Laparoscopic partial nephrectomy has been widely used in renal cell carcinoma treatment. The efficacy of GreenLight laser on Laparoscopic partial nephrectomy is still unknown.

To present the first series of laparoscopic partial nephrectomy (LPN) by GreenLight laser enucleation without renal artery clamping. Due to the excellent coagulation and hemostatic properties of the laser, laser-assisted LPN (LLPN) makes it possible to perform a “zero ischemia” resection.

Fifteen patients with T1a exogenous renal tumors who received high-power GreenLight laser non-ischemic LPN in our hospital were retrospectively analyzed. All clinical information, surgical and post-operative data, complications, pathological and functional outcomes were analyzed.

Surgery was successfully completed in all patients, and no open or radical nephrectomy was performed. The renal artery was not clamped, leading to no ischemic time. No blood transfusions were required, the average hemoglobin level ranged from 96.0 to 132.0 g/L and no postoperative complications occurred. The mean operation time was 104.3 ± 8.2 min. The postoperative removal of negative pressure drainage time ranged from 5.0 to 7.0 d, and the mean postoperative hospital stay was 6.5 ± 0.7 d. No serious complications occurred. Postoperative pathological results showed clear cell carcinoma in 12 patients, papillary renal cell carcinoma in 2 patients, and hamartoma in 1 patient. The mean creatinine level was 75.0 ± 0.8 μmol/L (range 61.0-90.4 μmol/L) at 1 mo after surgery, and there were no statistically significant differences compared with pre-operation (P > 0.05). The glomerular filtration rate ranged from 45.1 to 60.8 mL/min, with an average of 54.0 ± 5.0 mL/min, and these levels were not significantly different from those before surgery (P > 0.05).

GreenLight laser has extraordinary cutting and sealing advantages when used for small renal tumors (exogenous tumors of stage T1a) during LPN. However, use of this technique can lead to the generation of excessive smoke.

Kidney cancer is a common tumor, accounting for 2%-3% of all carcinomas, and is one of the top 10 cancers worldwide[1]. Recent years have witnessed a consistent increase in the incidence rate in most countries[2]. To date, surgical therapy is still the primary treatment, especially in patients with a small renal mass (SRM), although surveillance is under study. Recent guidelines indicate that, as far as possible, all patients with tumors < 7 cm should receive nephron-sparing surgery (NSS). The disease-specific prognosis is similar between radical nephrectomy and partial nephrectomy (PN), with the benefit of better protection of kidney function in PN patients[3]. Thus, a critical target of NSS is to preserve the maximum amount of kidney parenchyma, with minimum warm ischemia time (WIT). Hilar clamping has been standard practice in previous decades to achieve the lowest blood loss. However, blockage of the renal blood supply results in WIT, and even renal function damage[4]. Bleeding is still the most frequent complication of NSS, with a risk of transfusion in up to 5% of patients[5]. Optimization of Renal cell carcinoma surgical treatment has received increased research interest. Over the years, progress has been made in reducing the risk of bleeding and the complications of WIT. From open to laparoscopic partial nephrectomy (LPN), therapy has recently changed to robot auxiliary partial nephrectomy[6]. Patients receiving laparoscopic surgery had lower intraoperative blood loss than those receiving the open surgery, and postoperative complications did not increase[7]. However, LPN prolonged WIT as the procedure is challenging even for experienced surgeons with critical time scales[8]. Thus, various techniques to reduce or eliminate WIT surgery have been used, including specific kidney artery block, targeted kidney blood flow or renal parenchyma clamping, laser-assisted minimal invasive partial nephrectomy (MIPN), MIPN auxiliary radio frequency, MIPN auxiliary water jet, and sequential preset kidney suture[9]. Although these techniques are not widely accepted, their applications are being increasingly investigated.

The initial GreenLight laser used potassium titanoxate phosphate, which produced a green visible light beam at 532 nm with a short penetration depth of 0.8 mm. GreenLight is selectively absorbed by hemoglobin rather than water within the tissue. The laser works by photoselective vaporization of tissues. This was followed by the development of a high-power 120W (GreenLight HPS) laser and, finally, the development of an 180W GreenLight accelerated performance system (XPS) laser with a Moxy fiber. The power of the laser and the laser beam area is increased by 50%, and the energy density at the laser point is similar, thus maintaining similar safety to the previous 120W system[10]. However, the GreenLight laser was widely used in transurethral resection of the prostate (TURP) for lower urinary tract symptoms associated with benign prostate enlargement, which led to the introduction of less invasive treatments. Although there have been animal experiments and pre-clinical investigations on GreenLight laser for NSS[11,12], the safety and feasibility of this technique in human NSS is unclear.

