Surgical outcomes of gallbladder cancer: the OMEGA retrospective, multicentre, international cohort study.

Background: Gallbladder cancer (GBC) is rare but aggressive. The extent of surgical intervention for different GBC stages is non-uniform, ranging from cholecystectomy alone to extended resections including major hepatectomy, resection of adjacent organs and routine extrahepatic bile duct resection (EBDR). Robust evidence here is lacking, however, and survival benefit poorly defined. This study assesses factors associated with recurrence-free survival (RFS), overall survival (OS) and morbidity and mortality following GBC surgery in high income countries (HIC) and low and middle income countries (LMIC). Methods: The multicentre, retrospective Operative Management of Gallbladder Cancer (OMEGA) cohort study included all patients who underwent GBC resection across 133 centres between 1st January 2010 and 31st December 2020. Regression analyses assessed factors associated with OS, RFS and morbidity. Findings: On multivariable analysis of all 3676 patients, wedge resection and segment IVb/V resection failed to improve RFS (HR 1.04 [0.84-1.29], p = 0.711 and HR 1.18 [0.95-1.46], p = 0.13 respectively) or OS (HR 0.96 [0.79-1.17], p = 0.67 and HR 1.48 [1.16-1.88], p = 0.49 respectively), while major hepatectomy was associated with worse RFS (HR 1.33 [1.02-1.74], p = 0.037) and OS (HR 1.26 [1.03-1.53], p = 0.022). Furthermore, EBDR (OR 2.86 [2.3-3.52], p < 0.0010), resection of additional organs (OR 2.22 [1.62-3.02], p < 0.0010) and major hepatectomy (OR 3.81 [2.55-5.73], p < 0.0010) were all associated with increased morbidity and mortality. Compared to LMIC, patients in HIC were associated with poorer RFS (HR 1.18 [1.02-1.37], p = 0.031) but not OS (HR 1.05 [0.91-1.22], p = 0.48). Adjuvant and neoadjuvant treatments were infrequently used. Interpretation: In this large, multicentre analysis of GBC surgical outcomes, liver resection was not conclusively associated with improved survival, and extended resections were associated with greater morbidity and mortality without oncological benefit. Aggressive upfront resections do not benefit higher stage GBC, and international collaborations are needed to develop evidence-based neoadjuvant and adjuvant treatment strategies to minimise surgical morbidity and prioritise prognostic benefit. Funding: Cambridge Hepatopancreatobiliary Department Research Fund.

Bioengineering liver tissue by repopulation of decellularised scaffolds.

Liver transplantation is the only curative therapy for end stage liver disease, but is limited by the organ shortage, and is associated with the adverse consequences of immunosuppression. Repopulation of decellularised whole organ scaffolds with appropriate cells of recipient origin offers a theoretically attractive solution, allowing reliable and timely organ sourcing without the need for immunosuppression. Decellularisation methodologies vary widely but seek to address the conflicting objectives of removing the cellular component of tissues whilst keeping the 3D structure of the extra-cellular matrix intact, as well as retaining the instructive cell fate determining biochemicals contained therein. Liver scaffold recellularisation has progressed from small rodent in vitro studies to large animal in vivo perfusion models, using a wide range of cell types including primary cells, cell lines, foetal stem cells, and induced pluripotent stem cells. Within these models, a limited but measurable degree of physiologically significant hepatocyte function has been reported with demonstrable ammonia metabolism in vivo. Biliary repopulation and function have been restricted by challenges relating to the culture and propagations of cholangiocytes, though advances in organoid culture may help address this. Hepatic vasculature repopulation has enabled sustainable blood perfusion in vivo, but with cell types that would limit clinical applications, and which have not been shown to have the specific functions of liver sinusoidal endothelial cells. Minority cell groups such as Kupffer cells and stellate cells have not been repopulated. Bioengineering by repopulation of decellularised scaffolds has significantly progressed, but there remain significant experimental challenges to be addressed before therapeutic applications may be envisaged.

