Holmium:Yttrium-Aluminum-Garnet Laser

The Ho:YAG laser can be used for a variety of methods of treating BPH including holmium enucleation (HoLEP), holmium ablation, and holmium resection of the prostate. The absorption depth in prostatic tissue is 0.4 mm and results in the prostatic tissue being heated to temperatures above 100°C, causing vaporization without deep coagulation. Kuntz and Ahyai have published two separate randomized controlled trials, one comparing HoLEP with transurethral resection of the prostate (TURP) and the other with open prostatectomy. Initially, 100 patients were randomized to either HoLEP or TURP. At 36 months postprocedure peak flow rate (Qmax) and American Urological Association symptom scores were not statistically different between the two groups, whereas postvoid residual was significantly better in the HoLEP group (20.2 versus 8.4 mL). There were no blood transfusions in the HoLEP group versus two transfusions in the TURP group. The HoLEP group also had significantly shorter catheter times (1 day versus 2 days for TURP). Late complications at 36 months were similar. In a further randomized analysis these same authors compared open prostatectomy with HoLEP for prostates greater than 100 g. There was a follow-up period of 5 years; however, 46 patients (38.3%) were lost to follow-up or were excluded. Mean American Urological Association symptom scores, postvoid residual, and Qmax were not significantly different between the two groups at 5-year follow-up. There were no blood transfusions in the HoLEP group versus 13.3% in the open prostatectomy group. Retrospective matched-pair analysis of open prostatectomy and those who had HoLEP with morcellation showed operative times were not significantly different. The number of patients requiring reoperation in the 5-year follow-up period were similar.

Gilling and colleagues reported on their mean of 6-year follow-up with HoLEP, which was derived from patients who were contactable from three previous randomized controlled trials. Seventy-one patients were eligible, and of these 38 patients were available for analysis, 19 could not be located, and 14 had died since their surgery. Outcome measures including International Prostate Symptom Score, quality of life score, and Qmax all showed durable improvement at 6 years postprocedure. One patient required a repeat HoLEP procedure at 5 years and one patient needed an urethrotomy at 6 months. Although limited, these results seem to indicate that HoLEP offers sustained improvement in voiding symptoms up to 6 years. The use of HoLEP in anticoagulated patients was examined by a retrospective review of 83 patients. A total of 14 patients underwent surgery without cessation of anticoagulant and 34 had low-molecular-weight heparin substitution. Mean prostate size was 82.4 g. The blood transfusion rate was 14.2% in the fully anticoagulated patients, 14.7% in the low-molecular-weight heparin substitution group, and 3% in those who temporarily ceased anticoagulation. The retrospective nature of the study and variety of anticoagulants and timing of their cessation make the results difficult to interpret. The blood transfusion rate with HoLEP in this series is less than the 30% transfusion rate reported by Parr and coworkers, however, who examined 12 patients who had TURP without withdrawal of warfarin therapy.

Potassium Titanyl Phosphate and Lithium Triborate Lasers

The KTP and LBO laser are used for photoselective vaporization of the prostate (PVP), with the newer 120-W LBO representing the latest advancement over the older 80-W KTP system. These lasers operate at a wavelength of 532 nm, at which there is maximal absorption by hemoglobin and minimal absorption by water, and remove prostatic tissue by vaporization. There is limited long-term data regarding the 120-W LBO system, with the largest experience being prospective and multicenter from the International Greenlight Laser User group. Their data reported in 2008 are limited by short follow-up (mean, 4.2 months). They found significant improvement in International Prostate Symptom Score, Qmax, and postvoid residual in the subgroups of patients with preoperative urinary retention; on anticoagulants (35 aspirin, 22 warfarin, 13 clopidogrel, 2 on both aspirin and clopidogrel); and those with large prostates (>80 mL). The short follow-up makes it difficult to assess complications, such as urethral stricture or bladder neck stricture.

Intraoperative bleeding complications were evident in seven patients (2.9%) in the no anticoagulation group who required electrocautery to control bleeding, versus one patient (1.5%) in the anticoagulation group. In the early postoperative phase (mean, 12 weeks), there were two patients requiring blood transfusion, whereas two patients needed reoperation for insufficient voiding and 14 patients required recatheterization for urinary retention. The effect of anticoagulants on patients having PVP has also been examined in 116 men on oral anticoagulants (71 on aspirin, 9 on clopidogrel, and 36 on coumarin derivatives) compared with 92 men without anticoagulants. No anticoagulants were ceased at any stage. No patients in either group required a blood transfusion perioperatively.

