Partial nephrectomy (removing only the tumor and a small rim of surrounding tissue, rather than the entire kidney) is the preferred treatment for small kidney tumors. Preserving as much healthy kidney tissue as possible protects long-term kidney function and reduces the risk of chronic kidney disease later in life.
Surgeons initially performed partial nephrectomy through open incisions, but minimally invasive laparoscopic approaches emerged as an alternative. While laparoscopy offers smaller incisions and faster recovery, it is technically demanding and has discouraged many surgeons, leading some to instead perform full kidney removal (radical nephrectomy) even when partial removal would have been appropriate.
Robotic surgical systems such as the da Vinci system offer wristed instruments that mimic the movement of the human hand with greater precision and range of motion than standard laparoscopic tools. Surgeons already experienced with robotic prostatectomy may find it easier to apply these skills to kidney tumor removal.
This study reports the first 100 robot-assisted partial nephrectomy (RAPN) operations performed at Fox Chase Cancer Center, providing a detailed look at surgical outcomes, tumor complexity, and kidney function preservation in a real-world setting.
All 100 procedures were performed using the da Vinci S surgical system by four different surgeons over a 21-month period. A three-arm robotic technique was used, with port positions tailored to the location of each tumor and the renal hilum (the central entry point for blood vessels and the ureter).
Intraoperative ultrasound was used to confirm tumor margins and guide tissue scoring with electrocautery. Warm ischemia (temporarily clamping the kidney's blood supply while the tumor is removed and the kidney is repaired) was used in 88% of cases. The kidney was repaired using layered sutures and absorbable hemostatic materials.
The R.E.N.A.L. nephrometry scoring system was used to objectively quantify the complexity of each tumor's anatomic location. This system rates tumors on five features (size, depth, nearness to collecting system, anterior/posterior position, and location relative to polar lines) to create a standardized complexity score.
Tumor complexity ranged widely: 47.9% of tumors scored in the low-complexity range, 45.7% in the medium range, and 6.4% in the high range. Nearly half of tumors were more than 50% buried within kidney tissue, and over 60% were within 7mm of the kidney's collecting system, indicating a technically demanding case mix.
The median tumor size was 2.8 cm (range 1.0 to 8.0 cm). Median warm ischemia time was 25.5 minutes, which compares favorably to published laparoscopic series. Median operating room time was 203 minutes and median estimated blood loss was 127 ml, with no intraoperative transfusions required.
Of 107 tumors removed, 87 (81%) were malignant renal cell carcinomas, including clear cell (67%), papillary (24%), chromophobe (6%), and collecting duct (3%) types. The remaining 20 tumors were benign, including oncocytomas, benign cysts, and angiomyolipomas.
Only 5 of 87 malignant tumors (5.7%) had microscopically positive surgical margins on final pathology. All five patients elected surveillance over reoperation, and no patient developed radiologic evidence of tumor recurrence during a mean follow-up of 12.7 months.
Two of the 100 planned RAPN operations required conversion to open surgery: one due to breathing difficulties with the pneumoperitoneum (air in the abdominal cavity needed for laparoscopic surgery), and the other because severe liver enlargement blocked access to the tumor. The 2% conversion rate is comparable to published laparoscopic partial nephrectomy series.
Preserving kidney function is a primary goal of partial nephrectomy. The study measured glomerular filtration rate (GFR), a standard measure of kidney function, before and after surgery. The mean change in GFR after surgery was an improvement of 6.32 ml/min/1.73m2, though this average change was not statistically significant.
Four patients underwent the procedure on both kidneys at separate times (bilateral tumors). Even in these challenging cases, kidney function was maintained, with an average GFR improvement of 4.2 ml/min/1.73m2 from initial presentation through recovery from the second procedure.
The preservation of kidney function in this series was comparable to or better than published laparoscopic series. The shorter warm ischemia time with RAPN (median 25.5 minutes vs. reported 30.7 minutes for laparoscopy) may contribute to better kidney preservation, as longer ischemia times are associated with more kidney injury.
Eleven percent of patients in this series already had stage III, IV, or V chronic kidney disease before surgery, meaning they started with significantly reduced kidney function. For these vulnerable patients, preserving even a small amount of additional kidney function carries important health benefits.
Complications within 30 days of surgery were recorded and graded using the standardized Clavien classification system. This system grades complications from I (minor, requiring no intervention) through V (death). Using a standardized scale allows meaningful comparison between institutions and surgical approaches.
There were 5 major complications (grade III) requiring intervention: a pulmonary embolism treated with an IVC filter, a fluid collection requiring drainage, a delayed bleeding pseudoaneurysm requiring embolization, a kidney stone causing a urine leak requiring stenting, and a port site bleed requiring sutures and blood transfusion.
The overall complication rates (6% major, 5% minor) compare favorably with published laparoscopic series, which report major complication rates around 9%. The urine leak rate of 2% was also better than the 3.1% rate reported in a large laparoscopic series. One death occurred due to a myocardial infarction during port site closure in a patient with a pre-existing cardiac stent.
The series also included technically complex tumors such as those touching the renal hilum (the central vascular bundle), where surgery carries higher risks. The acceptable complication rates despite this complexity suggest that experienced robotic surgeons can safely extend the procedure to more challenging cases.
The study placed its results in the context of prior RAPN series and the landmark comparison of 1800 laparoscopic versus open partial nephrectomies by Gill et al. When matched for tumor size, RAPN in the current series showed shorter warm ischemia times (25.5 minutes vs. 30.7 minutes) compared to laparoscopic partial nephrectomy.
A key advantage of using an objective scoring system (nephrometry) is that it allows readers and future researchers to understand how complex the tumors were. Previous comparisons of surgical techniques were limited because tumor complexity was not standardized, making it difficult to know if differences in outcomes reflected the technique or the difficulty of the cases.
Critics argued early on that robotic partial nephrectomy offered no advantage over standard laparoscopy. However, the authors argue that robotic assistance enables surgeons to tackle more anatomically complex tumors that might otherwise require open surgery or full kidney removal, extending the benefits of minimally invasive surgery to a broader patient population.
The study acknowledged the need for longer follow-up to confirm durable cancer control and kidney function preservation. Randomized prospective studies comparing open, laparoscopic, and robotic partial nephrectomy would be the most rigorous way to determine which approach is optimal for which patients.
This study, representing the largest single-institution series of robot-assisted partial nephrectomy at the time of publication, demonstrated that RAPN is safe and technically feasible even for tumors of moderate and high anatomical complexity.
The pathological and functional results were comparable to open and laparoscopic nephron-sparing surgery, with an acceptable positive margin rate and excellent kidney function preservation. The short median hospital stay of 3 days reflects the minimally invasive nature of the procedure.
Standardizing the reporting of tumor complexity using scoring systems like nephrometry is essential for meaningful comparisons between surgical series. As robotic technology continues to evolve and surgeon experience grows, RAPN may become the preferred approach for nephron-sparing surgery in many centers.
Preserving kidney function in kidney cancer patients is not only about avoiding dialysis. Chronic kidney disease is associated with increased risk of heart disease and early death, making the long-term functional outcome of kidney surgery an important measure of patient wellbeing beyond cancer control.