title: Thermocoagulation effect of diode laser radiation in the human prostate: acute and chronic study.
abstract: OBJECTIVE
  To evaluate the safety and efficacy of low-power slow-heating diode laser-induced photocoagulation of prostatic tissue for treatment of benign prostatic hyperplasia, we conducted a series of acute and chronic studies using a diode laser (810 nm) to irradiate human prostate.
  
  
  METHODS
  The study included 6 patients undergoing radical prostatectomy because of malignancy. Laser radiation to the prostate was given transurethrally, in a noncontact mode, at the time of the procedure in 2 patients (acute group): 10 W for 300 seconds on the right side of the prostate and 15 W for 180 seconds on the left. In the remaining 4 patients (chronic group), laser radiation was given at 1, 7, 10, and 12 weeks prior to the prostatectomy.
  
  
  RESULTS
  In the acute group the average depth of coagulation was 8.5 and 9.0 mm for the laser regimens of 15 W for 180 seconds and the 10 W for 300 seconds, respectively. In the chronic group, the average depth of coagulation was 8.9 mm for both laser regimens studied. In the acute group, there was an ill-defined hemorrhagic ring at the periphery of the lesion. At 1 week, an intact necrotic coagulum was present. At 7 weeks, some of the coagulated tissue had already sloughed off. Longer follow-up at 10 and 12 weeks demonstrated formation of a well-defined cavity with mostly re-epithelialized surface.
  
  
  CONCLUSIONS
  Our findings suggest that noncontact diode laser (810 nm) irradiation can induce in the human prostate significant coagulation necrosis followed by sloughing of tissue and cavitation of the prostatic urethra.
authors.affiliation: Department of Surgery, University of Texas Medical Branch, Galveston, USA.
authors.forename: M
authors.initials: M
authors.lastname: Pow-Sang
authors.forename: E
authors.initials: E
authors.lastname: Orihuela
authors.forename: M
authors.initials: M
authors.lastname: Motamedi
authors.forename: J E
authors.initials: JE
authors.lastname: Pow-Sang
authors.forename: D F
authors.initials: DF
authors.lastname: Cowan
authors.forename: R
authors.initials: R
authors.lastname: Dyer
authors.forename: M M
authors.initials: MM
authors.lastname: Warren
mesh_terms: D000368:Aged; D003131:Combined Modality Therapy; D005500:Follow-Up Studies; D006801:Humans; D007430:Intraoperative Care; D017075:Laser Coagulation; D053685:Laser Therapy; D008297:Male; D008875:Middle Aged; D009336:Necrosis; D011300:Preoperative Care; D011467:Prostate / Q000473:pathology; D011468:Prostatectomy / Q000379:methods*; D011471:Prostatic Neoplasms / Q000532:radiotherapy* / Q000601:surgery*; D011879:Radiotherapy Dosage; D013997:Time Factors