European Urology

4. Discussion

In a recent review, Cleynenbreugel et al. [8] x B.V. Cleynenbreugel, S.J. Srirangam, H. Van Poppel. High performance system GreenLight laser: indications and outcomes. Current Opin Urol. 2009;19:33-37 looked at four prospective studies 5 x A. Bachmann, L. Schürch, R. Ruszat, et al. Photoselective vaporization (PVP) versus transurethral resection of prostate (TURP): a prospective bi-center study of perioperative morbidity and early functional outcome. Eur Urol. 2005;48:965-972 Abstract, Full-text, PDF, Crossref. , 6 x D.M. Bouchier-Hayes, P. Anderson, S. Van Appledorn, P. Bugeja, A.J. Costello. KTP laser versus transurethral resection of prostate: early results of a randomized trial. J Endourol. 2006;20:580-585 Crossref. , 12 x K. Horasanli, M.S. Silay, B. Altay, et al. Photoselective potassium titanyl phosphate (KTP) laser vaporization versus transurethral resection of the prostate for prostate larger than 70 ml: a short-term prospective randomized trial. Urology. 2008;71:247-251 Crossref. , and 13 x R. Ruszat, S. Wyer, M. Seitz, et al. Comparison of potassium-titanyl-phosphate laser vaporization of the prostate and transurethral resection of the prostate: update of a prospective non-randomized two-centre study. BJU Int. 2008;102:1432-1438 comparing GLL PVP with TURP. The outcome parameters of GLL PVP and TURP were significantly improved when compared with preoperative values, with no significant difference between the two groups 5 x A. Bachmann, L. Schürch, R. Ruszat, et al. Photoselective vaporization (PVP) versus transurethral resection of prostate (TURP): a prospective bi-center study of perioperative morbidity and early functional outcome. Eur Urol. 2005;48:965-972 Abstract, Full-text, PDF, Crossref. , 6 x D.M. Bouchier-Hayes, P. Anderson, S. Van Appledorn, P. Bugeja, A.J. Costello. KTP laser versus transurethral resection of prostate: early results of a randomized trial. J Endourol. 2006;20:580-585 Crossref. , and 12 x K. Horasanli, M.S. Silay, B. Altay, et al. Photoselective potassium titanyl phosphate (KTP) laser vaporization versus transurethral resection of the prostate for prostate larger than 70 ml: a short-term prospective randomized trial. Urology. 2008;71:247-251 Crossref. . Moreover, patients undergoing TURP experienced more severe adverse effects as compared with GLL PVP patients, thus giving the latter a more favorable perioperative safety profile.

The present study, to the best of our knowledge, is the first RCT comparing 120-W GLL PVP versus TURP with a long-term follow-up of 36 mo. Twelve patients (20%) in the TURP group developed significant bleeding, confirming the previous observation that bleeding is a major complication after TURP often requiring transfusion. Clot retention may occur as a consequence as well as premature termination of procedure, with consequent inadequate relief of obstruction. The PVP laser causes very little bleeding and has been used successfully in patients on anticoagulant therapy 1 x H. Woo, O. Reich, A. Backman, et al. Outcome of GreenLight HPS 120-W laser therapy in specific patient populations: those in retention, on anticoagulants, and with large prostate (≥80 ml). Eur Urol Suppl. 2008;7:378-383 Abstract, Full-text, PDF, Crossref. , and 14 x R. Sandhu, C.K. Ng, R.R. Gonzalez, S.A. Kaplan, A.E. Te. Photoselective laser vaporization prostatectomy in men receiving anticoagulants. J Endourol. 2005;19:1196-1198 . Performing conventional TURP in patients who are on oral anticoagulant therapy has a high complication rate with a transfusion rate of 30% [8] x B.V. Cleynenbreugel, S.J. Srirangam, H. Van Poppel. High performance system GreenLight laser: indications and outcomes. Current Opin Urol. 2009;19:33-37 . Usually the patient is commenced on low-molecular-weight heparin preoperatively as bridging therapy. This, however, is associated with longer hospital stay and catheterization time [8] x B.V. Cleynenbreugel, S.J. Srirangam, H. Van Poppel. High performance system GreenLight laser: indications and outcomes. Current Opin Urol. 2009;19:33-37 .

Three patients in the TURP group also experienced TUR syndrome during surgery, an incidence of 5%, which is higher than the 2% proportion reported by Han [15] x R.G. Han. Smoking increases the risk of large-scale fluid absorption during transurethral prostatic resection. J Urol. 2001;166:162-165 . In contrast, none of the patients in the PVP group developed significant change in the hemoglobin or sodium levels compared with the preoperative levels, an advantage of PVP over TURP. This could be explained by the fact that PVP uses saline as an irrigant, thus almost removing the risk of TUR syndrome.

