A self-healing multispectral transparent adhesive peptide glass.

Despite its disordered liquid-like structure, glass exhibits solid-like mechanical properties1. The formation of glassy material occurs by vitrification, preventing crystallization and promoting an amorphous structure2. Glass is fundamental in diverse fields of materials science, owing to its unique optical, chemical and mechanical properties as well as durability, versatility and environmental sustainability3. However, engineering a glassy material without compromising its properties is challenging4-6. Here we report the discovery of a supramolecular amorphous glass formed by the spontaneous self-organization of the short aromatic tripeptide YYY initiated by non-covalent cross-linking with structural water7,8. This system uniquely combines often contradictory sets of properties; it is highly rigid yet can undergo complete self-healing at room temperature. Moreover, the supramolecular glass is an extremely strong adhesive yet it is transparent in a wide spectral range from visible to mid-infrared. This exceptional set of characteristics is observed in a simple bioorganic peptide glass composed of natural amino acids, presenting a multi-functional material that could be highly advantageous for various applications in science and engineering.

Inhibitor-Mediated Structural Transition in a Minimal Amyloid Model.

Despite the fundamental clinical importance of amyloid fibril formation, its mechanism is still enigmatic. Crystallography of minimal amyloid models was a milestone in the understanding of the architecture and biological activities of amyloid fibers. However, the crystal structure of ultimate dipeptide-based amyloids is not yet reported. Herein, we present the crystal structure of a typical amyloid-forming minimal dipeptide, Ac-Phe-Phe-NH2 (Ac-FF-NH2 ), showing a canonical ß-sheet structure at the atomic level. The simplicity of the structure helped in investigating amyloid-inhibition using crystallography, never previously reported for larger peptide models. Interestingly, in the presence of an inhibitor, the supramolecular packing of Ac-FF-NH2 molecules rearranged into a supramolecular 2-fold helix (21 helix). This study promotes our understanding of the mechanism of amyloid formation and of the structural transitions that occur during the inhibition process in a most fundamental model.

Endoscopic Treatment for Large Multifocal Upper Tract Urothelial Carcinoma.

PURPOSE: We reviewed the oncologic and surgical outcomes of endoscopic treatments for low grade upper tract urothelial carcinoma, and assessed the prognostic significance of tumor size, location and multifocality. MATERIALS AND METHODS: We retrospectively reviewed all patients who underwent endoscopic treatment for low grade upper tract urothelial carcinoma at our institution between 2014 and 2019. Tumors were treated with a dual laser generator, which alternately produces holmium and neodymium lasers. A stringent ureteroscopic followup protocol was conducted. We looked for an association between outcome and tumor size, location or multifocality, and for predictive factors for time to local recurrence and progression. RESULTS: The cohort included 59 patients (62 renal units), 27% of tumors were multifocal and 40% were >2 cm. The median followup time was 22 months (IQR 11-41), and the median number of ureteroscopies was 5.5 (4-9). Local recurrence was observed in 46 renal units (74.1%) at a median of 6.5 months after initial surgery. Four patients (6.4%) developed disease progression and were referred for radical surgery: 2 had pathological progression and 2 had a rapid and high volume local recurrence, and 1 later developed metastatic disease. The progression-free rate was 93.2%. Tumor location in kidney (p=0.03, HR 1.95) and multifocality (p=0.005, HR 3.25) significantly predicted time to local recurrence. No factor predicted time to progression. CONCLUSIONS: Ureteroscopic treatment of large, multifocal, low grade upper tract urothelial carcinoma is feasible, does not involve significant complications and has good short-term oncologic outcomes, with a 93.2% progression-free survival rate. Tumors located in the kidney and multifocality yielded shorter time to local recurrence but not progression.

The urologist's learning curve of "in-bore" magnetic resonance-guided prostate biopsy.

