Yung K. Tan

Radiofrequency Ablation Versus Partial Nephrectomy in Patients with Solitary Clinical T1a Renal Cell Carcinoma: Comparable Oncologic Outcomes at a Minimum of 5 Years of Follow-Up

BACKGROUND Long-term comparative outcomes for radiofrequency ablation (RFA) versus partial nephrectomy (PN) for the primary treatment of clinical T1a renal cell carcinoma (RCC) have not previously been reported. OBJECTIVE Report comparative 5-yr oncologic outcomes for RFA versus PN in patients with clinical T1a RCC. DESIGN, SETTING, AND PARTICIPANTS Observational single-institution cohort study, involving consecutive patients with a solitary histologically confirmed T1a RCC treated by RFA or PN and followed for a minimum of 5 yr. Those presenting with synchronous multiple, metachronous, bilateral, and/or metastatic disease, a history of hereditary RCC syndromes, a family history of RCC, and with post-treatment follow-up <5 yr were excluded from analysis. MEASUREMENTS The Kaplan-Meier method was used to determine 5-yr overall survival (OS), cancer-specific survival (CSS), local recurrence-free survival (local RFS), overall disease-free survival (DFS), and metastasis-free survival (MFS) for RFA versus PN. Survival curves were compared using the log-rank test. A p value ≤ 0.05 was considered statistically significant. RESULTS AND LIMITATIONS A total of 37 patients in each group met the selection criteria. The RFA cohort was significantly older and had more advanced comorbidities, but other patient characteristics were similar. For RFA versus PN, median follow-up was 6.5 yr (interquartile range [IQR]: 5.8-7.1) versus 6.1 yr (IQR: 5.4-7.3) (p = 0.68), respectively. The 5-yr OS was 97.2% versus 100% (p = 0.31), CSS was 97.2% versus 100% (p = 0.31), DFS was 89.2% versus 89.2% (p = 0.78), local RFS was 91.7% versus 94.6% (p = 0.96), and MFS was 97.2% versus 91.8% (p = 0.35), respectively. Study limitations are retrospective data analysis, loss to follow-up, limited statistical power, and limited generalizability of our data. CONCLUSIONS In appropriately selected patients, RFA is an effective minimally invasive therapy for the treatment of cT1a RCC, yielding comparable long-term oncologic outcomes to nephron-sparing surgery.

Long-Term Outcomes of Renal Tumor Radio Frequency Ablation Stratified by Tumor Diameter: Size Matters

PURPOSE Renal tumor size influences the efficacy of radio frequency ablation but identification of confident size cutoffs has been limited by small numbers and short followup. We evaluated tumor size related outcomes after radio frequency ablation for patients with adequate (greater than 3 years) followup. MATERIALS AND METHODS We identified 159 tumors treated with radio frequency ablation as primary treatment. Disease-free survival was defined as the time from definitive treatment to local recurrence, detection of metastasis or the most recent imaging showing no evidence of disease. Patients were evaluated with contrast enhancing imaging preoperatively, and at 6 weeks, 6 months and at least annually thereafter. RESULTS Median tumor size was 2.4 cm (range 0.9 to 5.4) with a median followup of 54 months (range 1.5 to 120). Renal cell carcinoma was confirmed in 72% of the 150 tumors that had pre-ablation biopsy (94%). The 3 and 5-year disease-free survival was comparable at 92% and 91% overall, and was dependent on tumor size, being 96% and 95% for tumors smaller than 3.0 cm and 79% and 79%, respectively, for tumors 3 cm or larger (p=0.001). Most failures (14 of 18) were local, either incomplete ablations or local recurrences. This is an intent to treat analysis and, therefore, includes patients ultimately found to have benign tumors, although outcomes were comparable in patients with cancer. CONCLUSIONS Radio frequency ablation treatment success of the small renal mass is strongly correlated with tumor size. Radio frequency ablation provides excellent and durable outcomes, particularly in tumors smaller than 3 cm. Of tumors 3 cm or larger, approximately 20% will recur such that alternative treatment techniques should be considered. However, most treatment failures are local and are often successfully treated with another ablation session.

