The SP surgical system represents a second-generation single-port robotic system that contains a multichannel port, which accommodates an articulating high-definition robotic camera with three 6-mm double-jointed articulating robotic instruments. These instruments allow for intracorporeal triangulation while reducing the instruments’ clashing. Since its release on the market, all the major urological procedures have been performed, but the procedure that gained the widest popularity and generated more prosperous literature has undoubtedly been robot-assisted SP radical prostatectomy (SP-RARP). SP-RARP has been first reported by Dr. Jihad Kaouk, who has been followed by other affirmed colleagues across the United States of America and more.
Notwithstanding the fascinating performances allowed by the novel platform driven by an experienced robotic surgeon, controversies exist about the translation of its adoption into benefits in perioperative outcomes after a standardized procedure as RARP.
In this scenario, the first quantitative synthesis of available literature data from studies comparing SP-RARP versus MP-RARP has been performed by the European Association of Urology Robotic Urology Section (ERUS) Working Group on Science and published on Urology, The Gold Journal, aimed to look for eventual advantages in terms of perioperative outcomes relative to the adoption of the SP surgical system.
Four comparative studies of interest were retrieved, including a total of 610 patients pooled for meta-analysis of data. The patients of the studied treatment groups (SP-RARP versus MP-RARP) had comparable preoperative characteristics. No significant differences were found when comparing SP-RARP versus MP-RARP in terms of operative time, blood losses, complications rate, and positive surgical margins. Conversely, SP-RARP was found to allow for a shorter hospital stay (weighted mean difference -0.79 days, 95% confidence interval -1.07; - 0.52, p < 0.001) (Figure 1).
Figure 1 – Forest Plots depicting the quantitative pooled analysis of studies comparing SP-RARP (experimental) versus MP-RARP (control). A) Operative time (min); B) Blood loss (ml); C) Clavien-Dindo > grade II complications; D) Hospital stay (days); E) Positive Surgical Margins’ rate. CI = confidence interval; IV = interval variable; SD = standard deviation.
In summary, the data available for analysis showed that perioperative outcomes typically evaluated after RARP are comparable since the beginning of the learning curve of SP-RARP, even when SP-RARP challenges MP-RARP performed at tertiary care institutions.
On the other hand, the findings of our review remark that the “SP philosophy” could be the winner at the pain outcomes analysis. As such, SP-RARP was found to allow for shorter hospital stays and more likely to be an “outpatient procedure”. Indeed, the likelihood of a patient’s discharge within 24 hours after surgery was higher after SP-RARP.
But results have to be interpreted with caution. We acknowledge the intrinsic limitations of the available retrospective comparisons between SP-RARP and MP-RARP. As such, transperitoneal and extraperitoneal SP-RARP cases are usually pooled together. Shorter hospitalization and decreased need for postoperative narcotics have typically favoured the extraperitoneal approach during SP-RARP. Thus, a synergistic effect could occur when analysing the pain outcomes of SP-RARP, as a sum of the extraperitoneal surgical approach and the adoption of the SP platform itself. Moreover, a further hidden bias related to a faster patient’s discharge when SP-RARP is performed could exist. That is to say that the surgeon could feel compelled to discharge the patient earlier when the novel technology is adopted.
More studies comparing single-port versus “multi-ports” robotic surgery are needed. Such studies should be based on larger, prospectively collected, sample sizes and longer follow-ups.
There are crucial steps of radical prostatectomy that still represent an issue when performed by using the SP platform: most of the urologists who are already delivering satisfactory results when performing MP-RARP could have troubles in replicating their performances when performing SP-RARP. If this is the case, it would not be a fascinating transition. Up to date, there are no specific data about transition from MP-RARP to SP-RARP for neither expert nor novice robotic surgeons.
One of the major issues with our analysis is related to the generalizability of the findings outside of tertiary care centers. Specifically, the SP experiences reported in the pooled studies come from high-volume institutions and are by highly trained surgeons, with extensive experience both in standard multi-arms and SP robotic surgery. As such, the substantial equivalence between the two approaches may have been affected by the previous experience.
Moreover, besides the differences in the perioperative outcomes investigated within the setting of the present quantitative synthesis, there are other important issues to be considered when assessing the “quality” of RARP that we were not able to pool based on the available published series: namely, catheterization time, continence, and potency outcomes were not assessed.
The urology community still needs to define the optimal indications for a cost-effective adoption of the novel SP surgical platform. It is hypothesized that the “popular” multi-arms robotic systems will probably remain the standard for transperitoneal, “conventional” prostatectomy. This is yet to be investigated by future clinical trials.
On the other hand, the advent of the SP platform has prompted the re-discovery of different access routes to the pelvic fossa. Ideally, all of them are feasible, while pursuing a minimally-invasive robotic approach at the same time.
In selected cases, the potential for avoiding the abdominal cavity could decrease surgical morbidity and minimize surgical dissection.
The results from the present pooled analysis have to be taken with caution. Indeed, according to the basic principle of analysis, whenever an effect is significant, all values in the confidence interval should be on the same side of zero (either all positive or all negative), whilst the analysed operative time, blood loss, and hospital stay failed in this criterion.
Instead of concluding that no significant differences were found between SP-RARP and MP-RARP, we conclude by the moment that the available data are inconclusive for these parameters. Looking at non-significant effects in terms of confidence intervals makes clear why the null hypothesis of no differences between the approaches should not be accepted when it is not rejected.
Further studies, possibly randomised, with long-term oncological and functional outcomes are warranted to critically evaluate the impact of the adoption of the SP platform on the outcomes of robotic prostatectomy.
Written by: Riccardo Bertolo, Urology Department, San Carlo di Nancy Hospital, Rome, Italy.
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