BACKGROUND: The combination of multi-parametric MRI to locate and define suspected lesions together with their being targeted by an MRI-guided prostate biopsy has succeeded in increasing the detection rate of clinically significant disease and lowering the detection rate of non-significant prostate cancer. In this work we investigate the urologist's learning curve of in-bore MRI-guided prostate biopsy which is considered to be a superior biopsy technique. MATERIALS AND METHODS: Following Helsinki approval by The Chaim Sheba Medical Center ethics committee in accordance with The Sheba Medical Center institutional guidelines (5366-28-SMC) we retrospectively reviewed 110 IB-MRGpBs performed from 6/2016 to 1/2019 in a single tertiary center. All patients had a prostate multi-parametric MRI finding of at least 1 target lesion (prostate imaging reporting and data system [PI-RADS] score ≥ 3). We analyzed biopsy duration and clinically significant prostate cancer detection of targeted sampling in 2 groups of 55 patients each, once by a urologist highly trained in IB-MRGpBs and again by a urologist untrained in IB-MRGpBs. These two parameters were compared according to operating urologist and chronologic order. RESULTS: The patients' median age was 68 years (interquartile range 62-72). The mean prostate-specific antigen level and prostate size were 8.6 ± 9.1 ng/d and 53 ± 27 cc, respectively. The mean number of target lesions was 1.47 ± 0.6. Baseline parameters did not differ significantly between the 2 urologists' cohorts. Overall detection rates of clinically significant prostate cancer were 19%, 55%, and 69% for PI-RADS 3, 4 and 5, respectively. Clinically significant cancer detection rates did not differ significantly along the timeline or between the 2 urologists. The average duration of IB-MRGpB targeted sampling was 28 ± 15.8 min, correlating with the number of target lesions (p < 0.0001), and independent of the urologist's expertise. Eighteen cases defined the cutoff for the procedure duration learning curve (p < 0.05). CONCLUSIONS: Our data suggest a very short learning curve for IB-MRGpB-targeted sampling duration, and that clinically significant cancer detection rates are not influenced by the learning curve of this technique.

Oncologic Outcomes Following Robot-Assisted Radical Prostatectomy for Clinical T3 Prostate Disease.

BACKGROUND: Little is known about oncologic outcomes following robot-assisted-radical-prostatectomy (RALP) for clinical T3 (cT3) prostate cancer. OBJECTIVES: To investigate oncologic outcomes of patients with cT3 prostate cancer treated by RALP. METHODS: Medical records of patients who underwent RALP from 2010 to 2018 were retrieved. cT3 cases were reviewed. Demographic and pre/postoperative pathology data were analyzed. Patients were followed in 3-6 month intervals with repeat PSA analyses. Adjuvant/salvage treatments were monitored. Biochemical recurrence (BCR) meant PSA levels of ≥ 0.2 ng/ml. RESULTS: Seventy-nine patients met inclusion criteria. Median age at surgery was 64 years. Preoperative PSA level was 7.14 ng/dl, median prostate weight was 54 grams, and 23 cases (29.1%) were down-staged to pathological stage T2. Positive surgical margin rate was 42%. Five patients were lost to follow-up. Median follow-up time for the remaining 74 patients was 24 months. Postoperative relapse in PSA levels occurred in 31 patients (42%), and BCR in 28 (38%). Median time to BCR was 9 months. The overall 5-year BCR-free survival rate was 61%. Predicting factors for BCR were age (hazard-ratio [HR] 0.85, 95% confidence interval [95%CI] 0.74-0.97, P = 0.017) and prostate weight (HR 1.04, 95%CI 1.01-1.08, P = 0.021). Twenty-six patients (35%) received adjuvant/salvage treatments. Three patients died from metastatic prostate cancer 31, 52, and 78 months post-surgery. Another patient died 6 months post-surgery of unknown reasons. The 5-year cancer-specific survival rate was 92. CONCLUSIONS: RALP is an oncologic effective procedure for cT3 prostate cancer. Adjuvant/salvage treatment is needed to achieve optimal disease-control.