Heterogeneity of management practices surrounding operable gallbladder cancer - results of the OMEGA-S international HPB surgical survey.

BACKGROUND: Gallbladder cancer (GBC) is an aggressive, uncommon malignancy, with variation in operative approaches adopted across centres and few large-scale studies to guide practice. We aimed to identify the extent of heterogeneity in GBC internationally to better inform the need for future multicentre studies. METHODS: A 34-question online survey was disseminated to members of the European-African Hepatopancreatobiliary Association (EAHPBA), American Hepatopancreatobiliary Association (AHPBA) and Asia-Pacific Hepatopancreatobiliary Association (A-PHPBA) regarding practices around diagnostic workup, operative approach, utilization of neoadjuvant and adjuvant therapies and surveillance strategies. RESULTS: Two hundred and three surgeons responded from 51 countries. High liver resection volume units (>50 resections/year) organised HPB multidisciplinary team discussion of GBCs more commonly than those with low volumes (p < 0.0001). Management practices exhibited areas of heterogeneity, particularly around operative extent. Contrary to consensus guidelines, anatomical liver resections were favoured over non-anatomical resections for T3 tumours and above, lymphadenectomy extent was lower than recommended, and a minority of respondents still routinely excised the common bile duct or port sites. CONCLUSION: Our findings suggest some similarities in the management of GBC internationally, but also specific areas of practice which differed from published guidelines. Transcontinental collaborative studies on GBC are necessary to establish evidence-based practice to minimise variation and optimise outcomes.

Liver regeneration biology: Implications for liver tumour therapies.

The liver has remarkable regenerative potential, with the capacity to regenerate after 75% hepatectomy in humans and up to 90% hepatectomy in some rodent models, enabling it to meet the challenge of diverse injury types, including physical trauma, infection, inflammatory processes, direct toxicity, and immunological insults. Current understanding of liver regeneration is based largely on animal research, historically in large animals, and more recently in rodents and zebrafish, which provide powerful genetic manipulation experimental tools. Whilst immensely valuable, these models have limitations in extrapolation to the human situation. In vitro models have evolved from 2-dimensional culture to complex 3 dimensional organoids, but also have shortcomings in replicating the complex hepatic micro-anatomical and physiological milieu. The process of liver regeneration is only partially understood and characterized by layers of complexity. Liver regeneration is triggered and controlled by a multitude of mitogens acting in autocrine, paracrine, and endocrine ways, with much redundancy and cross-talk between biochemical pathways. The regenerative response is variable, involving both hypertrophy and true proliferative hyperplasia, which is itself variable, including both cellular phenotypic fidelity and cellular trans-differentiation, according to the type of injury. Complex interactions occur between parenchymal and non-parenchymal cells, and regeneration is affected by the status of the liver parenchyma, with differences between healthy and diseased liver. Finally, the process of termination of liver regeneration is even less well understood than its triggers. The complexity of liver regeneration biology combined with limited understanding has restricted specific clinical interventions to enhance liver regeneration. Moreover, manipulating the fundamental biochemical pathways involved would require cautious assessment, for fear of unintended consequences. Nevertheless, current knowledge provides guiding principles for strategies to optimise liver regeneration potential.

Colorectal liver metastases: Current management and future perspectives.

The liver is the commonest site of metastatic disease for patients with colorectal cancer, with at least 25% developing colorectal liver metastases (CRLM) during the course of their illness. The management of CRLM has evolved into a complex field requiring input from experienced members of a multi-disciplinary team involving radiology (cross sectional, nuclear medicine and interventional), Oncology, Liver surgery, Colorectal surgery, and Histopathology. Patient management is based on assessment of sophisticated clinical, radiological and biomarker information. Despite incomplete evidence in this very heterogeneous patient group, maximising resection of CRLM using all available techniques remains a key objective and provides the best chance of long-term survival and cure. To this end, liver resection is maximised by the use of downsizing chemotherapy, optimisation of liver remnant by portal vein embolization, associating liver partition and portal vein ligation for staged hepatectomy, and combining resection with ablation, in the context of improvements in the functional assessment of the future remnant liver. Liver resection may safely be carried out laparoscopically or open, and synchronously with, or before, colorectal surgery in selected patients. For unresectable patients, treatment options including systemic chemotherapy, targeted biological agents, intra-arterial infusion or bead delivered chemotherapy, tumour ablation, stereotactic radiotherapy, and selective internal radiotherapy contribute to improve survival and may convert initially unresectable patients to operability. Currently evolving areas include biomarker characterisation of tumours, the development of novel systemic agents targeting specific oncogenic pathways, and the potential re-emergence of radical surgical options such as liver transplantation.

