Similarly to RARC and RARP, robotic-assisted partial nephrectomy (RAPN) has seen a strong rise in popularity with surgeons across Europe and North America. However, to date, no RCTs on the comparison to open partial nephrectomy (OPN) have been conducted successfully. While many retrospective studies have shown equivalence or even superiority of RAPN over OPN, these carry with them unavoidable biases.5 Unfortunately, conducting surgical RCTs comes with unavoidable hindrances, and oftentimes patients will already have been influenced to prefer one treatment option.
The described factors highlight the importance of feasibility trials in surgical domains. As such, we designed a pilot trial assessing the feasibility of randomization between RAPN and OPN which was based on a previous propensity score-matched study.6 The trial (ROBOCOP II) was conducted at the University Medical Centre Mannheim, which is part of the University of Heidelberg. The department represents a high-volume tertiary care center with extensive experience with kidney surgery and robotic-assisted surgery. Surgeons were only eligible for participation if they had performed at least 100 partial nephrectomies and 100 robotic procedures as primary surgeons without major adverse events.
Patients scheduled for partial nephrectomy due to localized renal neoplasms by their primary care physicians or urologists were assessed for eligibility if they were 18 and older and both RAPN and OPN were deemed feasible from preoperative imaging. Patients were excluded if they had a solitary kidney, were not able to give consent, or had multiple tumors.
Patients were then randomized via a web-based system in a 1:1 ratio and scheduled for surgery about one week after randomization. Treatment group allocation was not concealed.
The primary outcome was the feasibility of randomization which was defined as a randomization of more than 33% of eligible patients. Secondary outcomes included complications, operating time, intraoperative blood loss, warm ischemia time, and other factors.
Overall, of 218 patients assessed for eligibility, 78 were deemed eligible and approached for recruitment. The main reasons for ineligibility were that patients were not suitable for both surgeries (previous extensive operations, very large tumor with primary indication for radical nephrectomy, etc., n= 75) and that the patient required either no surgery, had metastasized disease or only BOSNIAK II cysts (n = 42). Of the approached patients, 52/78 (66%) were able to be recruited and randomized, thus surpassing the prespecified minimum rate of 33%. Of the 52 patients randomized, 50 were operated on within the trial. One participant declined participation, and one patient was reassessed in a multidisciplinary tumor board and underwent a radical nephrectomy.
In our exploratory analysis of the secondary outcomes, we were able to show statistically significant differences in both intraoperative outcomes and postoperative outcomes between the two study arms. For OPN there was both a shorter overall operating time of 18 minutes (OPN: 112 min, RAPN: 130 min, P = 0.046) and shorter warm ischemia times of 6.7 minutes (OPN: 8.7 min, RAPN: 15,4 min, P = 0.001). For RAPN, there was on average 212 ml less blood loss (OPN: 149 ml, RAPN: 361 ml, P < 0.001). Postoperatively, significantly fewer patients that had undergone RAPN needed opioids (OPN: 46%, RAPN: 16%, P = 0.024) and there were significantly fewer minor complications (Clavien-Dindo <3) in the RAPN group (OPN: 11; RAPN: 0, P < 0.001), while there were no differences in severe complications (Clavien-Dindo ≥3). This difference in complications was also reflected when assessing the complications with the use of the Comprehensive Complication Index (CCI) where the mean score was significantly higher for OPN, indicating a greater burden of complications (OPN: 14.0; RAPN: 4.9; P = 0.008).
This RCT represents the first trial to compare OPN and RAPN in a randomized fashion. Fortunately, it showed that randomization in this setting is feasible. This should encourage investigators to attempt more surgical RCTs in order to provide evidence-based recommendations.
In conclusion, this trial currently represents the highest level of evidence available for the comparison between OPN and RAPN. However, the trial does not answer questions on the non-inferiority of oncologic outcomes between the two approaches. These and quality of life outcomes are currently being gathered and expected soon.
Written by: Caelán Max Haney,1 Manuel Neuberger,2 Maurice Stephan Michel,2 & Karl-Friedrich Kowalewski2
- Department of Urology, University of Leipzig, Leipzig, Germany
- Department of Urology and Urological Surgery, University Medical Centre Mannheim, University of Heidelberg, Mannheim, Germany
References:
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- Cacciamani GE, Medina LG, Gill T, et al. Impact of Surgical Factors on Robotic Partial Nephrectomy Outcomes: Comprehensive Systematic Review and Meta-Analysis. J Urol. 2018;200(2):258-274.
- Kowalewski KF, Muller D, Kirchner M, et al. Robotic-Assisted Versus Conventional Open Partial Nephrectomy (Robocop): A Propensity Score-Matched Analysis of 249 Patients. Urol Int. 2021;105(5-6):490-498.