332 HYALURONAN SECRETION AS A CELL DEFENSE MECHANISM DURING EARLY CALCIUM OXALATE ASSOCIATED INJURY

329

Management of renal angiomyolipoma: medical and cost effectiveness comparison of selective embolization and surgery

330

Laparoscopic endoscopic single site surgery (LESS) tumour nephrectomy

Huyghe E.1, Delchier M.C.2, Mottier M.L.3, Malavaud B.1, Otal P.2, Soulie M.1, Plante P.1, Joffre F.2 Hôpital Rangueil, Dept. of Urology and Andrology, Toulouse, France, 2Hôpital Rangueil, Dept. of Radiology, Toulouse, France, 3Chu Poitiers, Dept. of Pharmacy, Poitiers, France 1

Introduction & Objectives: To compare the results of selective embolization and surgery for symptomatic uncomplicated cases of renal angiomyolipoma (AML) in a medical and cost effectiveness evaluation. Material & Methods: A series of 35 patients (5 men and 30 women) were treated for symptomatic uncomplicated AML in our institution. Treatment consisted of surgery in 19 cases and embolization in 16 cases. Satisfaction and post-operative pain were assessed by questionnaire. MRI re-evaluation was done. Total cost was calculated (in Euro) by making the sum of direct technological cost (or treatment cost), direct medical cost (or human cost), and direct cost of treatment for the health structure. The criterion of effectiveness was the success of treatment defined as the absence of risk of hemorrhage. In a cost effectiveness analysis, treatments were compared using the incremental cost efficacy ratio (ICER). Results: Sixteen patients were entered in the embolization group and 19 in the surgery group. Groups were not different for mean age (45.2 vs. 47.6), the number of AML (1.6 vs. 1.7) and mean tumor size (55 vs. 44 mm). Embolization and surgery were effective in 86% and 100% of cases, respectively. Duration of procedure (p=0.03), blood loss (0.002), duration in intensive care unit (p=0.01) and total hospital stay (p=0.0009) were improved with embolization. Satisfaction scales also favoured embolization for physical (p=0.02), moral (p=0.01) as well as social (p=0.03) domains. Rates of complications, clearance of creatinine, and postoperative pain were not different. Overall, embolization was more cost effective than surgery (differential of 7756 E). Conclusions: Medical and economic analyses favour embolization in symptomatic renal AML or AML at risk of complication.

P21 RESEARCH AND MEDICAL TREATMENT OF UROLITHIASIS Thursday, 19 March, 09.15-10.45, Room C5



331

Stolzenburg J.U.1, Hellawell G.O.2, Do M.1, Haefner T.1, Dietel A.1, Liatsikos E.N.3 University of Leipzig, Dept. of Urology, Leipzig, Germany, 2Northwick Park Hospital, Dept. of Urology, London, United Kingdom, 3University of Patras, Dept. of Urology, Patras, Greece

1

Introduction & Objectives: The concept of scar-free surgery has been a longstanding goal that is close to being realised by laparoscopic endoscopic single site surgery (LESS). LESS is an evolving approach to laparoscopic surgery that has been made possible by the development of single port systems and novel, flexible instruments. We performed LESS for renal tumour nephrectomy in a series of four patients. Material & Methods: Four patients underwent single port nephrectomy using the R-Port (Advance Surgical Concepts), inserted via a transumbilical incision in all cases. A novel, flexible grasper (Real Hand) and a 5mm high definition camera (Olympus) were used in addition to standard laparoscopic equipment. Results: All operations were technically successful via the umbilical incision with no conversions to conventional laparoscopy. All were T1 renal tumours (1 right-sided and 3 left-sided, size 4 – 6 cm). The median patient age was 65 years and median BMI was 22.5. The median operative duration was 140 minutes (range 120 to 180 minutes) and the median blood loss was 100mls (range 50 150mls). Histology confirmed complete excision of specimen confined renal cell carcinoma. No intra- or post-operative complications occurred. Conclusions: We found that LESS is a feasible and safe approach in this select group of patients (low BMI and low stage tumour). LESS has been made possible by the development of the multiport and flexible laparoscopic instruments that ensure no oncological compromise occurs. Single site surgery presents the closest approximation to scar-free surgery and will play an important role in the future development of laparoscopic surgery.



