Transurethral GreenLight Laser Enucleation of the Prostate—A Feasibility Study

Introduction

T ransurethral electroresection of the prostate (TURP) and open prostatectomy are still the reference methods for the surgical treatment of patients with benign prostatic hyperplasia (BPH). Long-term effectiveness and relevant morbidity are characteristic of these procedures. In an attempt to reduce morbidity, several laser techniques for transurethral treatment of BPH were established recently. One of the most common is the HPS-GreenLight™ laser vaporization. The energy is delivered to the tissue via a side-fire laser fiber with a wavelength of 532 nm and a power of 120W. The short-term functional results after transurethral laser vaporization, measured by improvement in peak urinary flow rate (Q_max), reduction of postvoid residual (PVR) and International Prostate Symptom Score (IPSS) are comparable to those of TURP, while the perioperative morbidity is significantly reduced. ^{1 –3} The learning curve of the procedure is considered relatively flat. ⁴

Small to midsized prostates are treated with promising results and comparable efficacy to that of TURP. ⁵ Particularly in large prostate adenomas a disadvantage of the method is its limited volume reduction, which may be insufficient to maintain long-lasting good functional results. Therefore, high reintervention rates were reported in this subgroup. ²

An established procedure for the transurethral treatment of large prostates is holmium laser enucleation of the prostate (HoLEP), one of the first proposed laser techniques. It is known for good long-term results and sufficient volume reduction independent of prostate size. ⁶ Functional results compare favorably with those of TURP. The procedure is technically demanding, which may be one reason for the relatively slow spreading of HoLEP, despite good clinical results. ⁷

The purpose of this study was to prospectively investigate the feasibility of GreenLight laser enucleation of the prostate.

Patients and Methods

From December 2009 to June 2010, 21 consecutive patients underwent GreenLight laser enucleation for symptomatic BPH. Inclusion criteria were lower urinary tract symptoms from benign prostatic enlargement, transrectal ultrasonography (TRUS) prostate volume ≥50 cc, IPSS ≥15, and medical therapy failure. Exclusion criteria were neurogenic bladder disorders, prostate or bladder malignancies, and urethral strictures. All patients signed an informed consent. If indicated, prostate cancer was excluded by preoperative biopsy. Patient data are summarized in Table 1.

Preoperative prostate volume was determined by TRUS in two planes. Transurethral enucleation was performed with a 120W, 532 nm HPS GreenLight laser in combination with a 600 μ side-fire laser fiber. A 26F Olympus OES Pro resectoscope was used. Enucleated tissue was removed using a Piranha Morcellator (Wolf, Knittlingen, Germany); 0.9% saline was used for irrigation. All patients received intraoperative suprapubic drainage.

The surgical procedure is similar to the HoLEP technique described by Gilling. ⁸ Instead of the typical holmium laser incisions, the GreenLight laser vaporizes wide channels into the adenoma. First, the median lobe is enucleated by vaporization of deep channels at the 5 and 7 o'clock positions from the bladder neck to the verumontanum down to the surgical capsule of the prostate. The channels are connected just proximal to the verumontanum. The tissue is lifted up with the beak of the resectoscope and dissected toward the bladder neck. After the median lobe is removed, a channel at the 12 o'clock position is created from the bladder neck to the level of the verumontanum. The tissue lateral to the verumontanum is vaporized down to the surgical capsule.

Starting in this region, the lateral lobes are separated from the capsular floor until the bladder neck is reached. When the lateral lobes are separated up to the 9 and 3 o'clock positions, respectively, the enucleation progresses from the 12 o'clock channel downward to both sides, completely dissecting the lateral lobes. Ideally, the enucleation was performed bluntly with the tip of the resectoscope. The laser was used to dissect adherent tissue fibers put under tension with the resectoscope. The tissue was then removed with the morcellator. A single surgeon performed all procedures.

The operative time was defined as the interval between insertion of the resectoscope to placing the irrigation catheter. The weight of the removed tissue was noted, and applied laser energy was recorded. Complications during hospitalization were documented.

For postoperative follow-up, PVR and IPSS were recorded. The PVR was measured at the day of discharge or shortly after during an outpatient contact. The IPSS questionnaire was sent to the patients 2 to 9 months postoperatively. Postoperative Q_max and TRUS were not end points in this feasibility study. No patient was lost to follow-up.