Modification of a Single Atom Affects the Physical Properties of Double Fluorinated Fmoc-Phe Derivatives.

Supramolecular hydrogels formed by the self-assembly of amino-acid based gelators are receiving increasing attention from the fields of biomedicine and material science. Self-assembled systems exhibit well-ordered functional architectures and unique physicochemical properties. However, the control over the kinetics and mechanical properties of the end-products remains puzzling. A minimal alteration of the chemical environment could cause a significant impact. In this context, we report the effects of modifying the position of a single atom on the properties and kinetics of the self-assembly process. A combination of experimental and computational methods, used to investigate double-fluorinated Fmoc-Phe derivatives, Fmoc-3,4F-Phe and Fmoc-3,5F-Phe, reveals the unique effects of modifying the position of a single fluorine on the self-assembly process, and the physical properties of the product. The presence of significant physical and morphological differences between the two derivatives was verified by molecular-dynamics simulations. Analysis of the spontaneous phase-transition of both building blocks, as well as crystal X-ray diffraction to determine the molecular structure of Fmoc-3,4F-Phe, are in good agreement with known changes in the Phe fluorination pattern and highlight the effect of a single atom position on the self-assembly process. These findings prove that fluorination is an effective strategy to influence supramolecular organization on the nanoscale. Moreover, we believe that a deep understanding of the self-assembly process may provide fundamental insights that will facilitate the development of optimal amino-acid-based low-molecular-weight hydrogelators for a wide range of applications.

[ROBOT ASSISTED PYELOPLASTY IN ADULTS WITH URETERO-PELVIC JUNCTION OBSTRUCTION (UPJO)].

BACKGROUND: Robotic-pyeloplasty (RP) for uretero-pelvic-junction-obstruction (UPJO) has been performed in our institution since 2013. OBJECTIVES: To summarize the outcomes of RP in adults over 18 years of age. METHODS: Adult RP cases have been prospectively documented. Analysis included demographic data such as age, sex, American Association of Anesthesiology-ASA Score, surgical-side, pre-operative imaging. Operative time (OT), estimated blood loss (EBL), length of stay (LOS) and short-term complications were also recorded. In all cases a JJ-stent has been left in place and subsequently taken out. Complications were classified in accordance with the Clavien-Dindo classification criteria. Patients were seen periodically with repeat imaging. The renal scan was performed at least once during the post-operative follow-up. Results are given as median (inter-quartile range) or numeric values (%). RESULTS: A total of 32 patients aged 33.5 years (21-45.2) had RP between the years 2013-2020, among which 53% were females and 59% right sided. An ASA score of 1-2 has been observed in 87.5% of all cases. Skin-to-skin OT was 163 min (136-185), and EBL was 5 ml (0-30). Short-term post-operative complications were hematuria (3.1%), urinary leak/urinoma (12.5%), body temperature>38.30C (12.5%). In 2 cases (6.2%) the JJ-stent had been re-positioned in the operating-theater (Clavien-Dindo 3b). LOS was 3 days (2-4) and JJ-stent had been taken out 39 days (31.7-45.2) post-operatively. Median length of follow-up was 19.5 months (9.5-26.7). In 92.3% of cases an improvement in hydronephrosis has been observed in post-operative imaging. The renal scan did not demonstrate renal function deterioration. CONCLUSIONS: Adult robotic pyeloplasty for UPJO is safe and effective. Low complication rates and over 90% success rates have been observed. These findings are in line with those found in previous studies.

[FACTORS PREDICTING FULL URINARY CONTINENCE FOLLOWING ROBOT-ASSISTED LAPAROSCOPIC RADICAL PROSTATECTOMY (RALP)].

