Update of Laser Technology in Urology

Abstract

SUMMARY U rologists use lasers for both soft and hard tissue applications, including most commonly laser incision or vaporization of the prostate for treatment of benign prostatic hyperplasia and fragmentation of urinary stones during laser lithotripsy. Other applications include incision of urethral and ureteral strictures, treatment of bladder cancer, bloodless partial nephrectomy, treatment of penile carcinoma, tissue welding, and photodynamic therapy of bladder and prostate cancer. Overall, the future of lasers in urology looks bright. New laser systems continue to enter the urology clinic that are more powerful, more compact, more versatile, and less expensive than the previous lasers, providing the urologist with the means to develop new minimally invasive laser applications in urology and improve on existing applications. For example, the recent introduction of higher power solid state lasers, such as the 100 W Ho:YAG and 120 W KTP lasers, has resulted in more rapid and efficient incision or vaporization of prostate tissue during treatment of benign prostatic hyperplasia. On the horizon, even more compact and efficient laser technologies, such as fiber lasers, may replace current solid state lasers for use in BPH treatment, and photodynamic therapy may also represent a promising alternative to the photothermal laser ablation techniques currently used in the clinic for treatment of BPH. Applications of the high-power KTP laser will expand beyond BPH, to other procedures requiring excellent hemostatic properties during laser incision, such as laparoscopic partial nephrectomy. While several new lasers are being tested for lithotripsy, issues with cost (e.g., thulium fiber laser), the fiber delivery system (e.g., erbium laser), or lack of multiple-use applications (e.g., FREDDY laser) will need to be overcome before the holmium laser can be replaced. Development of more flexible hollow waveguides for the delivery of pulsed carbon dioxide and erbium laser energy through flexible endoscopes may allow these laser wavelengths to be used in the upper urinary tract for more efficient laser lithotripsy. The results for laser treatment of strictures have been disappointing, although more precise lasers for tissue incision with minimal thermal insult to healthy tissue (e.g., erbium laser) may provide better results. There remains a fundamental need to better understand the wound healing method before strictures can be eliminated. Laser tissue welding is ideal for urology, which has many applications needing rapid, microsurgical, fluid-tight tissue closure. However, the field has progressed slowly and faces competition from more validated, lower-cost, and easy-to use tissue closure techniques (e.g., sutures, staples, biological adhesives). Although numerous scientific laser tissue welding studies have been conducted, few of these studies have advanced to the stage of clinical testing. In the field of photodynamic therapy, photosensitizing drugs will continue to be developed with longer activation wavelengths for destruction of larger tissue volumes such as the prostate gland. These drugs will have shorter clearance times, they will be taken immediately prior to light activation, and they will not have the side effects usually associated with the early photosensitizing drugs, such as skin photosensitization. Technological advances in diagnostic imaging and robotics will allow these minimally invasive laser procedures in urology to be performed with even more precision and control, and with real-time monitoring, thus improving the efficacy and safety of the procedure.