Interstitial Laser Ablation of the Prostate

Abstract

Interstitial laser therapy or coagulation (ILC) is a minimally invasive procedure for the treatment of benign prostatic hyperplasia (BPH). The objective of ILC is to achieve a marked volume reduction and, consecutively, decrease urethral obstruction and obstructive and irritative symptoms. To induce shrinking of the adenoma while preserving surrounding tissues, coagulation necrosis is generated well inside the adenoma. not at its urethral surface. The result is secondary atrophy and regression of the prostate lobes, not sloughing of necrotic tissue. This potentially avoids all problems related to tissue sloughing, such as irritative symptoms or an increased risk of urinary tract infections. In interstitial laser coagulation the applicator can be inserted as deeply and as often as necessary to coagulate any amount of tissue. Several experimental and clinical studies have been published, demonstrating the desired effects and excellent clinical results. For ILC, a Nd: YAG or diode laser is used in combination with specially designed fibers. In vitro experiments were initially done with constant power and later with stepwise reduced power and various radiation times in order to evaluate the maximal achievable lesion size without tissue carbonization in the shortest possible treatment time. The treatment volumes depended on the length of of the applicator and could be more than 7 ml. To achieve short radiation times but to avoid charring, stepwise reduced powers were favorable. These were repeatedly optimized and tested in vivo in the canine prostate. Lesion diameters of up to 20 mm were achieved. For increasing treatment safety, an optical feedback system was developed. For clinical use, interstitial applicators are inserted into the bulky tissue transurethrally through a cystoscope under direct vision. The number of fiber placements depends on the size and configuration of the gland. The most advanced radiation techniques which are currently used are based on temperature feedback controlled radiation cycles. Several studies indicated the effectiveness of interstitial laser coagulation of BPH regarding all of the three characteristics of the disease: symptoms, obstruction, and enlargement. All studies reported marked improvements in AUA score, peak flow rate, residual urine volume, and prostate volume. Pressure-flow studies demonstrated a sufficient decrease of the intravesical/detrusor pressure, urethral opening pressure. and the urethral resistance. Long-term results demonstrating sustained success for up to 3 years were reported in a series of 394 patients. Complications were rare. Prograde ejaculation was maintained in approximately 90% of the ILC patients. Urinary drainage, however, frequently was required in the postoperative period. ILC is suitable to debulk even large prostates and to treat highly obstructive patients. Therefore, ILC can be seen as a true alternative to transurethral resection of the prostate with certain advantages, such as almost no serious morbidity, and with certain disadvantages, such as the need for postoperative catheterization. ILC, however, can be done under local anesthesia and does not require hospitalization.