Can we predict the outcome of 532 nm laser photoselective vaporization of the prostate? Time to event analysis.

PURPOSE: We evaluated the safety, efficacy and predictability of the long-term outcome of GreenLight™ (532 nm laser) photoselective vaporization of the prostate to treat patients with lower urinary tract symptoms secondary to benign prostatic hyperplasia.

MATERIALS AND METHODS: We performed a longitudinal study of patients who underwent GreenLight (532 nm laser) photoselective vaporization of the prostate at our center between June 2002 and November 2011. All patient data were prospectively maintained in the prostate unit database. Two types of laser equipment were used, including the KTP in 91 cases (31.6%) and the GreenLight HPS™ in 197 (68.4%).

RESULTS: Larger glands were treated with HPS and KTP photoselective vaporization (mean ± SD volume 45.6 ± 22.5 and 39.6 ± 15.2 ml, respectively, p <0.05). After photoselective vaporization with the KTP laser, we noted a 59.1% and 61.8% decrease in the International Prostate Symptom Score, and a 140.7% and 118.4% improvement in the maximal urine flow rate at 1 and 5 years, respectively. Similarly, after prostate vaporization with the HPS we observed a 65.1% and 62.1% decrease in the International Prostate Symptom Score, and a 123.1% and 107.3% improvement in the maximal urine flow rate at 1 and 4 years, respectively. At a mean of 40.5 months (range 3 to 114) of followup reoperation was indicated in 7.6% of cases. The overall rates of bladder neck contracture, de novo urethral stricture and residual/recurrent adenoma were 3.4% (10 cases), 2.1% (6) and 2.1% (6) with no statistically significant difference between vaporization with the KTP and HPS lasers. Most adverse events occurred during year 1 postoperatively. More bladder neck contractures developed after vaporization was done in smaller glands (p <0.05). More cases with residual prostatic adenoma had a prostate volume of 50 ml or greater vs less than 50 ml (4 of 71 or 5.6% vs 2 of 207 or 0.96%).

CONCLUSIONS: GreenLight (532 nm laser) photoselective vaporization of the prostate seems to be safe and effective for lower urinary tract symptoms secondary to benign prostatic hyperplasia. A long lasting, successful outcome is predictable. With careful surveillance during year 1 postoperatively and early intervention for adverse events, a sustainable functional outcome could be achieved without re-treatment.