HISTOPATHOLOGICAL EVALUATION OF LASER THERMOCOAGULATION IN THE HUMAN PROSTATE - OPTIMIZATION OF LASER IRRADIATION FOR BENIGN PROSTATIC HYPERPLASIA

We have previously shown in a canine prostate model that a noncontact low power neodymium: YAG laser regimen of 15 watts for 180 seconds yie lds a larger volume of coagulation necrosis than the currently recomme nded high power regimen of 50 watts for 60 seconds. These 2 regimens h ave not yet been compared in humans. The objective of this study was t o evaluate histopathologically the thermocoagulation effect of these 2 laser regimens in the human prostate and the effect of the spatial di stribution of the laser lesions on the extent of coagulation necrosis. The study was conducted in 10 patients undergoing radical prostatecto my or cystoprostatectomy. The laser treatment was given transurethrall y 1 hour before removal of the specimen. There were no fractures of th e prostate. The coagulation necrosis did not reach the peripheral zone and it was minimal in areas rich in fibromuscular tissue, such as the bladder neck. At times, nodular benign prostatic hyperplasia was unaf fected. A 4-quadrant treatment in the same plane often yielded small n onconfluent lesions. Confluent lesions in the same plane yielded appro ximately 30% greater depth of coagulation necrosis, which was achieved when 3 or 4 lesions were created on each side of the prostate (per si ngle transverse plane). Likewise, coagulation necrosis observed with 1 5 watts for 180 seconds was approximately 40% greater than that noted with the 50 watts for 60 seconds regimen. Our findings suggest that no ncontact laser prostatectomy is a safe procedure that can be improved by modifying the laser regimen and the spatial distribution of lesions .