New photoselective vaporization prostatectomy laser safe, efficacious for lower urinary tract symptoms, according to study

June 1, 2011

Early experience indicates laser photoselective vaporization prostatectomy using the latest generation of a 532-nm lithium triborate laser is a safe, efficacious, and efficient treatment for lower urinary tract symptoms secondary to BPH.

Key Points

Grapevine, TX-Early experience indicates laser photoselective vaporization prostatectomy using the latest generation of a 532-nm lithium triborate laser is a safe, efficacious, and efficient treatment for lower urinary tract symptoms secondary to BPH, according to results presented by researchers from the University of Oklahoma Health Sciences Center, Oklahoma City.

First author Kurt Strom, MD, endourology fellow at the University of Oklahoma Sciences Center, reported intraoperative and postoperative outcomes for a consecutive series of eight men followed for 6 weeks after treatment with the new 180-watt GreenLight XPS laser (American Medical Systems, Minnetonka, MN). Compared with its immediate predecessor (GreenLight HPS), the new laser has a 50% higher power output and an enhanced fiber delivery system (MoXy fiber, American Medical Systems). The eight men had a mean age of 73 years, mean prostate volume of 67.5 mL, and mean PSA of 4.5 ng/mL. Five of them had failed medical therapy, and three were on anticoagulants.

Analysis of intraoperative data showed mean energy was 80 kJ, mean operative time was 24 minutes, and mean laser time was 5.9 minutes, Dr. Strom reported at the American Society for Laser Medicine and Surgery annual meeting in Grapevine, TX. All patients were discharged 3 to 4 hours after the procedure, and six men (75%) went home without a catheter. Catheter removal in the other two men was at 1 day and 1 week post-op, respectively.

With the exception of Sexual Health Inventory for Men scores, all of the objective and subjective outcome measures were significantly improved at 1 week after surgery, and the benefit was durable to last follow-up at 6 weeks. Mean AUA Symptom score was 24.6 at baseline and 7.3 at 1 week, mean maximum flow rate increased from 7.2 mL/s to 18.5 mL/s, and mean postvoid residual urine volume decreased from 322.0 mL to 67.0 mL.

Intraoperatively, there were no technical problems or other complications. Mean hemoglobin and serum sodium were unchanged from baseline after the procedure, and post-treatment morbidity was minimal. Five patients had nonsignificant hematuria, and one man developed a urinary tract infection.

No men required a transfusion or experienced urinary incontinence, and there have been no cases of bladder neck contracture or urethral strictures.

"The preliminary results in this prospective investigation of the enhanced laser reiterate the positive outcomes we reported recently with the 120-watt version for a series of 170 men followed for up to 36 months [Journal of Endourology-in press]," said Dr. Strom, who worked on the study with Carson Wong, MD.

"Now, we are accruing more patients for the present study and will be continuing follow-up in order to see if these promising results are maintained in a larger cohort and over the longer term.

"TURP remains the gold standard treatment for symptomatic BPH, but if it is possible to show this new laser provides equal efficacy after long-term follow-up, it has the potential to create a new paradigm because of its advantages for minimizing morbidity and costs associated with overnight hospitalization," Dr. Strom added.

Fiber delivery system brings enhancements

The new fiber delivery system of the 180-watt laser platform includes several enhancements relative to early versions, including a 50% greater beam area, active saline cooling of the tip that reduces fiber degradation over time, and an integrated temperature monitor that shuts down the laser if the fiber tip overheats. The increased power of the laser and larger beam area combine to result in a near doubling of the power density comparing the 120- and 180-watt lasers (0.28 mm2 vs 0.44 mm2 ), Dr. Strom said.

"As was demonstrated in an animal study [J Urol 2011; 185:712-8], vaporization efficiency calculated as the volume of tissue vaporized per unit of time was also almost doubled using the latest-generation device," Dr. Strom noted.

Vaporization efficiency in the present study will be calculated when data are available from the 3-month follow-up visit, during which men will undergo repeat transrectal ultrasound to determine prostate volume reduction.

Dr. Wong receives consulting fees from American Medical Systems.