332

Renal phosphate control as a reliable predictive factor for stone recurrence

Hyaluronan secretion as a cell defense mechanism during early calcium oxalate associated injury

Kim Y.J.1, Kwon W.A.1, Yun S.J.1, Kim Y.T.2, Lee S.C.1, Kim W.J.1

Gohel M.D.I.1, Yuen J.W.M.1, Poon N.W.1, Shum D.K.Y.2, Tam P.C.3, Au D.W.T.4

Chungbuk National University, Dept. of Urology, Cheongju, South Korea, Hanyang University, Dept. of Urology, Cheongju, South Korea

1 2

Introduction & Objectives: Recent studies have suggested a defect in phosphate balance as a significant underlying cause of calcium urolithiasis. This study assessed the influence of decreased renal phosphate reabsorption capacity on urinary metabolic abnormalities, as well as stone recurrence. Material & Methods: A database of patient history, and serum and urine chemistry was analyzed for 950 consecutive stone formers (SF) and 91 normal controls. The maximal reabsorption of phosphate by the glomerular filtration rate (TmP/GFR) was calculated, and the effect of TmP/GFR on stone metabolites and stone recurrence was determined. A value of TmP/GFR lower than 1.83 mg/dl was defined as a low TmP/GFR level. Of the SF, 266 (28.0%) patients who had been followed for more than 36 months (median 49, range 2-152) were included in the recurrence analysis. Results: TmP/GFR was significantly less in SF compared to normal controls, and was negatively correlated with urinary excretion of uric acid, calcium, and phosphate. Of SF, 13.1% (124/950) had a low TmP/GFR and a higher prevalence of hypercalciuria and hyperuricosuria than individuals with normal TmP/GFR. The multivariate Cox regression model including clinical (age, sex, stone episode, family history) and metabolic (low urine volume, hypercalciuria, hyperuricosuria, hyperoxaluria, hypocitraturia) risk factors revealed that the low TmP/GFR (HR=1.685, 95% CI=1.040-2.730, p = 0.034) was a strong predictor of stone recurrence in SF. Conclusions: This study demonstrated that the renal phosphate reabsorption capacity is significantly decreased in SF compared to normal controls, and that a low TmP/GFR is associated with hypercalciuria and hyperuricosuria. Furthermore, renal phosphate handling is an independent predictive determinant for recurrence in SF.

The Hong Kong Polytechnic University, Dept. of Health Technology & Informatics, Hong Kong, 2The University of Hong Kong, Dept. of Biochemistry, Hong Kong, 3The University of Hong Kong, Dept. of Surgery, Hong Kong, 4The City University of Hong Kong, Dept. of Biology & Chemistry, Hong Kong 1

Introduction & Objectives: Calcium oxalate (CaOx) crystal retention and hyaluronan (HA) secretion have been suggested in vitro and in vivo, but the exact roles of HA in nephrolithiasis remain unknown. In the present study, the subsequent events of spontaneous crystallization were investigated in a novel transwell culture model with human kidney-2 (HK-2) cells. The objective of the study is to develop a cell culture model whereby the interaction of forming crystallite particles in situ on the cell culture (rather than adding pre-formed crystals) can be investigated. Material & Methods: By shaking the cells with crystal-forming salts in artificial urine on the upper insert layer, supported by culture medium in the bottom feeding well, CaOx dihydrates (COD) were formed after 10 minutes, under hypercaluric and hyperoxaluric conditions. Apical crystal adhesion was observed immediately in the culture along with cell cytotoxic effects. The cell-bound crystals were internalized within 18 hours, which were shown to be enclosed in vacuoles, as observed by scanning and transmission electron microscopy. Results: These observations speculate the defense mechanisms of the cells at an early stage of stone development. In addition, significant amounts of HA were measured in the harvested media collected from both layers. Such HA secretion was found to be regulated by the pro-inflammatory HA synthase-3 (HAS-3) gene, whilst the HAS-1 and HAS-2 gene expressions remain undetectable. Conclusions: Conclusively, HK-2 cells are capable to endocytose the cellbound COD crystals, with subsequent secretion of HAS-3-specific HA molecule acting as a suggestive inflammatory marker for urolithiasis.

Eur Urol Suppl 2009;8(4):203