Assessment of the learning curves for photoselective vaporization of the prostate using GreenLight™ 180-Watt-XPS laser therapy: Defining the intra-operative parameters within a prospective cohort

Purpose: To assess the learning curves for the intra-operative parameters of the GreenLight™ 180-W XPS for photoselective vaporization of the prostate (PVP). Methods: A prospective study was conducted on 200 men who underwent PVP using the GreenLight™ 180-W XPS over 20 months. The population was divided into four consecutive equal groups. Evolution of lasing parameters was the main endpoint to reach an average energy of 5 kJ per prostate volume and to reach a lasing time/operative time (LT/OT) ratio of 66-80 %. Changes in the IPSS and prostate volume were also evaluated 12 weeks later. Results: Total energy delivered (energy/ml of prostate) and the LT/OT ratio significantly increased over time (p < 0.05). Urinary function significantly improved from baseline in all groups. The first lasing parameter endpoint was reached after the 75th patient (group 1) and the second endpoint (LT/OT ratio) after the 125th patient (group 3). Only the PSA level (p = 0.04) and prostate volume (p < 0.0001) decreased significantly in the 3rd and the 4th group. Post-operative complications occurred in 20 % of patients, which were primarily Clavien-Dindo grades 1 and 2, though there were no statistical differences between the four groups (p = 0.62). In-hospital stay and time to catheter removal were significantly shorter in the 3rd and 4th group. Conclusions: The current study assessed the PVP learning curves within multiple intra-operative parameters. The PVP learning curves required at least 120 procedures until it met all intra-operative parameters of experts in this field.