Today PN is an accepted procedure for small renal malignant tumors, but there are many options for performing this procedure according to preference of the surgeon, situation of the patient, and availability of surgical equipment, ablative procedures, open, laparoscopic, and robotic surgery may be selected. At the present time for managing renal tumors it is emphasizes to conduct a nephron sparing technique due to similar oncogenic results while potentially reducing renal and cardiovascular morbidity in comparison to RN (4). While open RN has been the gold standard procedure for renal tumor operation, PN is currently utilized for renal tumor surgery in both high and low volume urological centers worldwide. Many previous studies has revealed better overall survival in patients who undergo PN compared to RN, and has shown at least similar oncological outcomes (5).
Although at the present time PN is the gold standard treatment for localized and small renal tumors, however, there is no consent over the effects of duration and type of intraoperative ischemia on renal function after PN (6). For evaluating the renal function after PN or RN, serum Cr is measured, although this test is not a reliable indicator of renal function, it is currently the most commonly used, and the easiest test for assessing renal function after partial nephrectomy. The pathogenesis of acute ischemia on renal function that causes acute kidney damage is based on vascular events, obstructive events, and reperfusion injuries. During these three inevitable processes persistent vasoconstriction and abnormal response of endothelial cells, formation of casts by sloughed tubular epithelial cells in the kidney and membrane debris that obstruct tubules, and finally generation of reactive oxygen species, hyper coagulation states, cellular derangement, and micro vessel congestion and compression can significantly reduce renal blood flow. On the other hand, there are many preoperative factors that can have influence on postoperative renal function. Age, sex, tumor size, presence of solitary functional kidney, ischemia type, duration of ischemia, amount of preserved functional kidney, and kind of surgical intervention are among these effective factors. The optimum time of ischemia during PN has not been determined yet, but warm ischemia time (WIT) less than 30 minutes historically thought to allow complete recovery of kidney function. In spite of this data, in a human study in 40 patients who underwent open partial nephrectomy with WIT more than 30 minutes, a greater than expected resistance to ischemia time was shown (7). Overall, according to several studies, 20 to 25 minutes represents the most accurate cut- off to separate patients who do and do not develop short and long term renal function decline after PN (8-14).
In a clinical trial by Rezaeetalab and coworkers for comparing laparoscopic (LPN) versus open partial nephrectomy (OPN), for small renal tumors, they have shown that LPN has some benefits over OPN, including decreasing post-operative pain and higher patient satisfaction, but have suggested higher possibility of positive tumor margin and urinary leakage in LPN (15). This study correlates with our study in the point of no complication.
In a meta-analysis by Leow JJ and coworkers for comparing outcomes of robotic partial nephrectomy (RPN) versus LPN, demonstrated that RPL confers a superior morbidity profile compared to LPN in most of the studies (16). We didn’t have any significant morbidity in our study.
In 2 consecutive systematic reviews and meta-analyses by Zhonghua Shen and coworkers and Xia L. and coworkers for comparing perioperative outcomes of robot-assisted partial nephrectomy (RAPN) and OPN, demonstrated that RAPN offered a reduced perioperative complications, lesser blood loss, and shorter period of hospital admission than OPN, suggesting that RAPN may be an useful alternative to OPN(17, 18). We didn’t have availability to robotic surgery and regarding the cost of robotic surgery it may have a negative point in our center.
In another systematic review by Wang Y. and coworkers for evaluating the cost-effectiveness of management options for small renal mass surgeries, ablation was cost-effective versus nephron sparing surgery and LPN was cost-effective versus the open approach (19). In our study OPN is a significant cost-effective procedure with no need for expensive equipment.
Morelli L. and coworkers in a clinical trial using Robotic surgery and hemostatic agents in partial nephrectomy lead to higher rate of success (82%) without vascular clamping and suggested RAPN as a technique to overcome technical challenges of LPN (20). We didn’t have any technical challenge in our clinical trial.
Nowadays open PN is evolving as the standard of care for management of all amendable renal tumors with laparoscopic and robotic assisted surgery has being widely used(21). Regarding better preservation of renal function in OPN, in comparison to RN, this technique seems to have a major benefit. LPN seems to be associated with a longer ischemia time, a higher re-operative rate, and also increased complication rates. Currently, surgeons have main concerns over preservation of renal function in any operative techniques with continued efforts toward decreasing warm ischemia without compromising the oncological efficacy (21). In our study we have omitted any type of ischemia in setting of exposed renal artery, ready for clamping and this means lower risk of ischemia in preserved, functioning and healthy renal tissue.
Funahashi Y. and coworkers compared warm and cold ischemia on renal function after PN and reported that warm ischemia for more than 25 minutes caused widespread injuries to the operated kidney, whereas cold ischemia for less than 58 minutes prevented ischemic injury to the preserved part of the kidney (22). We didn’t use any type of ischemia, as a result, no ischemia induced complication could be considered.
In a study conducted by Jiwei Huang and coworkers found that in comparison to conventional LPN, by considering the safety and efficacy of laparoscopic radio frequency ablation (LRFA) during a prospective randomized controlled trial, LRFA assisted tumor enucleation with no ischemia, enables tumor excision with better renal function preservation (23). This clinical trial confirms the feasibility and safety of our study.
Partial nephrectomy is an accepted procedure for small renal malignant tumors both in high and low volume centers. There are many options for performing this procedure according to preference of the surgeon, situation of the patient, and availability of surgical equipment. In our technique of surgery, we have omitted any type of ischemia in setting of exposed renal artery and showed that this technique may be feasible and cost effective. We suggest more studies with higher number of patients to support the results of this study.