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- Materials and Methods
- Conflict of Interest
The increase in the use of new and different imaging methods over recent decades has led to an increase in incidental finding of solitary renal masses . Small renal masses (SRMs; <4 cm) represent 48–66% of cases . With more than half of SRMs being surgically removed, surgical excision remains the most definitive therapy for such solitary lesions. Radical nephrectomy was previously considered the ‘gold-standard’ treatment for SRMs of <4 cm. However, nephron-sparing robotic-assisted partial nephrectomy (RPN) has been gaining popularity in treating peripherally placed renal tumours, particularly in patients where preservation of renal function is important [3, 4]. Thus minimally invasive PN is increasingly replacing open radical nephrectomy and PN because of its equivalent efficacy and the advantages it potentially offers; namely lower intraoperative blood loss, a reduced length of stay (LOS) and acceptable warm ischaemia time (WIT) . The evolution from open radical nephrectomy through open PN and now LPN and RPN is mostly due the advantages of robotic over laparoscopic surgery, which has been evaluated in different fields of surgery [5, 6]. In addition, RPN has the added advantage of aiding the learning curve for management of complex renal tumours [7, 8].
With a rise in incidental renal cell tumours and the ever expanding indications for robotic surgery in urology, in particular PN, an evaluation of laparoscopic and robotic approaches is required. This is warranted as most of the evidence for robotic surgery is generated from small single centre experiences or retrospective studies. In the present study we aimed to compare the RPN and LPN approaches for the treatment of SRMs. We evaluated intraoperative and postoperative variables to compare the two methods.
- Top of page
- Materials and Methods
- Conflict of Interest
In the present study we aimed to evaluate the role of RPN in treating SRMs (mean size of <4 cm) and to objectively compare RPN with LPN. The results of this meta-analysis of 256 patients showed that were no significant differences in operative variables. This is despite the fact that the individual studies report a better operative profile for RPN; namely a shorter total OPT, WIT and reduced intraoperative EBL. Because these operative factors strongly affect the likelihood of curative resection, preservation of nephrons and ultimately survival, these findings are important. Of note is also the level of laparoscopic/robotic experience of the primary surgeons which ultimately affects the OPT .
Similar findings have been reported by other comparative studies [16, 50, 51]. Benway et al. in a multi-institutional analysis of perioperative outcomes reported better operative and similar early oncological outcomes. Despite its retrospective nature, it highlights the important role of RPN in the treatment of SRMs, where it appears to be less affected by tumour complexity [7, 17, 51]. In a recent study, Lee et al. , concluded the beneficial role of RPN in treating more complex and posteriorly located tumours.
One limitation to note is a lack of standardised scoring for tumour complexity. Only two of the studies included reported on a nephrometry score [30, 49]. The location of the tumour can add to the complexity of the operation and affect perioperative variables . A higher nephrometry score is associated with increased EBL, WIT and LOS as was assessed by Hayn et al.  in a group of patients undergoing LPN. Standardising the description of anatomical features of renal tumours has resulted in development of multiple scoring systems .
The robotic approach has many potential advantages over the laparoscopic as the da Vinci robot provides a three-dimensional view of the surgical field with increased degrees of freedom. The robot can eliminate tremor and provides scaling of motions. Despite this, there are disadvantages associated with robotic approach. Maintaining the robot is costly with the capital expenditure being well over 1 million Euros and the annual maintenance/running costs of 100 000 Euros . In a recent single centre analysis of short-term outcomes, Elsamra et al.  did not find any significant difference between RPN and LPN. However, RPN was associated with an increased cost. In addition to this, setting up the system is time consuming and is thought to increase the OPT. However, having said that, RPN has been suggested as an alternative to traditional LPN to improve the learning curve for trainee surgeons.
The bulk of evidence in support of RPN is gathered from a few either initial-experience, retrospective, or non-randomised studies (Table 4) [58, 59]. These reports are suggestive of RPN becoming a viable alternative to open PN and LPN in carefully selected patients [16, 60], with the advantages of the robotic system being weighed against its cost [60, 61]. In a multi-institutional study, RPN was shown to be safe and feasible for selected patients with renal hilar tumours . Interestingly, most of the reports on RPN are illustrative of a hybrid method. Whereby the initial part of the surgery is performed laparoscopically and then robotic surgery is performed . However, this depends on the surgeon's preference and laparoscopic experience.
One of the limitations of the present meta-analysis that must be considered is the lack of randomised control trials on the current topic. All of the studies analysed are comparative studies with no random sequencing or concealment. Most of the studies were retrospective with only one study prospective  in nature. Only one study  mentions its exclusion criteria. In addition, some of the studies had poorly defined outcome measures. Almost all of the studies lacked medium- to long-term follow-up and data on tumour margins, all of which are important when considering early and long-term success of either treatment groups. Neither the allocation nor the assessment of outcome was ‘blinded’. In addition, publication bias based on current studies, as well as variation in inclusion criteria, treatment protocols, varying operative techniques and outcome assessment between studies should be taken into account.
Additionally, the risk of positive margins may be greater in LPN and RPN than with the open technique. Thus to avoid this there is tendency to resect more normal renal parenchyma compared with open PN. This can have great impact on the long-term function of the remaining renal tissue and long-term oncological data.
The learning curve for laparoscopic surgery appears longer than robotic surgery [30, 62] and can affect outcomes . Such variability in the level of experience and expertise of surgeons and their learning curve associated with the technique and its effect on postoperative outcomes could not be accounted in the present study. Only one study reported the learning curve for transition from laparoscopic to robotic surgery . Although it focuses on the experience of one surgeon, it highlights the technical challenges associated with the laparoscopic technique and the quick learning curve in transition from LPN to RPN. Mottrie et al.  analysed the impact of learning curve on perioperative outcomes of patients with parenchymal renal tumours who underwent RPN. Interestingly, they found a short learning curve for WIT (<20 min) and console time (<100 min) but not for EBL or overall complications. However, Pierorazio et al.  found no difference in perioperative outcomes of RPN when comparing the early and late phase of experience. Improvement were noted in the OPT, WIT and EBL for the LPN group as their level of experience increased.
Further evaluation of surgical techniques is required, as there is variability between different centres and the particular techniques used. For example novel approaches such as zero ischaemia [65, 66] techniques can have great impact on patients, particularly where renal function is of concern.
Finally, we conducted a further Bland–Altman analysis of some of the operative variables (Table 6) to compare their reproducibility and mean difference in techniques. Comparing OPT, WIT and EBL for each group revealed poor correlation either with an absolute or proportional difference (Figs 7-9). These differences may be reflective of the variability in the actual techniques and the level of experience of surgeons in either laparoscopic or robotic surgery. However, the safety and feasibility of RPN as an alternative to LPN has been shown in other similar studies .
In conclusion, the present study highlights the lack of extensive evidence for using robotic surgery over laparoscopic for treating small renal tumours in selected patients. Although not significant, the results from different studies showed a trend towards use of the robotic technique in treating small and complex renal tumours. To more objectively evaluate the relation between RPN and LPN, there is a need for randomised control trials. More long-term data on surveillance and tumour recurrence is required to fully elucidate role of robotics in PN.