Robotic-assisted partial nephrectomy (RPN) has exhibited superiority to laparoscopic partial nephrectomy (LPN) for small renal tumors; thus, the recent trend in minimally invasive partial nephrectomy has shifted toward RPN.1-3 Robotic-assisted partial nephrectomy embrace a brief learning curve and has advantages in all the parameters of warm ischemia time (WIT), conversion to open surgery, surgical margins, perioperative complications, change of renal function, and length of hospital stay (LOS).1-4 We report the perioperative outcomes of RPN surgery in a single center in Saudi Arabia.
Methods
This is a retrospective study of the electronic records of patients who underwent RPN at King Faisal Specialist Hospital and Research Center, Riyadh, Kingdom of Saudi Arabia, between January 2008 and January 2018. The Institution Review Board approved the project. The study was conducted according to principles of Helsinki Declaration.
Inclusion criteria involved all patients who underwent RPN of any age, gender or indication. No exclusion criteria were applied.
Surgical technique
The Si robotic system (da Vinci® Surgical System, da Vinci® Si, USA) was used for all RPNs. A 3-arm or 4-arm robotic approach was used according to the surgeon’s preference. The kidney was mobilized entirely outside Gerota’s fascia, and the tumor with intact peri-renal fat was localized and scored using electrocautery and the adjacent kidney de-fatted. Intraoperative laparoscopic ultrasound was used in some of the recent cases. Sharp resection of the tumor was performed using robotic scissors. Sutured renorrhaphy was carried out in 2 stages: the bed of the resection was sutured in a running fashion, using monofilament absorbable sutures or self-locking barbed suture (V-Loc 90; Covidien, Mansfield, Massachusetts) according to the surgeon’s preference, and then the partial nephrectomy defect was closed by interrupted monofilament suture. All cases were video-recorded for quality assurance and review if necessary. The reported parameters included patients’ demographics; tumor characteristics, including size, location, radius exophytic nearness anterior/posterior location (RENAL) nephrometry score, stage, histopathology type, grade, and surgical margin; operative details, including operative time, WIT, estimated blood loss (EBL); and postoperative outcomes, including day one serum creatinine, estimated glomerular filtration rate (eGFR) change, LOS, and complications. We used the Modification of Diet in Renal Disease Study Group equation (MDRD) to calculate eGFR.5 To assess the progress of learning of the surgeons, we divided the patients into 2 nearly equal chronological groups and compared their characteristics and perioperative outcomes. To review the literature, we conducted a PubMed search for citations up to December 2017 using the term “robotic partial nephrectomy” and restricted the output to “English Language and Human”. We compared perioperative outcomes of publications that included a number of patients similar to our series.
We used the program SPSS version 20 (IBM Corporation, USA) for the statistical analysis. We utilized descriptive statistics reporting the median, standard deviation (SD), minimum and maximum values for continuous variables and numbers and percentages for categorical values. In subgroup analysis, we compared continuous variables with analysis of variance reporting mean and SD values and for categorical values, we utilized Fisher exact test. Significant results were reported if p<0.05.
Results
A total of 101 consecutive patients underwent RPN (Table 1), between January 2008 and January 2018. Four urologists without prior experience in RPN performed 85 procedures (Figure 1). Patients were diagnosed with a small renal mass either incidentally (n=72; 71.3%) or due to symptoms (pain or hematuria; n=29; 28.7%). Clinical staging showed that 84 (84%) patients had a stage T1aN0M0 tumor, whereas 16 patients had a stage of T1bN0M0. Eighty tumors (79.2%) were solid and 20 (19.8%) were complex renal cysts. One patient had RPN for a non-functioning upper renal moiety.
Table 1
Surgical outcomes of RPN are shown in Table 1. Four patients (4%) needed an intraoperative transfusion of a single unit of blood. Nine patients (8.9%) were converted to open partial nephrectomy because of bleeding or lack of progress in dissection. During RPN, 12 patients (11.9%) underwent no renal vascular clamping, whereas warm ischemia occurred in 89 patients (88.1%) by selective arterial clamping. Preoperatively, 96 (95%) patients had an eGFR value greater than 60 ml/min/1.77m2; postoperatively, none of these patients experienced a decrease in eGFR below 60 ml/min/1.77m2. Of all patients; however, 16 (15.8%) experienced a decrease in eGFR of ≤15%.
Table 2 shows a comparison between patients without and with a decrease in eGFR of ≤15%. In patients who demonstrated the decrease, the only significant risk factors were a longer procedure time and the presence of a complication. This decrease occurred though there was a significantly better preoperative eGFR in those patients. Pathological examination of the tumors revealed 68 pT1a (68%), 8 pT1b (8%), 6 pT3a (6%), and 19 benign lesions (18.8%), including 8 angiomyolipomas (7.9%), 7 oncocytomas (6.9%), and 4 other lesions (4%). A positive surgical margin was documented in 5 cases (5%). One patient had a tumor rupture/spillage; this patient remained free of disease after 30 months.
