Currently, international urological guidelines lack clear recommendations regarding the optimal surgical approach for robot-assisted partial nephrectomy (RAPN) in the surgical treatment of localized renal cell carcinoma (RCC) [1,2]. According to the decubitus of the patient, RAPN can be performed either in a standard flank position (Fig. 1) or in a supine position (Fig. 2) [3]. The standard flank position, besides being time-consuming, is associated with numerous anaesthesiologic drawbacks, especially involving respiratory function (e.g., decrease in pulmonary compliance, tidal volume and vital capacity with enhanced risk of hypoxemia) [4]. Moreover, peculiarly in obese patients, this decubitus may portend peripheral nerve and soft tissues injuries [5]. Conversely, the supine decubitus does not need for any additional time in repositioning the patient after anesthesia, reducing the risks of tubes' and vascular accesses’ dislocations. Moreover, it may lower the ventilation/perfusion mismatch usually associated with prolonged mechanical ventilation in lateral position [6]. Finally, it may significantly foster patient recovery, due to significantly lower postoperative pain and need for narcotics [3].

Nowadays, the standard flank position for RAPN has been fully standardized both with transperitoneal and retroperitoneal approach, that can be performed using both multiport systems (e.g., Da Vinci® Xi; Intuitive Surgical, Sunnyvale, CA, USA) and the novel Da Vinci® Single Port (SP) [7,8]. Conversely, the supine approach has been recently purposed with retroperitoneal access (namely, Supine Anterior Retroperitoneal Access [SARA]) [3]. The SARA approach has been described using the novel Da Vinci® SP, which received the approval for urologic surgery in United States by the Food and Drug Administration in 2018, and the Conformité Européenne trademark in 2024.

The availability of different approaches for RAPN hampers the conduction of rigorous comparisons, in order to test for concrete benefits of one relative to the others. In fact, the surgical approach might be key in defying its intra and postoperative outcomes (e.g., adverse events, ischemia time, surgical margins, postoperative pain) as well as the overall duration of the surgery (and overall operating room time usage). Unfortunately, such concept has never been addressed in a randomized prospective fashion, and the choice has always been mainly dependent on the expertise of the surgeons more than on the need of the patients. Assessing whether a certain approach significantly distinguishes itself from the others in terms of feasibility, safety and duration is of utmost interest and may significantly impact the common clinical practice.

Therefore, the objective of this study is to perform the first randomized clinical trial (RCT) addressing the best surgical approach for RAPN in the management of localized RCC. The novel SARA approach will be compared to the standard flank approach from the triple perspective of the anesthesiologist (e.g., intra-operative adverse events), the urologist (e.g., technical feasibility and oncological safety) and the patient (e.g., postoperative pain and postsurgical recovery). Hence, the name of the trial: K since concerns surgery of the kidney and 3 for the various aspects considered within.