Portal venous repopulation of decellularised rat liver scaffolds with syngeneic bone marrow stem cells.

Liver transplantation is the only life-saving treatment for end-stage liver failure but is limited by the organ shortage and consequences of immunosuppression. Repopulation of decellularised scaffolds with recipient cells provides a theoretical solution, allowing reliable and timely organ sourcing without the need for immunosuppression. Recellularisation of the vasculature of decellularised liver scaffolds was investigated as an essential prerequisite to the survival of other parenchymal components. Liver decellularisation was carried out by portal vein perfusion using a detergent-based solution. Decellularised scaffolds were placed in a sterile perfusion apparatus consisting of a sealed organ chamber, functioning at 37°C in normal atmospheric conditions. The scaffold was perfused via portal vein with culture medium. A total of 107 primary cultured bone marrow stem cells, selected by plastic adherence, were infused into the scaffold, after which repopulated scaffolds were perfused for up to 30 days. The cultured stem cells were assessed for key marker expression using fluorescence-activated cell sorting (FACS), and recellularised scaffolds were analysed by light, electron and immunofluorescence microscopy. Stem cells were engrafted in portal, sinusoidal and hepatic vein compartments, with cell alignment reminiscent of endothelium. Cell surface marker expression altered following engraftment, from haematopoietic to endothelial phenotype, and engrafted cells expressed sinusoidal endothelial endocytic receptors (mannose, Fc and stabilin receptors). These results represent one step towards complete recellularisation of the liver vasculature and progress towards the objective of generating transplantable neo-organs.

Five year experience of gallbladder polyp surveillance and cost effective analysis against new European consensus guidelines.

BACKGROUND: Gallbladder polyp (GBP) surveillance seeks to identify early neoplasms, but practice varies amongst surgical units. Recent European consensus guidelines have recommended an evidence-based GBP surveillance strategy. In a tertiary centre Hepato-Pancreato-Biliary unit we examine GBP surveillance, malignant yield, and assess cost-effectiveness of the new European consensus guidelines. METHODS: Respective data were collected from all patients with ultrasonography-detected GBPs between January 2008 and January 2013. RESULTS: 558 patients had GBPs detected on ultrasonography. Following initial ultrasonography, 304 (54.5%) had further ultrasonography surveillance of which 168 were in a formal GBP surveillance programme. Pre-malignant/malignant pathology yield was 1.97% with an annual detection rate of 12.0 cases per 1000 GBPs surveyed. Cost-effectiveness analysis of European consensus guidelines calculated annual savings of £209 163 per 1000 GBPs surveyed. Compliance with these guidelines would result in an additional 12.5% of patients under surveillance requiring cholecystectomy. CONCLUSION: GBP surveillance uptake was suboptimal at 32.8%. The incidence of pre-malignant/malignant lesions in GBPs emphasises the importance of surveillance for early detection and management with a view to avoiding the poor outcomes associated with more advanced gallbladder cancer. Adherence to the new European consensus guidelines would be clinically cost-effective with significant potential savings demonstrated in this study.

Development of a Prognostic Model That Predicts Survival After Pancreaticoduodenectomy for Ampullary Cancer.