BACKGROUND: Urinary Incontinence (UI) following Robot-Assisted Laparoscopic-Radical Prostatectomy (RALP) adversely affects patients' quality of life. OBJECTIVES: To find parameters that predict full urinary continence (FUC) following RALP. METHODS: Out of an established prospective RALP database, we retrieved and analyzed parameters that potentially predict FUC: age, Body Mass Index, American Anesthesiology Association (ASA) score, previous abdominal surgeries, pre-operative IPSS (International Prostate-Symptom Score), operative time (OT), estimated blood loss (EBL), peritoneum closure and prostate weight. FUC has been defined as 0 pads/day. Univariate analysis has been executed for comparison between patient groups, whereas multivariate analysis has been implemented for the detection of predicting factors for FUC. Data are presented as median (interquartile range) or numeric value (%). RESULTS: A total of 431 RALP cases were recorded between the years 2010-2019. Final analysis included 364 patients with full medical records; 81% gained FUC within 15 weeks (8-28); 96% gained FUC or used 1 pad/day within 17.5 weeks (8-36). Among those who gained FUC, smaller prostates (p=0.028) and low EBL (p=0.025) have been observed. On multivariate analysis EBL has been associated with UI (OR=0.9). CONCLUSIONS: Most patients gained FUC following RALP. EBL was found as risk factor for UI.

[CLINICAL OUTCOMES FOLLOWING ROBOT-ASSISTED PARTIAL NEPHRECTOMY (RAPN)].

BACKGROUND: Partial nephrectomy is the gold standard treatment for renal tumors less than 7 cm. OBJECTIVES: To describe surgical techniques and trends of treating renal tumors less than 7 cm at our department and present the clinical outcomes of our experience with Robot-Assisted Partial Nephrectomy (RAPN). METHODS: Out of an established prospective RAPN database, we retrieved demographic, clinical, surgical and pathological parameters. Operation length was defined as the time between the first surgical incision and the last suture (skin to skin). Warm ischemia time (WIT) was defined as the time between the renal artery clamping and clamp releasing. Data is presented as mean (range, standard deviation) or numeric value (%). RESULTS: Overall, 250 RAPN cases were recorded between the years 2013-2020. Mean tumor size was 32 mm. Mean operation length was 153 minutes. Mean warm ischemia time was 17.5 minutes. Intra-operative complication rates, including converting the surgery to an open approach or to radical nephrectomy, was low. Mean estimated blood loss was 359 cc. An increase in the utilization of the robotic approach has been recorded throughout the years, with a concurrent decrease in the open and laparoscopic approaches. CONCLUSIONS: RAPN is associated with lower complication rates and superior perioperative outcomes, therefore considered a good alternative to the open and laparoscopic approaches. Thus, RAPN is the gold standard treatment for renal tumors less than 7 cm at our institute.

[FOCAL TREATMENT OF PROSTATE CANCER - LEADING AND FUTURE TECHNIQUES, OUTCOMES AND COMPLICATIONS].

INTRODUCTION: Focal treatment for prostate cancer has been proposed as an innovative strategy that aims to achieve oncological benefit while reducing treatment-related morbidity. This treatment is suitable for patients with low and intermediate risk, organ-confined disease. Focal therapy can be categorized as follows: unifocal index lesion ablation, multifocal ablation, hemi-gland ablation or subtotal gland ablation. Different types of energies are applied in focal therapy including high intensity focal ultrasound (HIFU), cryotherapy, focal laser ablation (FLA), irreversible electroporation (IRE) and Photodynamic therapy (PDT). In this review we will briefly present a summary of leading techniques and the available data regarding their oncological outcomes and adverse events. Whole-gland therapies were excluded from this review.

[UPPER TRACT UROTHELIAL CARCINOMA].

