHANE, S. R., K. C. LAWRENCE, A. M. GRAY, H. A. DOLL, A. M. HANCOCK, K. TURNER, M. E. SULLIVAN, O. DYAR, and D. W. CRANSTON: A double-blind randomized controlled trial and economic evaluation of transurethral resection vs contact laser vaporization for benign prostatic enlargement: a 3-year follow-up. BJU Int 85, 2000, 74–80. KEOGHANE, S. R., M. E. SULLIVAN, H. A. DOLL, J. KOURAMBAS, and D. W. CRANSTON: Five-year data from the Oxford laser prostatectomy trial. BJU Int 86, 2000, 227-228. KRAUTSCHICK, A. W., K. U. KÖHRMANN, T. O. HENKEL, M. S. MICHEL, and P. ALKEN: Interstitial laser coagulation in benign prostatic hyperplasia. A critical evaluation after 2 years of follow-up. Urol Int 62, 1999, 76–80. KUNTZMAN, R. S., R. S. MALEK, and D. M. BARRETT: Highpower potassium titanyl phosphate laser vaporization prostatectomy. Mayo Clin Proc 73, 1998, 798–801. LYNCH, W. J., and J. C. WILLIAMS: Physician’s dialogue: interstitial laser coagulation technique – clinical research updates. World J Urol 18, 2000, suppl 1, 14–15. MACKEY, M. J., C. P. CHILTON, P. J. GILLING, M. FRAUNDORFER and M. D. CRESSWELL: The results of holmium laser resection of the prostate. Br J Urol 81, 1998, 518–519. MALEK, R. S., D. M. BARRETT, and R. S. KUNTZMAN: Highpower potassium-titanyl-phosphate (KTP/532) laser vaporization prostatectomy: 24 hours later. Urology 51, 1998, 254–256. MATSUOKA, K., S. IIDA, K. TOMIYASU, S. SHIMADA, S. SUEKANE, and S. NODA: Holmium laser resection of the prostate. J Endourol 12, 1998, 279–282. MUSCHTER, R., and A. HOFSTETTER: Die interstitielle Laserkoagulation mit dem Diodenlaser der Wellenlänge 830 nm zur Therapie der benignen Prostatahyperplasie – Highversus Low-Volume-Koagulation. Lasermedizin 15, 2000, 72–80. MUSCHTER, R., and H. WHITFIELD: Interstitial laser therapy of benign prostatic hyperplasia. Eur Urol 35, 1999, 147–154. PERLMUTTER, A. P., and R. MUSCHTER: Interstitial laser prostatectomy. Mayo Clin Proc. 73, 1998, 903–907. SCHATZL, G., S. MADERSBACHER, B. DJAVAN, T. LANG, and M. MARBERGER: Two-year results of transurethral resection of the prostate versus four “less invasive” treatment options. Eur Urol 37, 2000, 695–701.
28. SHINGLETON, W. B., J. KOLSKI, D. L. RENFROE, and J. E. FOWLER Jr.: Electrovaporization of the prostate versus laser ablation of the prostate in men with benign prostatic hypertrophy: pressure-flow analysis. Urol Int 60, 1998, 224–228. 29. SHINGLETON, W. B., D. L. RENFROE, J. KOLSKI, and J. E. FOWLER Jr.: A randomized prospective study of transurethral electrovaporization vs laser ablation of the prostate in men with benign prostatic hypertrophy. Scand J Urol Nephrol 32, 1998, 266–269. 30. SHINGLETON, W. B., F. TERRELL, D. L. RENFROE, J. M. KOLSKI, and J. E. FOWLER Jr.: A randomized prospective study of laser ablation of the prostate versus transurethral resection of the prostate in men with benign prostatic hyperplasia. Urology 54, 1999, 1017–1021. 31. SHINGLETON, W. B., F. TERRELL, D. L. RENFROE, J. M. KOLSKI, and J. E. FOWLER Jr.: Low-power v high-power KTP laser: improved method of laser ablation of prostate. J Endourol 13, 1999, 49–52. 32. STEIN, B. S.: Neodymium:yttrium-aluminium-garnet laser prostatectomy. Mayo Clin Proc 73, 1998, 787–791. 33. STEINER, M. S.: Physician’s dialogue: interstitial laser coagulation technique – executive summary. World J Urol 18, 2000, suppl 1, 4–5. 34. TUHKANEN, K., A. HEINO, and M. ALA-OPAS: Contact laser prostatectomy compared to TURP in prostatic hyperplasia smaller than 40 ml. Six-month follow-up with complex urodynamic assessment. Scand J Urol Nephrol 33, 1999, 31–34. 35. TUHKANEN, K., A. HEINO, and M. ALAOPAS: Hybrid laser treatment compared with transurethral resection of the prostate for symptomatic bladder outlet obstruction caused by a large benign prostate: a prospective, randomized trial with a 6-month follow-up. BJU Int 84, 1999, 805–809. 36. WILLIAMS, J. C.: Interstitial laser coagulation of the prostate: introduction of a volume-based treatment formula with 12month follow-up. World J Urol 16, 1998, 392–395. 37. ZORN, B. H.; J. J. BAUER, L. I. E. RUIZ, and J. B. THRASHER: Randomized trial of safety and efficacy of transurethral resection of the prostate using contact laser versus electrocautery. Tech Urol 5, 1999, 198–201.
Correspondence address: Priv.-Doz. Dr. med. Rolf Muschter, Chefarzt der Urologischen Klinik des Diakoniekrankenhauses, Akademisches Lehrkrankenhaus der Universität Göttingen, Elise-Averdieck-Strasse 17, 27356 Rotenburg/Wümme Tel.: ++49-4261-722 361; Fax: ++49-4261-722 136, e-mail: [email protected]