Spaliviero and colleagues reported on 70 consecutive patients who underwent LBO laser PVP, and further analyzed them on the basis of whether they passed a voiding trial 2 hours postprocedure (catheter negative) or passed a trial of void the following morning (catheter positive). Overall, 49 patients were catheter negative and 21 were catheter positive. No patients failed the postoperative morning trial of void. Overall voiding outcomes in the two groups were improved from baseline out to 24 weeks follow-up. Qmax in the catheter-positive group improved from 8 mL per second at baseline to 21 mL per second at 24 weeks, and in the catheter-negative group improved from 10 mL per second at baseline to 24 mL per second at 24 weeks. Two patients in the catheter-positive group required temporary catheterization within 30 days for acute urinary retention.

The long-term outcomes of the 80-W KTP laser and the initial 60-W prototype have been well reported in the literature, with a number of trials with up to 5-year follow-up demonstrating sustained clinical improvement in symptom scores and urinary flow rates. A nonrandomized comparative trial of the 80-W KTP laser and TURP with up to 24-months follow-up was recently reported by Ruszat and colleagues. Sustained improvements in voiding parameters, which were comparable between the two groups, were noted. There were significantly fewer intraoperative bleeding complications and blood transfusions in the PVP group; however, the PVP group had a higher reoperation rate of 6.7% versus 3.9% for TURP, which did not reach statistical significance on chi-square testing. A second comparative trial of the 80-W KTP laser and TURP was performed by Bouchier-Hayes and colleagues. Of the 44 patients who had 12-month follow-up, there was no significant difference between the two groups regarding International Prostate Symptom Score, Qmax, or postvoid residual volume, although the authors note that the results are preliminary because the study was underpowered.

PVP and holmium ablation of the prostate were compared in a prospective, randomized trial of 109 patients who had lower urinary tract symptoms with a prostate size less than 60 g. After 12-months follow-up, both groups demonstrated significant improvements in International Prostate Symptom Score and Qmax compared with baseline. Hospital stay was 0.8 days in the holmium ablation of the prostate group and 0.9 days in the PVP group. Operative time was significantly longer in the holmium ablation of the prostate group (69.8 versus 55.5 minutes) and there were no major intraoperative complications in either group. A randomized prospective study compared the 80-W KTP laser with transvesical open enucleation for prostatic adenomas greater than 80 mL in size. Of 125 randomized patients there were no differences in International Prostate Symptom Score or Qmax. There were five patients in the PVP group in whom a resectoscope was required to control hemostasis during the procedure. A total of eight patients in the open prostatectomy group required a perioperative blood transfusion, compared with zero patients in the PVP group.

One of the criticisms of PVP and other laser ablative techniques is the lack of tissue for histologic examination. Biers and colleagues reviewed data from the Royal Hampshire County Hospital from 1996 to 2006 and noted that the TURP-detected cancer rate fell from 22% in 1996 to 1997 to 1.5%-5.6% per year from 2001 to 2006. TURP-diagnosed cancers are mainly from the transitional zone and were found to have a mean Gleason score of 5.7. Most TURP-diagnosed cancers were allocated to active surveillance (82%) with 18% started on hormonal therapy. There were no prostate cancer progressions requiring radical prostatectomy or prostate cancer–related deaths in this group over a mean follow-up period of 49.2 months.