The laser is fully transmitted through the aqueous irrigant but is highly absorbed by oxyhemoglobin in the tissue. This allows the laser energy to be selectively absorbed by tissue with high oxyhemoglobin content, such as prostatic tissue. This results in vaporization that is focused and the short optical penetration at this wavelength confines high-power laser energy to a superficial layer of prostatic tissue with only 1–2 mm of coagulation with optimum technique 9 x D.M. Bouchier-Hayes, S.V. Van Appledorn, P. Bugeja, H. Crowe, B. Challacombe, A.J. Costello. A randomized trial of photoselective vaporization of the prostate using the 80-W potassium titanyl phosphate laser vs transurethral prostatectomy, with 1 year follow-up. BJU Int. 2010;105:964-969 Crossref. , and 16 x R. Lee, R.R. Gonzalez, A.E. Te. The evolution of photoselective vaporization prostatectomy (PVP): advancing the surgical treatment of benign prostatic hyperplasia. World J Urol. 2006;24:405-409 Crossref. . This explains the fact that perforation of the capsule occurred in none of our patients in the PVP group compared with 10 patients in the TURP group. In a recent update, significantly lower rates of intraoperative bleeding, blood transfusion, capsular perforation, and early postoperative clot retention were reported in the GLL PVP group as compared with the TURP group [13] x R. Ruszat, S. Wyer, M. Seitz, et al. Comparison of potassium-titanyl-phosphate laser vaporization of the prostate and transurethral resection of the prostate: update of a prospective non-randomized two-centre study. BJU Int. 2008;102:1432-1438 .

The cost issue was not calculated in the present study. Nevertheless, the high initial and maintenance cost of laser therapy may be partially compensated by the shorter hospital stay and the more rapid return to work. Goh and Gonzalez recently studied the cost of laser PVP versus TURP and concluded that the former procedure has a lower cost [17] x A.C. Goh, R.R. Gonzalez. Photoselective laser vaporization prostatectomy versus transurethral prostate resection: a cost analysis. J Urol. 2010;183:1469-1473 Crossref. . Another concern of PVP is the significantly higher incidence of storage bladder symptoms. These symptoms, however, almost disappear 1 mo after surgery.

There is some concern regarding the long-term reoperation rate with PVP. There are few long-term studies available at present, and none is in the setting of a randomized trial. In the multicenter trial from the United States, the reoperation rate at 3 yr was 4.3% [18] x A.E. Te, T.R. Malloy, B.S. Stein, J.C. Ulchaker, U.O. Nseyo, M.A. Hai. Impact of prostate specific antigen level and prostate volume as predictors of efficacy in photoselective vaporization prostatectomy: analysis and results of an ongoing prospective multicenter study at 3 years. BJU Int. 2006;97:1229-1233 Crossref. . In a recent study, Ruszat et al. [19] x R. Ruszat, M. Seitz, S.F. Wyler, et al. GreenLight laser vaporization of the prostate: single-center experience and long-term results after 500 procedures. Eur Urol. 2008;54:893-901 Abstract, Full-text, PDF, Crossref. reported the long-term results of 500 patients who underwent 80-W PVP. The retreatment rate was 6.8%. Urethral and bladder neck strictures were observed in 4.4% and 3.6%, respectively [19] x R. Ruszat, M. Seitz, S.F. Wyler, et al. GreenLight laser vaporization of the prostate: single-center experience and long-term results after 500 procedures. Eur Urol. 2008;54:893-901 Abstract, Full-text, PDF, Crossref. . In the present series, the reoperation rate in the PVP group was 11% over 36 mo. Notably, the prostate size in all redo cases was >80 g. Therefore, we do not recommend doing PVP for prostate >80 g at the present time. Nevertheless, with increasing experience it would be expected that more tissue would be vaporized.

Long-term functional results showed dramatic improvement in both groups regarding reduction of IPSS and PVR and improvement of Q_max, with no significant difference between both groups. Nevertheless, the percentage reductions in prostate size and PSA were significantly higher in the TURP group. This could be explained by greater resection of transitional zone among the TURP group due to different degrees of experience among the surgeons. This difference is expected to disappear with increasing experience and confidence with PVP in the future. In a recent update, Cleynenbreugel et al. [8] x B.V. Cleynenbreugel, S.J. Srirangam, H. Van Poppel. High performance system GreenLight laser: indications and outcomes. Current Opin Urol. 2009;19:33-37 compared the long-term functional outcome of GLL PVP and TURP. The improvement in Q_max was greater following the TURP. The change in IPSS and PVR volumes postoperatively was similar in both groups. After 12 mo, the overall reduction in prostate size was 60% after TURP and 48% after GLL PVP. The rate of repeat TURP/PVP procedures within a 2-yr follow-up period was higher in the GLL PVP group (11% vs 1.9%). Although this was statistically significant, the incidences of urethral and bladder neck stricture formations were comparable [8] x B.V. Cleynenbreugel, S.J. Srirangam, H. Van Poppel. High performance system GreenLight laser: indications and outcomes. Current Opin Urol. 2009;19:33-37 .

One of the limitations of the present study is the drop-out rate of 9.2%. Moreover, the surgical procedures were carried out by urologists with differing amounts of experience, which may explain the relatively high transfusion and perforation rates in the TURP group. In addition, sexual function was not properly assessed via sexual health questionnaires before and after the procedures. Furthermore, observers were not blinded to the group assignment. Therefore, the highly significant statistical difference between the two groups should be cautiously interpreted.