Perioperative Comparison of Robotic Assisted Laparoendoscopic Single-Site (LESS) Pyeloplasty Versus Conventional LESS Pyeloplasty

BACKGROUND Conventional laparoendoscopic single-site (C-LESS) pyeloplasty is technically challenging due to instrument clashing, loss of triangulation, and difficulty sewing. Application of the da Vinci S or Si robotic platforms could potentially overcome these challenges. OBJECTIVE Compare our initial experience with robotic assisted laparoendoscopic single-site (R-LESS) pyeloplasty to our latter experience with C-LESS pyeloplasty (ie, after the initial 15 patients). DESIGN, SETTING, AND PARTICIPANTS This single-institution retrospective observational cohort study involved consecutive patients who presented with symptomatic ureteropelvic junction obstruction and who were deemed suitable for single-incision pyeloplasty by the treating surgeon. MEASUREMENTS Demographic, clinical, perioperative, and early postoperative comparative outcomes. RESULTS AND LIMITATIONS Ten patients each underwent R-LESS or C-LESS pyeloplasty by a single surgeon between March 2009 and July 2011. For R-LESS and C-LESS groups, age, gender distribution, body mass index, proportion of patients with prior abdominal surgery, estimated blood loss, and hospital length of stay were statistically similar. Mean operative time was significantly longer for R-LESS (226 vs 188 min; p=0.007). C-LESS pyeloplasty alone required an accessory port for the anastomosis in 10 of 10 cases. Two conversions to standard laparoscopy and two postoperative complications occurred in 3 of 10 patients in the C-LESS group, compared with no conversions and one postoperative complication in the R-LESS group (p=0.26). Study limitations are a retrospective design, a modest number of patients, and a lack of quantification of subjective outcomes such as instrument clashing and maneuverability. CONCLUSIONS Adaptation of the da Vinci Si robotic surgical platform to laparoendoscopic single-site pyeloplasty appears to reduce the physical learning curve for this complex procedure. Future prospective, comprehensive evaluation of additional outcomes including subjective parameters, cosmesis, and longer term functional outcomes will help better define its role in minimally invasive dismembered pyeloplasty and better estimate its associated learning curve.

Radiofrequency Ablation of Incidental Benign Small Renal Mass: Outcomes and Follow-up Protocol

OBJECTIVE To review our 10-year experience with radiofrequency ablation, focusing on the outcomes for the incidental benign renal tumor. Tumor ablation is an alternative minimally invasive approach for the treatment of small renal masses (SRMs), with published series appropriately emphasizing the outcomes for the renal cell carcinoma subset of treated tumors. However, just as with partial nephrectomy, approximately 20% of SRMs are benign. The intermediate- to long-term outcome of the incidentally ablated benign tumor and its appropriate follow-up protocol is unknown. METHODS All SRMs treated with temperature-based radiofrequency ablation from 2001 to 2011 were reviewed. Of a total of 280 enhancing SRMs biopsied at radiofrequency ablation, 47 were confirmed as benign tumors. Ablation success was defined as the lack of enhancement on the initial postablation axial imaging. Recurrence was defined as tumor growth and enhancement on follow-up axial imaging. RESULTS Of the 47 benign tumors, 32 were treated percutaneously and 15 laparoscopically. The histologic biopsy finding was angiomyolipoma in 10 and oncocytoma in 37. The median tumor size was 2 cm (range 1-3.6), and the mean follow-up was 45 months. No recurrences developed, and all lesions required only 1 treatment session. The median pre- and postoperative glomerular filtration rate was 77 mL/min/1.73 m(2) (range 39-137) and 68 mL/min/1.73 m(2) (range 36-137). The present study was limited by its retrospective nature and small sample population. CONCLUSION Radiofrequency ablation of SRMs <3.5 cm found to be benign on concurrent biopsy can be efficaciously treated with a single treatment session. Long-term follow-up imaging might not be required if successful ablation is determined at the initial post-treatment cross-sectional imaging study.