OBJECTIVES: The aims of this study were to (i) identify independent predictors of survival after pancreaticoduodenectomy for ampullary cancer and (ii) develop a prognostic model of survival. METHODS: Data were analyzed retrospectively on 110 consecutive patients who underwent pancreaticoduodenectomy between 2002 and 2013. Subjects were categorized into 3 nodal subgroups as per the recently proposed nodal subclassification: N0 (node negative), N1 (1-2 metastatic nodes), or N2 (≥3 metastatic nodes). Clinicopathological features and overall survival were compared by Kaplan-Meier and Cox regression analyses. RESULTS: The overall 1-, 3-, and 5-year survival rates were 79.8%, 42.2%, and 34.9%, respectively. The overall 1-, 3-, and 5-year survival rates for the N0 group were 85.2%, 71.9%, and 67.4%, respectively. The 1-, 3-, 5-year survival rates for the N1 and N2 subgroups were 81.5%, 49.4%, and 49.4% and 75%, 19.2%, and 6.4%, respectively (log rank, P < 0.0001). After performing a multivariate Cox regression analysis, vascular invasion and lymph node ratio were the only independent predictors of survival. Hence, a prediction model of survival was constructed based on those 2 variables. CONCLUSIONS: Using data from a carefully selected cohort of patients, we created a pilot prognostic model of postresectional survival. The proposed model may help clinicians to guide treatments in the adjuvant setting.

Surgical management of hepato-pancreatic metastasis from renal cell carcinoma.

AIM: To investigate the outcomes of liver and pancreatic resections for renal cell carcinoma (RCC) metastatic disease. METHODS: This is a retrospective, single centre review of liver and/or pancreatic resections for RCC metastases between January 2003 and December 2015. Descriptive statistical analysis and survival analysis using the Kaplan-Meier estimation were performed. RESULTS: Thirteen patients had 7 pancreatic and 7 liver resections, with median follow-up 33 mo (range: 3-98). Postoperative complications were recorded in 5 cases, with no postoperative mortality. Three patients after hepatic and 5 after pancreatic resection developed recurrent disease. Median overall survival was 94 mo (range: 23-94) after liver and 98 mo (range: 3-98) after pancreatic resection. Disease-free survival was 10 mo (range 3-55) after liver and 28 mo (range 3-53) after pancreatic resection. CONCLUSION: Our study shows that despite the high incidence of recurrence, long term survival can be achieved with resection of hepatic and pancreatic RCC metastases in selected cases and should be considered as a management option in patients with oligometastatic disease.

Incidental non-benign gallbladder histopathology after cholecystectomy in an United Kingdom population: Need for routine histological analysis?

AIM: To analyse the range of histopathology detected in the largest published United Kingdom series of cholecystectomy specimens and to evaluate the rational for selective histopathological analysis. METHODS: Incidental gallbladder malignancy is rare in the United Kingdom with recent literature supporting selective histological assessment of gallbladders after routine cholecystectomy. All cholecystectomy gallbladder specimens examined by the histopathology department at our hospital during a five year period between March 2008 and March 2013 were retrospectively analysed. Further data was collected on all specimens demonstrating carcinoma, dysplasia and polypoid growths. RESULTS: The study included 4027 patients. The majority (97%) of specimens exhibited gallstone or cholecystitis related disease. Polyps were demonstrated in 44 (1.09%), the majority of which were cholesterol based (41/44). Dysplasia, ranging from low to multifocal high-grade was demonstrated in 55 (1.37%). Incidental primary gallbladder adenocarcinoma was detected in 6 specimens (0.15%, 5 female and 1 male), and a single gallbladder revealed carcinoma in situ (0.02%). This large single centre study demonstrated a full range of gallbladder disease from cholecystectomy specimens, including more than 1% neoplastic histology and two cases of macroscopically occult gallbladder malignancies. CONCLUSION: Routine histological evaluation of all elective and emergency cholecystectomies is justified in a United Kingdom population as selective analysis has potential to miss potentially curable life threatening pathology.

Successful surgical management of ruptured umbilical hernias in cirrhotic patients.