Table 2
Table 3 shows a comparison between patients without and with a PSM. The only significant difference was a higher mean age in the PSM group. Postoperatively, minor complications (Clavien-Dindo grade I–II) were encountered in 16 (15.8%) patients. Only 3 (3%) patients had a complication grade ≥III, Clavien-Dindo classification. One had an arteriovenous fistula requiring embolization 3 weeks postoperatively, one had a diaphragmatic injury requiring intraoperative repair, and one patient developed atrial fibrillation requiring intensive care admission. A total of 73 (73%) patients achieved a trifecta of freedom from any complication, negative surgical margins, and ischemia time ≤25 min. The outcomes of WIT, EBL, conversion to open and trifecta achievement were not different between the first and subsequent 50 patients (Table 4). Significantly longer operative time and more decrease in eGFR were found in the latter group.
Table 3
Table 4
Discussion
This initial experience of RPN in one Middle Eastern country demonstrates outcomes comparable to Western series reporting on at least 100 RPN (Tables 5-7).1,6-26 Our initial 101 cases had a slightly lower median renal score of 6 and a mean score of 5.8 compared to 22 studies reporting a median renal score between 7 and 9 and a mean score ranging between 6 and 8.2. This tendency to select less complex renal masses for RPN reflects the initial experience of our surgeons embarking on the procedure. Tumor size, however, in the current series was comparable to other studies. The median tumor size in the current series was 3 cm and the mean was 3.1 cm compared to a range of median size of 2 to 5 cm and mean of 2.4 to 3.3 cm reported in other studies. The smallest tumor in the current series was 1.3 cm in diameter, whereas in other studies the smallest reported tumor was 0.9 cm. Remarkably, operative and postoperative parameters gauging the surgeons’ skills in performing RPN was on par with those reporting larger series beyond the learning curve. The median WIT in the current series was 17 minutes and the mean was 17.6 in comparison to other studies with a median range of WIT of 15-26 minutes and a mean range of 15.7-25.5 minutes. The off-clamp RPN constituted 11.9% of the current series compared to a range of 0-38% reported by others. The operative time, EBL, and LOS were comparable to other reported series. The current series had 5% positive surgical margin (PSM) compared to a range of 0-9.9% reported by others. Except for older age, we found no significant risk factor associated with PSM. Any complication was reported only in 3% of cases. This favorable outcome is among the lowest reported by other series, ranging between 0.4% and 39%. The development of a complication or the longer procedure time were risk factors for a decrease of eGFR ≤15% even in face of a higher preoperative eGFR. We did not factor in the analysis risk factors for decreased eGFR such as diabetes, hypertension, dyslipidemia or nephrotoxic medications. As these risk factors likely contributed to the preoperative eGFR, we think that for the purpose of a short-term perioperative analysis of eGFR change as a surrogate for quality of surgery, our conclusions are accurate. To evaluate the impact of RPN on renal function in the long term, these risk factors among other confounders of the renal functional reserve are worthwhile to study. The current series reported the highest trifecta, 73%, in comparison to the 5 studies reporting a trifecta outcome ranging between 37.5% and 72.2%. On a different note, the conversion rate to open surgery was the second most common in all studies reviewed. Conversion to open partial nephrectomy in the current series was 8.9%, and no case was converted to nephrectomy. In comparison, other series reported conversion to open nephrectomy, either to partial or total, in 0-11.7%.
Table 5
Enlarge this image.Tumor characteristics: Comparison of current series with others reporting ≥100 patients.
Table 6
Table 7
Enlarge this image.Postoperative outcome: Comparison of current series with others reporting ≥100 patients.
Although the number of patients who underwent RPN was relatively small per surgeon and spanning a long period compared to higher-volume centers, the results indicate that the number of surgeries needed to gain the cumulative learning experience is small. Comparison of the first 50 cases with the subsequent surgeries showed no significant difference in the WIT, EBL, complication rate, conversion to open surgery, PSM or achievement of a trifecta benchmark all of which indicate no appreciable change in the quality of surgery over the protracted period. Admittedly the duration of surgery increased, and this may have contributed more significant decrease in post-operative eGFR. The longer duration of surgery might be due to a more difficult surgery beyond the actual time and skill spent to excise the tumor from the kidney. Different factors contributed to the favorable outcome of the current series. The first factor was that all surgeons had prior experience with laparoscopic partial nephrectomy and robotic nephrectomy. These findings on the transition from laparoscopic to robotic partial nephrectomy are similar to other reports from single surgeon series at high-volume centers.27 Second, 2 experienced surgeons teamed up in a single case. We believe it is important for outcomes of RPN to be reported from various parts of the world, thus attesting to the generalizability of the robotic technique as well as bringing the benefits of robotic technology to Middle Eastern patients. Study limitations include the retrospective design and small cohort size. Future studies from our region may include long-term functional and oncological outcomes of RPN.
In conclusions, our initial experience of robotic partial nephrectomy is associated with a surgical outcome comparable to that reported by higher volume centers. The favorable outcome reflects that the number of surgeries needed to gain the cumulative learning experience is small, even with a protracted course of time.
Acknowledgment
We would like to thank Elsevier Publishing Company, Amsterdam, Netherlands (webshop.elsevier.com/languageservices/languageediting) for English language editing.
Disclosure. Authors have no conflict of interests, and the work was not supported or funded by any drug company.
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