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Re: Chen et al.: Preliminary Results of Prostate Vaporization in the Treatment of Benign Prostatic Hyperplasia by Using a 200-W High-intensity Laser (Urology 2010;75:658-663)
mentioned in the comment, the limitation of endoscopic evaluation is based on the operator’s individual judgment. There are no general accepted classifications or grading systems for the endoscopic evaluation, which are used objectively and consistently to assess the severity of prostate lobes. Furthermore, endoscopic findings “favorable” for TURP might not be ruled out as an indication for TVP. From these standpoints, we did not incorporate these endoscopic findings into our investigation. The conclusion that TVP is superior to TURP is based on the following observations: IPSS, Qmax., Qols, and PVR. We do not jump to the conclusion that the more the resected gland, the better the outcome. Theoretically, more residual prostate adenoma may cause incomplete bladder outlet obstruction, and additional drugs may be used for further reduction of the residual. In other words, incomplete resection of the prostate might aggravate the economic burden on these patients. It is challenging to do TURP on prostates larger than 80 mL. It is possible that even in the hands of experienced physicians, incomplete resection of the prostate still happen in certain situations. Some physicians pointed out that TURP could achieve good or equivalent results by developing a voiding channel without complete removal of adenoma. In our practice, we prefer to remove the adenoma as much as possible. One limitation of the study is that longer-term follow-up is needed to strengthen the power of our conclusion. HoLEP may be a valid alternative to TURP as a new gold standard regardless of the prostate volume and offers satisfactory and durable results with a low rate of longterm complications.3 It may allow for adenoma removal comparable with that of open prostatectomy. However, to date, HoLEPs are not widely performed in some countries. We may adopt this comparison (HoLEP vs TVP) in our future study. Rubiao Ou, M.D. Meng You, M.D. Ping Tang, M.D. Hui Chen, M.D. Xiangrong Deng, M.D. Keji Xie, M.D. Department of Urology Guangzhou First Municipal People’s Hospital Guangzhou Medical College Guangzhou, China References 1. Walsh PC, Retik AB, Vauthan ED, et al. Campbell’s Urology, Vol 2. 7th ed. Philadelphia, Pennsylvania: W. B. Saunders; 2001:15141517. 2. Madersbacher S, Alivizatos G, Nordling J, et al. EAU 2004 guidelines on assessment, therapy and follow-up of men with lower urinary tract symptoms suggestive of benign prostatic obstruction (BPH guidelines). Eur Urol. 2004;46(5):547-554. 3. Suardi N, Gallina A, Salonia A, et al. Holmium laser enucleation of the prostate and holmium laser ablation of the prostate: indications and outcome. Curr Opin Urol. 2009;19(1):38-43.
UROLOGY 77 (3), 2011
Re: Chen et al.: Preliminary Results of Prostate Vaporization in the Treatment of Benign Prostatic Hyperplasia by Using a 200-W High-intensity Laser (Urology 2010;75:658-663) TO THE EDITOR:
We have thus far been comfortable using conventional monopolar transurethral resection of the prostate (TURP) and immensely satisfied with the results. The results of this study by Chien-Hsu Chen et al, and an earlier one show that the diode laser may be a promising alternative to TURP and other laser technologies.1 We respond to this study after having recently used the diode laser at lower power (120 W) setting in 3 cases with a demonstration machine. Our results were not ideal because of the inevitable learning curve for the new technology but we did experience a few technical intraoperative problems unrelated to our inexperience that we would like to share with our readers. 1. The diode laser vaporizes without significant charring of tissues, but a peculiar problem we experienced was that the superficial mucosal and submucosal tissues vaporized easily, whereas the deeper gland tissue vaporized much more slowly. We did follow the instructions to keep the fiber tip just away from the tissue. We had to do a conventional re-TURP for postoperative retention in one of the cases, during which we found that the loop traversed the tissues with difficulty, even at higher cautery settings, indicating denaturation and coagulation of the residual deep tissues by the previous procedure. In short, the efficiency progressively declined as vaporization progressed deeper. The argument in favor of this technology may be that in electrocautery too, power settings have to be increased as resection nears the capsule. 2. The procedure was indeed much too slow for our comfort compared with conventional TURP. A reasonably open channel was what we achieved after an hour of vaporization in our 3 cases but was insufficient for free voiding in two. The residual tissue removed by a subsequent TURP was considerable. 3. Using the diode laser fiber effectively and safely at the apex of the prostate is indeed a daunting task. By safety, we mean the safety of the sphincter as well as that of the telescopic lens. The side firing fiber necessarily has to be extended well ahead of the lens tip to avoid damage during firing. This results in a tricky situation while resecting apical tissue, because the external sphincter contracts around the middle of the protruding fiber, effectively placing the firing end out of sight (Fig. 1A). 765
Figure 1. Relationship between cystoscope tip, the laser fiber firing end and the apical prostatic tissue. (A) Firing end in position but obscured by external sphincter. (B) Scope in position but firing end beyond the prostate apex. (C) Withdrawal of the fibre bringing the firing end dangerously close to the lens tip.