Thulium Laser

The thulium laser has a tunable wavelength between 1.75 and 2.22 μm, and for use in the prostate is tuned to a wavelength near the maximal absorption of laser energy into water. This results in high absorption of the laser energy into the prostate and tissue vaporization and a shallow penetration depth. Wendt-Nordahl and colleagues used a 2-μm continuous-wave thulium laser in an ex vivo model using an isolated, blood-perfused porcine kidney. They compared it with TURP and PVP using the 80-W KTP laser. The thulium laser had a faster tissue ablation rate than the KTP laser at 6.56 ± 0.69 g per minute versus 3.99 ± 0.48 g per minute, respectively. The hemostatic properties of the two lasers were similar. In comparison with TURP, the thulium laser had slower tissue ablation but superior hemostatic properties, with bleeding for both the thulium and KTP laser noted to be 100 times less compared with TURP. Clinical studies are limited at this stage; however, a prospective randomized controlled trial of thulium continuous-wave versus Ho:YAG enucleation of the prostate found no differences in efficacy or complication rates at 12 months. Xia and colleagues described the tangerine technique in which the prostatic lobes are dissected off the capsule, yielding tissue for histologic analysis and compared it with TURP. Urodynamic findings and symptom scores at 1 year in both groups showed significant improvement from baseline and were not statistically different. Catheterization time, hospital stay, and hemoglobin drop were all significantly less in the thulium group. Operative time was similar in the two groups. One patient had stress incontinence and one patient had a urethral stricture in the thulium group compared with three urethral strictures in the TURP group.

Semiconductor Diode Lasers

The 980-nm SCD laser uses a wavelength that has the highest simultaneous absorption in hemoglobin and water, which is theorized to provide both hemostatic and ablative properties. Using an ex vivo porcine kidney model, Wendt-Nordahl and colleagues compared a 980-nm SCD laser with TURP and an 80-W KTP laser. The authors found that the SCD laser had a faster tissue ablation rate of 7.24 ± 1.48 g per 10 minutes compared with 3.99 ± 0.48 g per 10 minutes for the KTP laser. TURP had the fastest tissue ablation rate at 8.28 ± 0.38 g per 10 minutes. The bleeding rate for both the SCD laser and the KTP laser was approximately 100 times less than for TURP. A prototype 50-W diode laser prototype operating at wavelength of 1470 nm was trialed in 10 patients with bladder outlet obstruction secondary to BPH. The 1470-nm wavelength is well absorbed by both hemoglobin and water. Based on urodynamic findings and symptom scores, the study concluded that the 1470-nm SCD laser seemed to be feasible and effective for relieving bladder outflow obstruction in BPH, up to the follow-up time of 1 year; however, two patients required TURP within 2 months because they were not satisfied with their outcome.

Holmium:Yttrium-Aluminum-Garnet Laser

The Ho:YAG laser can be used for a variety of methods of treating BPH including holmium enucleation (HoLEP), holmium ablation, and holmium resection of the prostate. The absorption depth in prostatic tissue is 0.4 mm and results in the prostatic tissue being heated to temperatures above 100°C, causing vaporization without deep coagulation. Kuntz and Ahyai have published two separate randomized controlled trials, one comparing HoLEP with transurethral resection of the prostate (TURP) and the other with open prostatectomy. Initially, 100 patients were randomized to either HoLEP or TURP. At 36 months postprocedure peak flow rate (Qmax) and American Urological Association symptom scores were not statistically different between the two groups, whereas postvoid residual was significantly better in the HoLEP group (20.2 versus 8.4 mL). There were no blood transfusions in the HoLEP group versus two transfusions in the TURP group. The HoLEP group also had significantly shorter catheter times (1 day versus 2 days for TURP). Late complications at 36 months were similar. In a further randomized analysis these same authors compared open prostatectomy with HoLEP for prostates greater than 100 g. There was a follow-up period of 5 years; however, 46 patients (38.3%) were lost to follow-up or were excluded. Mean American Urological Association symptom scores, postvoid residual, and Qmax were not significantly different between the two groups at 5-year follow-up. There were no blood transfusions in the HoLEP group versus 13.3% in the open prostatectomy group. Retrospective matched-pair analysis of open prostatectomy and those who had HoLEP with morcellation showed operative times were not significantly different. The number of patients requiring reoperation in the 5-year follow-up period were similar.

