An Update on Robotic-Assisted Partial Nephrectomy

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Kidney cancer is among the most lethal of urologic malignancies. The rising incidence of kidney cancer is attributable to greater detection of incidental small renal masses (≤4 cm) from increased use of radiographic imaging.1 The incidental detection of asymptomatic stage 1 lesions now accounts for more than half of all renal masses discovered. Decisions regarding the optimal treatment for the incidentally diagnosed small renal mass (SRM) are complex.

Traditionally, clinical stage 1 renal masses have been treated with surgical excision, most commonly radical nephrectomy (RN).2 However, concern that radical nephrectomy may predispose patients to the sequelae of chronic kidney disease, including increased cardiovascular risk and shortened overall survival, has led to the increased utilization of nephron-sparing procedures with the goal of preserving long-term renal function without affecting cancer control.3 Nephron-sparing surgery (NSS) is an established treatment for patients with SRM’s, providing excellent functional and oncologic outcomes.

Since the development of open partial nephrectomy (OPN), laparoscopic partial nephrectomy (LPN) has emerged as a minimally invasive technique that maintains the functional benefits of open NSS while conferring additional advantages specific to laparoscopic surgery. Nevertheless, some urologists are deterred from employing LPN for localized renal cell carcinoma (RCC) due to the technical difficulties posed by laparoscopy. As robotic-assisted surgery becomes more prevalent within the urologic community, this modality has been increasingly applied to NSS.

A prospective 2011 EORTC trial randomizing patients with tumors <5 cm 
to RN or partial nephrectomy (PN) provided the first level 1 evidence that oncologic efficacy is equivalent 
between treatment modalities (with intermediate term median follow 
up 9.3 years).4 Although utilization 
rates of NSS remain low, the AUA guidelines for the management of 
clinically localized renal tumors state that PN is the standard of care for cT1a lesions, and should be performed when technically feasible for T1b 
renal tumors.5

Although OPN remains the reference standard of care for clinically localized tumors, LPN emerged as a viable minimally invasive approach providing similar intermediate oncologic outcomes and faster postoperative recovery when compared to open techniques.3 Initially described in 2000,6 robotic-assisted laparoscopic prostatectomy (RALP) utilizing the da Vinci® Surgical System has been rapidly embraced by the urologic community.7

Due to increased access from the dissemination of RALP into community practice and a more rapid learning curve, robotic-assisted laparoscopic partial nephrectomy (RPN) has recently emerged as an alternative to LPN. Since its introduction, multiple series have demonstrated that with short-term 
follow up, RPN is safe and effective with equivalent oncologic outcomes to LPN.8 As a result, performance of RPN has dramatically increased over the past five years, and in 2008 was the fastest growing robotic procedure worldwide among any surgical specialty.9

The Pros and Cons of the Robotic Platform

LPN remains a technically challenging procedure requiring the surgeon to acquire advanced laparoscopic skills over a steep learning curve. Although equivalent 5- and 7-year oncologic efficacy has been reported,3 summaries of the current literature consistently demonstrate that LPN 
is associated with a greater warm ischemia time (WIT), increased risk of postoperative hemorrhage, and an increased risk of major urologic complications when compared with OPN.5

Limitations to LPN include two dimensional visualization, limited range of motion, and poor ergonomics due to the use of rigid instrumentation, which make tumor excision and reconstruction under minimal ischemia time challenging. While laparoscopic and robotic approaches show similar results with regard to convalescence and perioperative morbidity, advantages afforded by the robotic platform include stereoscopic visualization and enhanced dexterity (EndoWrist; Intuitive 
Surgical, Inc., Sunnyvale, Calif.) facilitating the ability to perform precise reconstruction. 

Disadvantages to the robotic platform are primarily decreased tactile 
feedback, which can be overcome using learned visual cues, and prohibitive instrumentation and maintenance costs. Using cost models, Mir et al compared OPN, LPN, and RPN using sensitivity 
analyses, and reported that of the three surgical approaches, LPN was the most cost effective due to shorter length of hospital stay compared to OPN and reduced instrumentation cost compared to RPN.10