First Place: Renal Oxygenation During Robot-Assisted Laparoscopic Partial Nephrectomy: Characterization Using Laparoscopic Digital Light Processing Hyperspectral Imaging

UNLABELLED Abstract Background and Purpose: Digital light processing-based hyperspectral imaging (DLP(®)-HSI) was adapted for use during laparoscopic surgery by coupling the spectral illumination source with a conventional laparoscopic light guide and incorporating a customized digital charge-coupled device camera for image acquisition. The system was used to characterize renal oxygenation during robot-assisted laparoscopic partial nephrectomy (RALPN) in humans. PATIENTS AND METHODS After Institutional Review Board approval, laparoscopic DLP-HSI was performed in consecutive patients undergoing RALPN at our institution. Time trends in relative tissue oxygen saturation (%HbO2) were descriptively analyzed. Associations between %HbO2 and patient age, comorbidities, and estimated glomerular filtration rate (eGFR) were investigated using the Kendall tau test. RESULTS Laparoscopic DLP-HSI was performed in 18 patients between May 2011 and February 2012. Median (interquartile range; IQR) age was 55.9 (49-67.5) years. Of the patients, 10/18 (56%) were men and 12/18 (66.7%) had a history of hypertension, diabetes, and/or tobacco use. Median (IQR) %HbO2 before, during, and after ischemia was 60.8% (57.9-68.2%), 53.6% (46.8-55.1%), and 61.5% (54.9-67.6%), respectively. Baseline %HbO2 was inversely associated with preoperative eGFR (τ=-0.38; P=0.036), and eGFR at most recent follow-up (τ=-0.38; P=0.036). Baseline or ischemic %HbO2 did not correlate with hypertension, diabetes, and/or tobacco history. Younger patients (<56 years) had a lower median baseline %HbO2 (P=0.07) and a higher median preoperative eGFR (P=0.038), than their older counterparts. CONCLUSION The laparoscopic HSI system successfully characterized dynamic changes in renal oxygenation during RALPN. Intraoperative laparoscopic HSI outcomes have the potential to predict postoperative individual kidney function.

Robot-assisted laparoendoscopic single-site pyeloplasty: technique using the da Vinci Si robotic platform.

Conventional laparoscopic dismembered pyeloplasty (LP) is an established alternative to open pyeloplasty given equivalent intermediate-term outcomes and decreased morbidity. Laparoendoscopic single-site (LESS) pyeloplasty has the potential to further decrease the morbidity of LP, while yielding superior cosmesis. It is, however, technically very challenging even with the use of an accessory port, largely because of the difficulty of intracorporeal suturing through a single umbilical incision. Application of the da Vinci robotic surgical platform to LESS pyeloplasty (R-LESS) has the potential to overcome these limitations. We describe our technique for R-LESS pyeloplasty using the da Vinci Si robot. We have found that use of the robotic system in conjunction with certain technique modifications helps to reduce the technical difficulty of LESS pyeloplasty and to shorten the physical learning curve associated with the procedure.

In vitro comparison of prototype magnetic tool with conventional nitinol basket for ureteroscopic retrieval of stone fragments rendered paramagnetic with iron oxide microparticles

PURPOSE We developed a prototype magnetic tool for ureteroscopic extraction of magnetized stone particles. We compared its efficiency for retrieving magnetized calcium oxalate monohydrate stone particles with that of a conventional nitinol basket from the pelvi-collecting system of a bench top ureteroscopic simulator. MATERIALS AND METHODS Iron oxide microparticles were successfully bound to 1 to 1.5, 1.5 to 2 and 2 to 2.5 mm human calcium oxalate monohydrate stones. Several coated fragments of each size were implanted in the collecting system of a bench top ureteroscopic simulator. Five-minute timed stone extraction trials were performed for each fragment size using a back loaded 8Fr magnetic tool mounted on a 0.038-inch guidewire or a conventional basket. The median number of fragments retrieved per timed trial was compared for the magnetic tool vs the basket using the Mann-Whitney U test. RESULTS For 1 to 1.5 mm fragments the median number retrieved within 5 minutes was significantly higher for the prototype magnetic tool than for the nitinol basket (9.5 vs 3.5, p = 0.03). For 1.5 to 2 mm fragments the magnetic tool was more efficient but the difference in the number of fragments retrieved was not statistically significant (9.5 vs 4.5, p = 0.19). For 2 to 2.5 mm fragments there was no difference between the instruments in the number retrieved (6 per group, p = 1.0). CONCLUSIONS The prototype magnetic tool improved the efficiency of retrieving stone particles rendered paramagnetic that were less than 2 mm but showed no advantage for larger fragments. This system has the potential to decrease the number of small retained fragments after ureteroscopic lithotripsy.