The results are presented as mean±standard deviation. For statistical comparison of IPSS and PVR urine volume preoperatively and postoperatively, the t-test was used. Statistical significance was set at a value of P<0.05. Statistical analysis was performed using Excel Version 12.2.7, from Microsoft.

Results

Patient data are displayed in Table 1. Operative time was 112±27 minutes. One small perforation of the prostate capsule and three breakages of laser fibers were recorded as intraoperative complications. All broken fibers had to be replaced during the operation. Therefore, 1.1 fibers were used per patient. Relevant bleeding or hyperhydration did not occur. Catheter time was 1.2±0.4 days. The length of hospitalization was 3.6±0.9 days. All patients stayed in the hospital for one day after catheter removal to avoid the occurrence of complications after discharging. There was no clot retention or acute urinary retention during the postoperative course. None of the patients was bothered by urge incontinence.

Postoperatively, one patient had transient stress incontinence. Complete continence was regained within 6 weeks. All patients were able to void properly. During follow-up, none of the patients needed further interventions or hospital treatment.

The preoperative prostate volume was 75±38 cc; 35±22 g of tissue (47%) were removed with the morcellator. In addition, an average of 233,000J±93,000J were used for tissue vaporization.

Follow-up was 5.8±1.8 months. IPSS improved from 25±6 preoperatively to 5±9 (P=0.0001) and the PVR was reduced from 126±80 mL preoperatively to 11±18 mL (P=0.002).

Discussion

Transurethral adenoma enucleation with the GreenLight Laser can be performed in the same way as HoLEP. The different direction of light emission (holmium: 0-degree bare fiber; GreenLight: 70-degree side-fire fiber) does not necessitate significant changes. While tissue contact is not a problem with the holmium bare fiber, it should be reduced to a minimum with the GreenLight fiber to prevent destruction of the fiber.

The weight of the morcellated tissue is similar to the results to be obtained from HoLEP or TURP: Elzayat and Elhilali ⁹ obtained, with a preoperative average prostate volume of 59.3 cc, an average weight of removed tissue of 30 g. Shah and colleagues ¹⁰ recorded a ratio of 54.6 cc to 29.8 g. Gilling ⁶ observed a ratio of 58.5 cc to 27.2 g. For TURP, Ho and associates ¹¹ noted a ratio of 54.8 cc to 30.6 g. In our patients, the ratio is 74.6 cc to 34.7 g. Comparison of these data shows no significant differences. In addition to the enucleation, vaporization with a mean energy of 233 kJ was performed in our collective. This leads to a further reduction of tissue. A long-lasting volume reduction can be assumed for GreenLight enucleation.

Our operative time was significantly longer than that for HoLEP in established centers. It should be considered, however, that the results of the first 21 patients treated at our institution are presented. Comparing our results with the learning curves for HoLEP in other centers, we obtain similar results. For the first 25 cases of HoLEP, Placer and coworkers ⁷ noted an average operative time of 158 minutes at an average prostate size of 66.5 cc. After the first 100 patientsm the intervention time decreased to 84 minutes. ⁷ Du and associates ¹² reported an average operative time of 83 minutes with a prostate volume of 45 cc in the treatment of the first 50 patients. During the first 70 operations, Seki and colleagues ¹³ reported a mean operative time of 110 minutes with a prostate volume of 54 cc.

Our experience shows that the adaptation of the HoLEP technique for GreenLight Laser is directly possible. Serious complications during the learning curve did not occur. The enucleation and morcellation of the adenomatous tissue were feasible in all patients. All procedures were completed. After the procedure, all patients were able to void properly without relevant PVR. No recatheterization or reintervention was necessary during the follow-up. Permanent stress incontinence, relevant blood loss, or capsule perforation was not observed. During the learning curve for HoLEP, a recatheterization incidence of 8% is reported. Transient urinary incontinence and permanent urinary incontinence are, with 60% and 12%, respectively, very common during the first HoLEP interventions. ⁷

The GreenLight laser enucleation allows switching from resection to vaporization at any time during the intervention. This feature gives additional safety and avoids high incidence of stress incontinence when performing the first cases. If apical tissue remains after enucleation, it can easily and safely be vaporized at the end of the procedure.

Conclusion

To assess the significance of the GreenLight Laser enucleation, further evaluation is required.