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Erbium:YAG Laser Incision of Urethral Strictures for Treatment of Urinary Incontinence after Prostate Cancer Surgery

Principal Investigator: FRIED, NATHANIEL M
Institution Receiving Award: JOHNS HOPKINS UNIVERSITY
Program: PCRP
Proposal Number: PC020586
Award Number: DAMD17-03-1-0087
Funding Mechanism: New Investigator Award
Partnering Awards:
Award Amount: $271,413.18


There are approximately 180,000 prostate surgeries in the United States each year for benign and malignant prostate cancer. Surgical incisions in the urethra and/or reconnection of the urethra to the bladder neck during prostate surgery can result in a narrowing, stenosis, or stricture of the urethra from scar formation during wound healing. Urethral and bladder neck strictures occur in 5'-20' of all prostate surgeries, causing problems with urination. Treatments for urethral stricture include inflation of a balloon to dilate or open up the urethra, or incision of the urethral wall to reduce pressure using several different cutting instruments including cold knife, electrocautery, and Holmium:YAG laser. These procedures have widely variable success rates ranging from 20'-80' (dependent on differences in surgical technique and skill, type of stricture, patient post-operative monitoring time, wound healing characteristics, and definition of stricture). The most common complication is stricture recurrence due to tissue damage caused during the treatment. Multiple balloon dilations or surgical incisions in complicated urethral strictures do not provide an increased benefit, leaving the patients without an effective method of treatment for their urinary incontinence.

The failure rate of conventional stricture treatments is presumably due to damage to the urethral wall in the form of mechanical damage (e.g., wall stress during balloon dilation) or thermal damage (e.g., heating of adjacent tissue during cutting with laser or electrocautery), resulting in restricturing during wound healing and problems with urination. Despite reasonable success rates, the Ho:YAG laser has been shown to produce significant thermal damage to adjacent healthy tissue during incision. The Er:YAG laser is much more precise than the Ho:YAG laser, reducing peripheral thermal damage by over an order of magnitude. We therefore hypothesize that the Er:YAG laser, which is capable of precisely incising the urethral stricture with minimal peripheral thermal damage to adjacent healthy tissue, will limit scarring and result in higher success rates.

We intend to modify and optimize the Er:YAG laser system and optical fiber delivery system for precise incision of urethral tissue. Studies will be conducted in a porcine animal model both ex vivo and in vivo to optimize the instrumentation. Then an improved technique for creating strictures will be developed to both better understand the mechanism of stricture formation and assist in our laser treatment of strictures. Finally, a comparative study will be conducted using the cold knife, Ho:YAG laser, and Er:YAG laser to determine whether the Er:YAG laser provides improved success rates in treating urethral strictures over conventional treatments.