Minimally Invasive Pyeloplasty in Horseshoe Kidneys with Ureteropelvic Junction obstruction: A case series

BACKGROUND AND PURPOSE Horseshoe kidney is an uncommon renal anomaly often associated with ureteropelvic junction (UPJ) obstruction. Advanced minimally invasive surgical (MIS) reconstructive techniques including laparoscopic and robotic surgery are now being utilized in this population. However, fewer than 30 cases of MIS UPJ reconstruction in horseshoe kidneys have been reported. We herein report our experience with these techniques in the largest series to date. MATERIALS AND METHODS We performed a retrospective chart review of nine patients with UPJ obstruction in horseshoe kidneys who underwent MIS repair at our institution between March 2000 and January 2012. Four underwent laparoscopic, two robotic, and one laparoendoscopic single-site (LESS) dismembered pyeloplasty. An additional two pediatric patients underwent robotic Hellstrom repair. Perioperative outcomes and treatment success were evaluated. RESULTS Median patient age was 18 years (range 2.5-62 years). Median operative time was 136 minutes (range 109-230 min.) and there were no perioperative complications. After a median follow-up of 11 months, clinical (symptomatic) success was 100%, while radiographic success based on MAG-3 renogram was 78%. The two failures were defined by prolonged t1/2 drainage, but neither patient has required salvage therapy as they remain asymptomatic with stable differential renal function. CONCLUSIONS MIS repair of UPJ obstruction in horseshoe kidneys is feasible and safe. Although excellent short-term clinical success is achieved, radiographic success may be lower than MIS pyeloplasty in heterotopic kidneys, possibly due to inherent differences in anatomy. Larger studies are needed to evaluate MIS pyeloplasty in this population.

Novel Iron Oxide Microparticles Used to Render Stone Fragments Paramagnetic: Assessment of Toxicity in a Murine Model

PURPOSE We developed novel peptide coated iron oxide supraparamagnetic microparticles that bind to calcium stones, allowing for extraction of these stones with magnetic tools. Urothelial and fibroblast cell lines show minimal to no toxicity when exposed to the particles. Before clinical evaluation, assessment of the in vivo systemic toxicity of the microparticles was required. This was studied in a murine model. MATERIALS AND METHODS A total of 64 mice were exposed to different concentrations of microparticles (0.5, 1 or 5 mg/dl) intravesically or intravenously via the tail vein. Mice were sacrificed at different intervals (days 1, 3, 28 and 84). Representative samples from the brain, lung, heart, kidney and liver were evaluated histologically at each time point. The tissue distribution pattern of the particles and any degree of inflammation was noted by a clinical pathologist. Liver function tests were also performed at similar intervals. RESULTS All mice survived until the assigned end point and appeared healthy after exposure to microparticles. In the bladder installation group no particles were seen in any organ regardless of the particle concentration instilled. In the intravenous instillation group there was tissue distribution in the liver and to a lesser extent in the lung. There was mild inflammation in the liver and lung, which was dose dependent. CONCLUSIONS Novel iron oxide supraparamagnetic microparticles used to render stone fragments paramagnetic in the urinary collecting system did not appear to cross intact urothelial membranes. When introduced systemically, they led to minimal inflammatory changes, predominantly in the liver and lung. Additional long-term studies are required.

Laparoendoscopic single-site (LESS) pyeloplasty for horseshoe ureteropelvic junction obstruction.

This report suggests that laparoscopic single-site pyeloplasty of uteropelvic junction obstruction associated with horseshoe kidney is feasible, safe, and effective in select patients.