Gilling and colleagues reported on their mean of 6-year follow-up with HoLEP, which was derived from patients who were contactable from three previous randomized controlled trials. Seventy-one patients were eligible, and of these 38 patients were available for analysis, 19 could not be located, and 14 had died since their surgery. Outcome measures including International Prostate Symptom Score, quality of life score, and Qmax all showed durable improvement at 6 years postprocedure. One patient required a repeat HoLEP procedure at 5 years and one patient needed an urethrotomy at 6 months. Although limited, these results seem to indicate that HoLEP offers sustained improvement in voiding symptoms up to 6 years. The use of HoLEP in anticoagulated patients was examined by a retrospective review of 83 patients. A total of 14 patients underwent surgery without cessation of anticoagulant and 34 had low-molecular-weight heparin substitution. Mean prostate size was 82.4 g. The blood transfusion rate was 14.2% in the fully anticoagulated patients, 14.7% in the low-molecular-weight heparin substitution group, and 3% in those who temporarily ceased anticoagulation. The retrospective nature of the study and variety of anticoagulants and timing of their cessation make the results difficult to interpret. The blood transfusion rate with HoLEP in this series is less than the 30% transfusion rate reported by Parr and coworkers, however, who examined 12 patients who had TURP without withdrawal of warfarin therapy.

Potassium Titanyl Phosphate and Lithium Triborate Lasers

The KTP and LBO laser are used for photoselective vaporization of the prostate (PVP), with the newer 120-W LBO representing the latest advancement over the older 80-W KTP system. These lasers operate at a wavelength of 532 nm, at which there is maximal absorption by hemoglobin and minimal absorption by water, and remove prostatic tissue by vaporization. There is limited long-term data regarding the 120-W LBO system, with the largest experience being prospective and multicenter from the International Greenlight Laser User group. Their data reported in 2008 are limited by short follow-up (mean, 4.2 months). They found significant improvement in International Prostate Symptom Score, Qmax, and postvoid residual in the subgroups of patients with preoperative urinary retention; on anticoagulants (35 aspirin, 22 warfarin, 13 clopidogrel, 2 on both aspirin and clopidogrel); and those with large prostates (>80 mL). The short follow-up makes it difficult to assess complications, such as urethral stricture or bladder neck stricture.

Intraoperative bleeding complications were evident in seven patients (2.9%) in the no anticoagulation group who required electrocautery to control bleeding, versus one patient (1.5%) in the anticoagulation group. In the early postoperative phase (mean, 12 weeks), there were two patients requiring blood transfusion, whereas two patients needed reoperation for insufficient voiding and 14 patients required recatheterization for urinary retention. The effect of anticoagulants on patients having PVP has also been examined in 116 men on oral anticoagulants (71 on aspirin, 9 on clopidogrel, and 36 on coumarin derivatives) compared with 92 men without anticoagulants. No anticoagulants were ceased at any stage. No patients in either group required a blood transfusion perioperatively.

Spaliviero and colleagues reported on 70 consecutive patients who underwent LBO laser PVP, and further analyzed them on the basis of whether they passed a voiding trial 2 hours postprocedure (catheter negative) or passed a trial of void the following morning (catheter positive). Overall, 49 patients were catheter negative and 21 were catheter positive. No patients failed the postoperative morning trial of void. Overall voiding outcomes in the two groups were improved from baseline out to 24 weeks follow-up. Qmax in the catheter-positive group improved from 8 mL per second at baseline to 21 mL per second at 24 weeks, and in the catheter-negative group improved from 10 mL per second at baseline to 24 mL per second at 24 weeks. Two patients in the catheter-positive group required temporary catheterization within 30 days for acute urinary retention.

The long-term outcomes of the 80-W KTP laser and the initial 60-W prototype have been well reported in the literature, with a number of trials with up to 5-year follow-up demonstrating sustained clinical improvement in symptom scores and urinary flow rates. A nonrandomized comparative trial of the 80-W KTP laser and TURP with up to 24-months follow-up was recently reported by Ruszat and colleagues. Sustained improvements in voiding parameters, which were comparable between the two groups, were noted. There were significantly fewer intraoperative bleeding complications and blood transfusions in the PVP group; however, the PVP group had a higher reoperation rate of 6.7% versus 3.9% for TURP, which did not reach statistical significance on chi-square testing. A second comparative trial of the 80-W KTP laser and TURP was performed by Bouchier-Hayes and colleagues. Of the 44 patients who had 12-month follow-up, there was no significant difference between the two groups regarding International Prostate Symptom Score, Qmax, or postvoid residual volume, although the authors note that the results are preliminary because the study was underpowered.