INTRODUCTION: Upper tract urothelial carcinoma is a relatively rare malignancy, but with an increasing prevalence. The main risk factor for the disease is smoking. The most common presentation is hematuria or flank pain. Workup is made by imaging of the upper tract - CTU/MRU (Computed Tomography-Urography/Magnetic resonance (MR) urography) and diagnostic uretero-nephroscopy with biopsy. In the past several years there is major advancement in our understanding of the disease and how to treat it, mainly in nephron-sparing treatments. A risk-stratification is usually conducted according to parameters such as tumor size, distribution, and pathologic diagnosis. The low-risk group is usually offered nephron-sparing treatments such as segmental ureterectomy, endoscopic treatments, and lately - local chemotherapy. The high-risk group is usually offered radical resection of the kidney and ureter, with the possible addition of new-adjuvant and adjuvant treatments. In this article we will review the epidemiology, risk factors, diagnosis, and treatment of this malignancy, with a distinction between the risk groups.

Mechanical Enhancement and Kinetics Regulation of Fmoc-Diphenylalanine Hydrogels by Thioflavin†T.

The self-assembly of peptides is a key direction for fabrication of advanced materials. Novel approaches for fine tuning of macroscopic and microscopic properties of peptide self-assemblies are of a high demand for constructing biomaterials with desired properties. In this work, while studying the kinetics of the Fmoc-Diphenylalanine (Fmoc-FF) dipeptide self-assembly using the Thioflavin T (ThT) dye, we observed that the presence of ThT strongly modifies structural and mechanical properties of the Fmoc-FF hydrogel. Notably, the presence of ThT resulted in a tenfold increase of the gelation time and in the formation of short and dense fibers in the hydrogel. As a result of these morphological alteration higher thermal stability, and most important, tenfold increase of the hydrogel rigidity was achieved. Hence, ThT not only slowed the kinetics of the Fmoc-FF hydrogel formation, but also strongly enhanced its mechanical properties. In this study, we provide a detailed description of the ThT effect on the hydrogel properties and suggest the mechanisms for this phenomenon, paving the way for the novel approach to the control of the peptide hydrogels' micro- and macroscale properties.

Management of Pancreatic Injuries Following Nephrectomy.

BACKGROUND: Pancreatic injuries during nephrectomy are rare, despite the relatively close anatomic relation between the kidneys and the pancreas. The data regarding the incidence and outcome of pancreatic injuries are scarce. OBJECTIVES: To assess the frequency and the clinical significance of pancreatic injuries during nephrectomy. METHODS: A retrospective analysis was conducted of all patients who underwent nephrectomy over a period of 30 years (1987-2016) in a large tertiary medical center. Demographic, clinical, and surgical data were collected and analyzed. RESULTS: A total of 1674 patients underwent nephrectomy during the study period. Of those, 553 (33%) and 294 patients (17.5%) underwent left nephrectomy and radical left nephrectomy, respectively. Among those, four patients (0.2% of the total group, 0.7% of the left nephrectomy group, and 1.36% of the radical left nephrectomy) experienced iatrogenic injuries to the pancreas. None of the injuries were recognized intraoperatively. All patients were treated with drains in an attempt to control the pancreatic leak and one patient required additional surgical interventions. Average length of stay was 65 days (range 15-190 days). Mean follow-up was 23.3 months (range 7.7-115 months). CONCLUSIONS: Pancreatic injuries during nephrectomy are rare and carry a significant risk for postoperative morbidity.

[THE EFFICACY OF ENDOSCOPIC DUAL LASER TREATMENT FOR LOW GRADE UPPER TRACT UROTHELIAL CARCINOMA].

