title: Assessment of energy density usage during 180W lithium triborate laser photoselective vaporization of the prostate for benign prostatic hyperplasia. Is there an optimum amount of kilo-Joules per gram of prostate?
abstract: To assess the effect of energy density (kJ/mL) applied on adenoma during photoselective vaporization of the prostate (PVP) treatment for benign prostate hyperplasia (BPH) on functional outcomes, prostate-specific antigen (PSA) reduction and complications.
  
  
  
  After exclusions, a total of 440 patients who underwent GreenLight (tm) laser XPS-180W lithium triborate PVP for the treatment of BPH were retrospectively reviewed. Data were collected from seven different international centres (Canada, USA, UK and France). Patients were stratified into four energy density groups (kJ/mL) according to intra-operative energy delivered and prostate volume as determined by preoperative transrectal ultrasonography (TRUS): group 1: <3 kJ/mL; group 2: 3-5 kJ/mL; group 3: 5-7 kJ/mL; and group 4: ≥7 kJ/mL. Energy density groups were chosen arbitrarily. PSA reduction and functional outcomes (International Prostate Symptom Score, quality of life, post-void residual urine volume, maximum urinary flow rate) were compared at 6, 12 and 24 months. Peri-operative complications and retreatment rates were also compared among the groups.
  
  
  
  The PSA reduction rates at 24 months after the procedure were 51, 61, 79 and 83% for the energy density groups <3, 3-5, 5-7 and ≥7 kJ/mL, respectively (P ≤ 0.01). This held true after accounting for baseline confounders. Energy density was not associated with higher complication rates, including haematuria, stricture formation, incontinence, refractory urinary retention, urinary tract infection and conversion to transurethral resection of the prostate. Functional outcomes at 2 years of follow-up were equivalent among the groups (P > 0.05 for all) and similar retreatment rates were observed (P = 0.36).
  
  
  
  Higher energy usage per cc of prostate was associated with a more significant reduction in PSA level (>50%) at 6, 12 and 24 months, suggesting increased vaporization of adenoma tissue; however, this did not translate into differences in functional outcomes at 2-year follow-up.
authors.affiliation: Division of Urology, Centre Hospitalier de l'Université de Montréal (CHUM), Montreal, QC, Canada.
authors.forename: Roger
authors.initials: R
authors.lastname: Valdivieso
authors.affiliation: Division of Urologic Surgery and Center for Surgery and Public Health, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Christian P
authors.initials: CP
authors.lastname: Meyer
authors.affiliation: Division of Urology, Centre Hospitalier de l'Université de Montréal (CHUM), Montreal, QC, Canada.
authors.forename: Pierre-Alain
authors.initials: PA
authors.lastname: Hueber
authors.affiliation: Division of Urology, Centre Hospitalier de l'Université de Montréal (CHUM), Montreal, QC, Canada.
authors.forename: Malek
authors.initials: M
authors.lastname: Meskawi
authors.affiliation: Division of Urology, Centre Hospitalier de l'Université de Montréal (CHUM), Montreal, QC, Canada.
authors.forename: Abdullah M
authors.initials: AM
authors.lastname: Alenizi
authors.affiliation: Division of Urology, Centre Hospitalier de l'Université de Montréal (CHUM), Montreal, QC, Canada.
authors.forename: Mounsif
authors.initials: M
authors.lastname: Azizi
authors.affiliation: Division of Urologic Surgery and Center for Surgery and Public Health, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Quoc-Dien
authors.identifier: 0000-0003-3857-9276
authors.initials: QD
authors.lastname: Trinh
authors.affiliation: Department of Urology, Clinique Pasteur Toulouse, Toulouse, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Misrai
authors.affiliation: Department of Urology, Columbia University, New York, NY, USA.
authors.forename: Matthew
authors.initials: M
authors.lastname: Rutman
authors.affiliation: Department of Urology, Cornell University, New York, NY, USA.
authors.forename: Alexis E
authors.initials: AE
authors.lastname: Te
authors.affiliation: Department of Urology, Cornell University, New York, NY, USA.
authors.forename: Bilal
authors.initials: B
authors.lastname: Chughtai
authors.affiliation: Department of Urology, Frimley Park Hospital, Frimley, Surrey, UK.
authors.forename: Neil J
authors.initials: NJ
authors.lastname: Barber
authors.affiliation: Department of Urology, Frimley Park Hospital, Frimley, Surrey, UK.
authors.forename: Amr M
authors.initials: AM
authors.lastname: Emara
authors.affiliation: Department of Urology, Hackensack University Medical Center, Hackensack, NJ, USA.
authors.forename: Ravi
authors.initials: R
authors.lastname: Munver
authors.affiliation: Division of Urology, Centre Hospitalier de l'Université de Montréal (CHUM), Montreal, QC, Canada. zorn.chumurology@gmail.com.
authors.forename: Kevin C
authors.initials: KC
authors.lastname: Zorn
mesh_terms: D000368:Aged; D001881:Borates; D004736:Energy-Generating Resources; D006801:Humans; D053685:Laser Therapy / Q000379:methods*; D018020:Lithium Compounds; D008297:Male; D008875:Middle Aged; D009929:Organ Size; D011467:Prostate / Q000473:pathology; D011470:Prostatic Hyperplasia / Q000473:pathology / Q000601:surgery*; D012189:Retrospective Studies; D020728:Transurethral Resection of Prostate / Q000379:methods*
chemical_list: D001881:Borates; D018020:Lithium Compounds; C021051:lithium borate
keywords: GreenLight; benign prostate hyperplasia; energy; lithium triborate; photoselective vaporization; prostate-specific antigen reduction