PVP and holmium ablation of the prostate were compared in a prospective, randomized trial of 109 patients who had lower urinary tract symptoms with a prostate size less than 60 g. After 12-months follow-up, both groups demonstrated significant improvements in International Prostate Symptom Score and Qmax compared with baseline. Hospital stay was 0.8 days in the holmium ablation of the prostate group and 0.9 days in the PVP group. Operative time was significantly longer in the holmium ablation of the prostate group (69.8 versus 55.5 minutes) and there were no major intraoperative complications in either group. A randomized prospective study compared the 80-W KTP laser with transvesical open enucleation for prostatic adenomas greater than 80 mL in size. Of 125 randomized patients there were no differences in International Prostate Symptom Score or Qmax. There were five patients in the PVP group in whom a resectoscope was required to control hemostasis during the procedure. A total of eight patients in the open prostatectomy group required a perioperative blood transfusion, compared with zero patients in the PVP group.

One of the criticisms of PVP and other laser ablative techniques is the lack of tissue for histologic examination. Biers and colleagues reviewed data from the Royal Hampshire County Hospital from 1996 to 2006 and noted that the TURP-detected cancer rate fell from 22% in 1996 to 1997 to 1.5%-5.6% per year from 2001 to 2006. TURP-diagnosed cancers are mainly from the transitional zone and were found to have a mean Gleason score of 5.7. Most TURP-diagnosed cancers were allocated to active surveillance (82%) with 18% started on hormonal therapy. There were no prostate cancer progressions requiring radical prostatectomy or prostate cancer–related deaths in this group over a mean follow-up period of 49.2 months.

Thulium Laser

The thulium laser has a tunable wavelength between 1.75 and 2.22 μm, and for use in the prostate is tuned to a wavelength near the maximal absorption of laser energy into water. This results in high absorption of the laser energy into the prostate and tissue vaporization and a shallow penetration depth. Wendt-Nordahl and colleagues used a 2-μm continuous-wave thulium laser in an ex vivo model using an isolated, blood-perfused porcine kidney. They compared it with TURP and PVP using the 80-W KTP laser. The thulium laser had a faster tissue ablation rate than the KTP laser at 6.56 ± 0.69 g per minute versus 3.99 ± 0.48 g per minute, respectively. The hemostatic properties of the two lasers were similar. In comparison with TURP, the thulium laser had slower tissue ablation but superior hemostatic properties, with bleeding for both the thulium and KTP laser noted to be 100 times less compared with TURP. Clinical studies are limited at this stage; however, a prospective randomized controlled trial of thulium continuous-wave versus Ho:YAG enucleation of the prostate found no differences in efficacy or complication rates at 12 months. Xia and colleagues described the tangerine technique in which the prostatic lobes are dissected off the capsule, yielding tissue for histologic analysis and compared it with TURP. Urodynamic findings and symptom scores at 1 year in both groups showed significant improvement from baseline and were not statistically different. Catheterization time, hospital stay, and hemoglobin drop were all significantly less in the thulium group. Operative time was similar in the two groups. One patient had stress incontinence and one patient had a urethral stricture in the thulium group compared with three urethral strictures in the TURP group.

Semiconductor Diode Lasers

The 980-nm SCD laser uses a wavelength that has the highest simultaneous absorption in hemoglobin and water, which is theorized to provide both hemostatic and ablative properties. Using an ex vivo porcine kidney model, Wendt-Nordahl and colleagues compared a 980-nm SCD laser with TURP and an 80-W KTP laser. The authors found that the SCD laser had a faster tissue ablation rate of 7.24 ± 1.48 g per 10 minutes compared with 3.99 ± 0.48 g per 10 minutes for the KTP laser. TURP had the fastest tissue ablation rate at 8.28 ± 0.38 g per 10 minutes. The bleeding rate for both the SCD laser and the KTP laser was approximately 100 times less than for TURP. A prototype 50-W diode laser prototype operating at wavelength of 1470 nm was trialed in 10 patients with bladder outlet obstruction secondary to BPH. The 1470-nm wavelength is well absorbed by both hemoglobin and water. Based on urodynamic findings and symptom scores, the study concluded that the 1470-nm SCD laser seemed to be feasible and effective for relieving bladder outflow obstruction in BPH, up to the follow-up time of 1 year; however, two patients required TURP within 2 months because they were not satisfied with their outcome.