INTRODUCTION: Until recently, radical nephroureterectomy was considered the gold standard treatment for upper tract urothelial carcinoma (UTUC). Post-operative complications, long-term adverse effects of nephrectomy as well as the risk of contralateral recurrence have led to the development of nephron-sparing techniques. OBJECTIVES: To evaluate the safety, complication rate, and oncologic outcomes of ureteroscopic nephron-sparing treatment for low-grade UTUC utilizing a hybrid laser system that incorporates two types of lasers: Nd:YAG and Ho:YAG. METHODS: We reviewed the files of patients who underwent ureteroscopic treatment for UTUC with the hybrid laser system between the years 2014-2018. Only cases of low-grade UTUC and follow-up time of at least 6 months were included in the present study. The following were analyzed: demographic data, tumor histologic characteristics, peri-operative complications, histologic upgrade, oncologic outcomes (i.e: local recurrence, local spread, metastatic progression). RESULTS: A total of 38 patients, who underwent 74 ureteroscopies, met inclusion criteria. Mean tumor size was 16.2 mm. No intra-operative complications were recorded. Two post-operative complications were recorded in one patient - hematuria and retroperitoneal bleeding - both had been treated conservatively. Mean follow-up time was 21.8 months. Local recurrence rate was 73%. Histologic upgrade has been observed in two patients. Four patients (10.5%) were referred to radical nephroureterectomy. There were no cases of local spread, distant metastases or death during the follow-up period. DISCUSSION: Endoscopic dual-laser treatment for low-grade UTUC is safe, surgically feasible and associated with good short-term oncologic outcome. Patient selection and strict follow-up are mandatory.

Co-Assembly between Fmoc Diphenylalanine and Diphenylalanine within a 3D Fibrous Viscous Network Confers Atypical Curvature and Branching.

Supramolecular polymer co-assembly is a useful approach to modulate peptide nanostructures. However, the co-assembly scenario where one of the peptide building blocks simultaneously forms a hydrogel is yet to be studied. Herein, we investigate the co-assembly formation of diphenylalanine (FF), and Fmoc-diphenylalanine (FmocFF) within the 3D network of FmocFF hydrogel. The overlapping peptide sequence between the two building blocks leads to their co-assembly within the gel state modulating the nature of the FF crystals. We observe the formation of branched microcrystalline aggregates with an atypical curvature, in contrast to the FF assemblies obtained from aqueous solution. Optical microscopy reveal the sigmoidal kinetic growth profile of these aggregates. Microfluidics and ToF-SIMS experiments exhibit the presence of co-assembled structures of FF and FmocFF in the crystalline aggregates. Molecular dynamics simulation was used to decipher the mechanism of co-assembly formation.

Oligosaccharides Self-Assemble and Show Intrinsic Optical Properties.

Self-assembling peptides and oligonucleotides have given rise to synthetic materials with several applications in nanotechnology. Aggregation of synthetic oligosaccharides into well-defined architectures has not been reported even though natural polysaccharides, such as cellulose and chitin, are key structural components of biomaterials. Here, we report that six synthetic oligosaccharides, ranging from dimers to hexamers, self-assemble into nanostructures of varying morphologies and emit within the visible spectrum in an excitation-dependent manner. Well-defined differences in chain length, monomer modification, and aggregation methods yield glycomaterials with distinct shapes and properties. The excitation-dependent fluorescence in a broad range within the visible spectrum illustrates their potential for use in optical devices and imaging applications. We anticipate that our systematic approach of studying well-defined synthetic oligosaccharides will form the foundation of our understanding of carbohydrate interactions in nature.

Transition of Metastable Cross-α Crystals into Cross-ß Fibrils by ß-Turn Flipping.

The ensemble of native, folded state was once considered to represent the global energy minimum of a given protein sequence. More recently, the discovery of the cross-ß amyloid state revealed that deeper energy minima exist, often associated with pathogenic, fibrillar deposits, when the concentration of proteins reaches a critical value. Fortunately, a sizable energy barrier impedes the conversion from native to pathogenic states. However, little is known about the structure of the related transition state. In addition, there are indications of polymorphism in the amyloidogenic process. Here, we report the first evidence of the conversion of metastable cross-α-helical crystals to thermodynamically stable cross-ß-sheet-like fibrils by a de novo designed heptapeptide. Furthermore, for the first time, we demonstrate at atomic resolution that the flip of a peptide plane from a type I to a type II' turn facilitates transformation to cross-ß structure and assembly of a dry steric zipper. This study establishes the potential of a peptide turn, a common protein secondary structure, to serve as a principal gatekeeper between a native metastable folded state and the amyloid state.