As different types of lasers have been tested, the purpose of this study was to demonstrate the feasibility of GreenLight (high-power 80-100W) laser-assisted LPN (LLPN). When oncology results and actual care standards match, tumor excision ability and the pathological report after laser excision are important.

It is standard procedure to perform laparoscopic surgery for the removal of renal tumors and SRMs, with renal artery clamping and WIT. However, the difficulty and requirements of LPN lead to longer WIT, compared with the open method. Moreover, WIT deserves more attention in the case of pre-damaged organs or a single kidney[8]. More recently, robot-assisted LPN has emerged as an alternative to LPN. Compared with laparoscopic surgery, the ischemia time during robotic surgery is significantly shortened, thereby reducing the risk of renal dysfunction[14]. Current studies have shown that renal artery clamping for more than 30 min can cause irreversible renal function damage[15]. Recently, Thompson et al[16] proposed that as long as the blood supply to the kidney is blocked, kidney damage will gradually increase every minute. These findings present a significant challenge to urologists in how best to preserve renal function in patients with early renal tumors. Therefore, a complete unblocked nephrectomy of the renal artery is necessary. This technique was first reported by Marshall et al[17] and Abaza et al[18] in 2000. Surgeons performed PN without blood vessel clamping in patients with SRMs using hemostasis devices such as double-click electro-coagulation[18]. It seems that decreasing WIT could be a favorable modifiable risk factor to avoid postoperative kidney dysfunction. Thus, we attempted to investigate the safety and feasibility of the GreenLight laser, and to reduce or prevent WIT in renal laparoscopic surgery.

The application of a laser during kidney surgery remains uncertain in the experimental or preclinical stage, although it has been widely used and extensively investigated in other medical areas. As the laser's efficacy depends on the wavelength and the proportion of water in the tissue, its efficacy must be determined. The feasibility of using lasers in kidney procedures has been shown previously[19-21]. Kyriazis et al[19] first reported 2 cases of unblocked thulium laser-assisted robotic PN with no obvious intraoperative or postoperative complications, and the pathological results showed a negative surgical margin. Boris et al[22] successfully carried out green laser partial zero ischemia nephrectomy in pigs, and the results showed that the green laser effectively stop bleeding within a very short time, with a tissue penetration rate of only 0.8 mm. The GreenLight laser applied in the present study at 532 nm, was preferentially absorbed by oxyhemoglobin (absorption coefficient 102/cm), but not by rinsing (absorption coefficient 104/cm). The increased energy absorbed from hemoglobin caused the tissue to vaporize, leading to physical separation of the tissue. In addition, it resulted in thermally-induced coagulation of superficial blood vessels; thus, an almost blood-free area was produced for surgery. The 532 nm wavelength has a small penetration depth (1-2 mm) leading to less charring[15,23,24]. Thus, GreenLight laser vaporization is considered an effective alternative for TURP. Based on this, we attempted to demonstrate the balance between laser energy and NSS.

In this study involving 15 patients, no obvious complications such as urine leakage and bleeding occurred during the perioperative period. The postoperative follow-up examination indicated that no patient had positive surgical margins or postoperative local recurrence, and there were no significant statistical differences between preoperative and postoperative serum creatinine levels. LPN is safe, feasible, and beneficial for maximum preservation of renal function in patients. To our knowledge, this is the first report on GreenLight LLPN to date. Moreover, all the tumors were removed without WIT, which protected kidney function. However, one of the major limitations of surgery was the excessive accumulation of smoke during vaporization of tissue. We attempted to reduce this by rinsing, but visibility was not improved. Favorable visibility could be obtained by using one of the trocars as a fume hood. However, this was not the best option as better visibility could not be acquired from suction alone. In addition, it appears that undefined resection margins and positive resection margins are an issue on histopathological examination. Nevertheless, this should be validated in further large-cohort studies. All patients with unclear or positive surgical margins were followed up and no tumor recurrence has been observed.

The potential efficacy of laser-assisted LPN without WIT has been witnessed for over a decade[25], but until now this technical option has been considered experimental. In this retrospective study, which consisted of the first series of patients to date, we showed the strengths and main problems of GreenLight (80-100W) LLPN. However, this technique is mainly limited to single cases with a small tumor volume and superficial locations. The number of cases in the present study was small; thus, further clinical trials are required to determine whether this technique should be promoted.