Pushing the scope just above the sphincter would make the apical tissue inaccessible (Fig. 1B). Withdrawal of the fiber closer to the scope tip would place the lens at risk (Fig. 1C). It would be interesting to know whether such a problem was faced by the authors and how it was surmounted. An unbevelled sheath may be useful here. We commend the authors for their good results but would nonetheless rely on TURP by electrocautery until our concerns with this equipment are addressed. Sunil P. Shenoy, M.S., D.N.B., M.Ch., D.N.B. Prashanth K. Marla, M.Ch. Division of Urology, A. J. Institute of Medical Sciences Karnataka, India Thrivikrama Padur Tantry, M.D. Department of Anesthesia, A. J. Institute of Medical Sciences Karnataka, India Reference 1. Erol A, Cam K, Tekin A, et al. High power diode laser vaporization of the prostate: preliminary results for benign prostatic hyperplasia. J Urol. 2009;182:1078-1082.
Re: Li et al.: XRCC3 T241M Polymorphism and Bladder Cancer Risk: A Meta-analysis (Urology 2010;77: 511) TO THE EDITOR:
We read with great interest the recent paper by Li et al.1 They performed a meta-analysis of 16 case-control studies (5298 cases and 6614 controls) to evaluate the role of the X-ray repair cross complementing group 3 (XRCC3) 766
T241M polymorphism in bladder cancer susceptibility. The results of the meta-analysis suggest an increased risk role of XRCC3 241 MM genotype in bladder cancer among all subjects. Nevertheless, several issues seem worth comment. Firstly, meta-analysis should include as much information as possible. However, in the study, the authors only searched reports published from May 2001 to February 2010 in the PubMed database. Hence, it is possible that some studies that meet the inclusion criteria were not included in the meta-analysis. Database bias and publication bias may distort the results of the meta-analysis. Secondly, when there are multiple studies, including overlapping data from the same population, only the largest study should be included in the meta-analysis. In the study, 2 studies by Andrew et al2,3 contained overlapping data in the UK population. Meanwhile, 2 studies by Matullo et al4,5 contained overlapping data in the Italian population. Overlapping data in the 4 studies should be excluded from the meta-analysis. Unfortunately, the authors did not exclude the overlapping data, which may be distorting the current results. Thirdly, multiple (4) comparisons were performed in the article, and the authors should adjust the significance alpha level. The Bonferroni method could be used to adjust the significance alpha level. The usual significance level (␣ ⫽ 0.05) was divided by 4 to account for 4 comparisons. Thus, a P value less than 0.0125 should be considered statistically significant. After correcting for the problem of multiple comparisons, XRCC3 241 MM genotype was not a significant risk factor for developing bladder cancer. Finally, close inspection of the data provided by the authors (Table 2) revealed that the data reported by Li et al for the study by Stern et al6 was not in line with the data provided by Stern et al in their original publication. The numbers reported by Li et al for Thr/Thr and Thr/ Met ⫹ Met/Met in cases and controls, respectively, were UROLOGY 77 (3), 2011
UROLOGY 77 (3), 2011
Re: Chen et al.: Preliminary Results of Prostate Vaporization in the Treatment of Benign Prostatic Hyperplasia by Using a 200-W High-intensity Laser (Urology 2010;75:658-663) TO THE EDITOR:
We have thus far been comfortable using conventional monopolar transurethral resection of the prostate (TURP) and immensely satisfied with the results. The results of this study by Chien-Hsu Chen et al, and an earlier one show that the diode laser may be a promising alternative to TURP and other laser technologies.1 We respond to this study after having recently used the diode laser at lower power (120 W) setting in 3 cases with a demonstration machine. Our results were not ideal because of the inevitable learning curve for the new technology but we did experience a few technical intraoperative problems unrelated to our inexperience that we would like to share with our readers. 1. The diode laser vaporizes without significant charring of tissues, but a peculiar problem we experienced was that the superficial mucosal and submucosal tissues vaporized easily, whereas the deeper gland tissue vaporized much more slowly. We did follow the instructions to keep the fiber tip just away from the tissue. We had to do a conventional re-TURP for postoperative retention in one of the cases, during which we found that the loop traversed the tissues with difficulty, even at higher cautery settings, indicating denaturation and coagulation of the residual deep tissues by the previous procedure. In short, the efficiency progressively declined as vaporization progressed deeper. The argument in favor of this technology may be that in electrocautery too, power settings have to be increased as resection nears the capsule. 