Microfluidics for real-time direct monitoring of self- and co-assembly biomolecular processes.

Molecular self-assembly is a major approach for the fabrication of functional supramolecular nanomaterials. This dynamic, straightforward, bottom-up procedure may result in the formation of various architectures at the nano-scale, with remarkable physical and chemical characteristics. Biological and bio-inspired building blocks are especially attractive due to their intrinsic tendency to assemble into well-organized structures, as well as their inherent biocompatibility. To further expand the morphological diversity, co-assembly methods have been developed, allowing to produce alternative unique architectures, enhanced properties, and improved structural control. However, in many cases, mechanistic understanding of the self- and co-assembly processes is still lacking. Microfluidic techniques offer a set of exclusive tools for real-time monitoring of biomolecular self-organization, which is crucial for the study of such dynamic processes. Assembled nuclei, confined by micron-scale pillars, could be subjected to controlled environments aiming to assess the effect of different conditions on the assembly process. Other microfluidics setups can produce droplets at a rate of over 100 s-1, with volumes as small as several picoliters. Under these conditions, each droplet can serve as an individual pico/nano-reactor allowing nucleation and assembly. These processes can be monitored, analyzed and imaged, by various techniques including simple bright-field microscopy. Elucidating the mechanism of such molecular events may serve as a conceptual stepping-stone for the rational control of the resulting physicochemical properties.

Intrinsic Fluorescence of Metabolite Amyloids Allows Label-Free Monitoring of Their Formation and Dynamics in Live Cells.

The formation of apoptosis-inducing amyloidal structures by metabolites has significantly extended the "amyloid hypothesis" to include non-proteinaceous, single metabolite building blocks. However, detection of metabolite assemblies is restricted compared to their larger protein-based counterparts owing to the hindrance of external labelling and limited immunohistochemical detection tools. Herein, we present the detection of the formation, dynamics, and cellular distribution of metabolite amyloid-like structures and provide mechanistic insights into the generation of supramolecular chromophores. Moreover, the intrinsic fluorescence properties allow the detection of metabolite assemblies in living cells without the use of external dyes. Altogether, this intrinsic fluorescence of metabolite assemblies further verifies their amyloidal nature, while providing an important tool for further investigation of their pathological role in inborn error of metabolism disorders.

Positive surgical margin following radical nephrectomy is an independent predictor of local recurrence and disease-specific survival.

BACKGROUND: Positive surgical margins (PSM) are recognized as an adverse prognostic sign and are often associated with higher rates of local and systemic disease recurrence. The data regarding the oncological outcome for PSM following radical nephrectomy (RN) is limited. We examined the predictive factors for PSM and its influence on survival and site of recurrence in patients treated with RN for renal cell carcinoma (RCC). METHODS: Clinical, pathologic and follow-up data on 714 patients undergoing RN for kidney cancer were analyzed. Secondary analysis included 44 patients with metastatic RCC upon diagnosis who underwent cytoreductive nephrectomy (CRN). Univariate and multivariable logistic regression models were fit to determine clinicopathologic features associated with PSM. A Cox proportional-hazards regression model was used to test the independent effects of clinical and pathologic variables on survival. RESULTS: PSM was documented in 17 cases (2.4%). PSM were associated with tumour size, advanced pathologic stage (pT3 vs. ≤ pT2) and presence of necrosis. On multivariate analysis, cancer-specific survival (CSS) was associated with tumour stage, size, presence of necrosis and PSM. PSM was also associated with local recurrence but not distant metastasis or overall survival (OS). CSS and OS were comparable between the PSM and metastatic RCC groups, but significantly lower than the negative margin group. CONCLUSIONS: The prevalence of PSM following RN is rare. Pathological data, including advanced stage (> pT2), tumour necrosis and tumour size, are associated with the presence of PSM. PSM is associated with tumour recurrence and CSS. Patients with PSM are a potential group for adjuvant therapy or for more careful and thorough follow-up following surgery.