Robotics has revolutionized urologic surgery for the last 2 decades, including partial nephrectomy (PN). For small renal masses, both the AUA and National Comprehensive Cancer Network guidelines recommend PN (Figure 1) for all T1 lesions.^1,2 Since then, urologists have been chasing the trifecta which includes improving oncologic outcomes, preserving renal function, and avoiding perioperative complications. The technical limitations of laparoscopic PN (LPN) made the trifecta attainable for only highly experienced laparoscopic surgeons. The first robotic-assisted PN (RAPN) was reported by Gettman et al in 2004.³ Since then, minimally invasive PN has become more prevalent, especially with increased experience in robotic surgery leading many surgeons across the world to now treat clinical T2 and T3 lesions with RAPN. Another potentiating factor for RAPN becoming the standard of care is education. Residents and fellows are proficient in much of the procedure for RAPN prior to graduation. One study showed that RAPN can safely be taught in a stepwise standardized procedure and has no negative effect on reaching the trifecta during the training.⁴

The Complexity of Renal Mass Management

The paradigm shifts in the AUA guidelines to expand the role for PN over radical nephrectomy (RN) pushed the evolution of RAPN. The AUA guidelines have been dedicated to avoiding the overuse of RN but maintaining safe oncologic practices. As the field became committed to nephron-sparing surgery, so did the desire to achieve this with minimally invasive surgery. Robotic surgery shortened the learning curve and facilitated greater uptake of minimally invasive nephron-sparing surgery in otherwise complex renal masses which traditionally underwent RN. While robotics offered improvements to renal surgery, there was concern that technology was driving therapeutic management. While the number of patients on active surveillance increased, so did RAPN. Figure 2 from Shah et al displays the shift to RAPN was greater than that of LPN and active surveillance.⁵ This was balanced by studies that showed RAPN carried low morbidity, and no study to date has shown improved overall survival of active surveillance vs PN.⁶

Advantages of RAPN

One of the most comprehensive reviews by Cacciamani et al looked at both open PN (OPN) and LPN vs RAPN and showed warm ischemia time was less in OPN, while hospital stay, readmission rates, transfusions, and complications were all decreased in RAPN. As part of this assessment, a meta-analysis of over 51 studies showed RAPN had shorter warm ischemia time, fewer complications, less conversion to open surgery, decreased positive margins, fewer transfusions, and improved renal function over LPN.⁷ Another large, prospective, multicenter trial demonstrated superiority of RAPN over LPN and OPN. While this study was primarily focused on how resection technique affected surgical margins, the secondary outcomes unequivocally demonstrated that surgical approach greatly impacted achieving the PN trifecta. And again, RAPN outperformed both OPN and LPN.⁸

Bigger, Bolder, Better?

As surgeons became more experienced in RAPN, resection of pT2 and pT3 masses became more popular. This was fueled by the addition of improved HD robotic ultrasound capability, 3D imaging reconstruction, and vascular assessment with indocyanine green. The 3D reconstruction platforms use machine learning to better delineate the relationship between vascular and renal anatomy. Studies using the technology showed shorter operating times, decreased blood loss, and lowered clamp times, even in less experienced surgeons (Figure 3).⁹ One series by Beksac et al highlighted patients with solitary kidneys and described their experience for PN with clinical T2 and T3 masses. They compared 20 RAPNs and 15 OPNs with a tumor size of 6 cm and a R.E.N.A.L. (for radius, exophytic/endophytic, nearness of tumor to collecting system, anterior/posterior, location relative to polar line) score of 9. Over 80% of the patients in the study had clinical T3 disease. The positive surgical margin rates were 20% vs 15% favoring the RAPN group. Only 1 patient in each group needed temporary dialysis. Major complication rate, readmission rate, and longer hospital stay were significantly higher in patients who had OPN.¹⁰ The retrospective study from the Robotic Surgery for Large Mass (ROSULA) collaborative group confirmed feasibility of reaching the PN trifecta with RAPN in complex tumors. All patients had a R.E.N.A.L. nephrotomy score of 10 or greater and localized disease. With 5 years of oncologic follow-up, RAPN vs minimally invasive RN showed comparable cancer-specific survival and overall survival rates (Figure 4; pT3). The group showed no increased complications with RAPN and no compromise of safety outcomes.¹¹

RAPN has taken over as the gold standard for renal mass treatment. Minimally invasive surgery using robotics improved the ability to perform complicated dissection, identify vascular control using indocyanine green, and enhance oncologic outcomes with decreased complications. With the resurgence of retroperitoneal surgery, single-port robotics is next in line for RAPN evolution as it allows access to a small space with ease and has outcomes comparable to multiport surgery.¹² Not far behind will be artificial intelligence navigation to the tumor using integrated imaging to both guide the surgeon and prevent error.