2. The procedure was indeed much too slow for our comfort compared with conventional TURP. A reasonably open channel was what we achieved after an hour of vaporization in our 3 cases but was insufficient for free voiding in two. The residual tissue removed by a subsequent TURP was considerable. 3. Using the diode laser fiber effectively and safely at the apex of the prostate is indeed a daunting task. By safety, we mean the safety of the sphincter as well as that of the telescopic lens. The side firing fiber necessarily has to be extended well ahead of the lens tip to avoid damage during firing. This results in a tricky situation while resecting apical tissue, because the external sphincter contracts around the middle of the protruding fiber, effectively placing the firing end out of sight (Fig. 1A). 765
Figure 1. Relationship between cystoscope tip, the laser fiber firing end and the apical prostatic tissue. (A) Firing end in position but obscured by external sphincter. (B) Scope in position but firing end beyond the prostate apex. (C) Withdrawal of the fibre bringing the firing end dangerously close to the lens tip.
Pushing the scope just above the sphincter would make the apical tissue inaccessible (Fig. 1B). Withdrawal of the fiber closer to the scope tip would place the lens at risk (Fig. 1C). It would be interesting to know whether such a problem was faced by the authors and how it was surmounted. An unbevelled sheath may be useful here. We commend the authors for their good results but would nonetheless rely on TURP by electrocautery until our concerns with this equipment are addressed. Sunil P. Shenoy, M.S., D.N.B., M.Ch., D.N.B. Prashanth K. Marla, M.Ch. Division of Urology, A. J. Institute of Medical Sciences Karnataka, India Thrivikrama Padur Tantry, M.D. Department of Anesthesia, A. J. Institute of Medical Sciences Karnataka, India Reference 1. Erol A, Cam K, Tekin A, et al. High power diode laser vaporization of the prostate: preliminary results for benign prostatic hyperplasia. J Urol. 2009;182:1078-1082.
Re: Li et al.: XRCC3 T241M Polymorphism and Bladder Cancer Risk: A Meta-analysis (Urology 2010;77: 511) TO THE EDITOR:
We read with great interest the recent paper by Li et al.1 They performed a meta-analysis of 16 case-control studies (5298 cases and 6614 controls) to evaluate the role of the X-ray repair cross complementing group 3 (XRCC3) 766
T241M polymorphism in bladder cancer susceptibility. The results of the meta-analysis suggest an increased risk role of XRCC3 241 MM genotype in bladder cancer among all subjects. Nevertheless, several issues seem worth comment. Firstly, meta-analysis should include as much information as possible. However, in the study, the authors only searched reports published from May 2001 to February 2010 in the PubMed database. Hence, it is possible that some studies that meet the inclusion criteria were not included in the meta-analysis. Database bias and publication bias may distort the results of the meta-analysis. Secondly, when there are multiple studies, including overlapping data from the same population, only the largest study should be included in the meta-analysis. In the study, 2 studies by Andrew et al2,3 contained overlapping data in the UK population. Meanwhile, 2 studies by Matullo et al4,5 contained overlapping data in the Italian population. Overlapping data in the 4 studies should be excluded from the meta-analysis. Unfortunately, the authors did not exclude the overlapping data, which may be distorting the current results. Thirdly, multiple (4) comparisons were performed in the article, and the authors should adjust the significance alpha level. The Bonferroni method could be used to adjust the significance alpha level. The usual significance level (␣ ⫽ 0.05) was divided by 4 to account for 4 comparisons. Thus, a P value less than 0.0125 should be considered statistically significant. After correcting for the problem of multiple comparisons, XRCC3 241 MM genotype was not a significant risk factor for developing bladder cancer. Finally, close inspection of the data provided by the authors (Table 2) revealed that the data reported by Li et al for the study by Stern et al6 was not in line with the data provided by Stern et al in their original publication. The numbers reported by Li et al for Thr/Thr and Thr/ Met ⫹ Met/Met in cases and controls, respectively, were UROLOGY 77 (3), 2011