Acute umbilical hernia rupture in patients with hepatic cirrhosis and ascites is an unusual, but potentially life-threatening complication, with postoperative morbidity about 70% and mortality between 60%-80% after supportive care and 6%-20% after urgent surgical repair. Management options include primary surgical repair with or without concomitant portal venous system decompression for the control of the ascites. We present a retrospective analysis of our centre's experience over the last 6 years. Our cohort consisted of 11 consecutive patients (median age: 53 years, range: 36-63 years) with advanced hepatic cirrhosis and refractory ascites. Appropriate patient resuscitation and optimisation with intravenous fluids, prophylactic antibiotics and local measures was instituted. One failed attempt for conservative management was followed by a successful primary repair. In all cases, with one exception, a primary repair with non-absorbable Nylon, interrupted sutures, without mesh, was performed. The perioperative complication rate was 25% and the recurrence rate 8.3%. No mortality was recorded. Median length of hospital stay was 14 d (range: 4-31 d). Based on our experience, the management of ruptured umbilical hernias in patients with advanced hepatic cirrhosis and refractory ascites is feasible without the use of transjugular intrahepatic portosystemic shunt routinely in the preoperative period, provided that meticulous patient optimisation is performed.

Surgical intervention for mediastinal pancreatic pseudocysts. A case series and review of the literature.

CONTEXT: Development of mediastinal pancreatic pseudocysts is a rare complication of pancreatitis. There is currently no consensus on the optimal management of this condition, options for which include conservative management with somatostatin analogues, endoscopic drainage procedures and surgery. CASE REPORT: Here we present two patients with mediastinal pancreatic pseudocysts which were initially managed endoscopically. However, in both cases, this led to complications secondary to the endoscopic procedures, recurrence or non-resolution of symptoms, requiring surgical cystogastrostomy and/or cystojejunostomy. CONCLUSION: These cases suggest that surgery may be ultimately necessary for mediastinal pancreatic pseudocysts where endoscopic procedures might have a high likelihood of failure.

Salvage pancreaticoduodenectomy after complete response to chemoradiotherapy for a previously unresectable pancreatic adenosquamous carcinoma: a case report.

Pancreatic cancer is known for its typically late presentation and poor survival rates, with overall 5-year survival of less than 5%. The role of chemotherapy alone or with radiotherapy in the management of locally advanced tumors continues to be an area of debate.We report a case of locally advanced, pancreatic adenosquamous carcinoma that was initially deemed unresectable intraoperatively. Nonetheless, the tumor was resected after radiological response to gemcitabine-capecitabine chemoradiotherapy regimen similar to the Selective Chemoradiation in Advanced LOcalised Pancreatic cancer trial. Histological examination revealed complete pathological response with extensive fibrosis (ypT0 N0). On 12-month follow-up CT, a single liver lesion in the left lateral segment was identified and confirmed to be a metastasis with cytological diagnosis via EUS and FNA. The disease remained stable and confined to the solitary hepatic metastasis after further gemcitabine chemotherapy. Therefore, a further successful resection was performed.The 2 main strategies for the management of locally advanced unresectable pancreatic cancer are chemotherapy induction followed by consolidation chemoradiotherapy or chemotherapy alone, with conflicting published evidence. Evidence for the optimal management of the rare histological type of adenosquamous carcinoma is scant. We present a case of such tumor with a complete pathological response to chemoradiotherapy. The results of future studies in the area are eagerly awaited.

Negative predictive value of drain amylase concentration for development of pancreatic fistula after pancreaticoduodenectomy.

BACKGROUND: Post-operative pancreatic fistula (POPF) is the major source of morbidity following pancreaticoduodenectomy. A predictive indicator would be highly advantageous. One potential marker is drain amylase concentration (DAC). However, its predictive value has not been fully established. METHODS: 405 patients undergoing pancreaticoduodenectomy at our centre over a 10 year period were reviewed to determine the value of DAC as a predictive indicator for the development of POPF. RESULTS: POPF developed in 58 patients (14%). These patients suffered greater morbidity. Overall 30-day mortality was 1.5%. Male gender (OR: 5.1; p = 0.0082) and age > 70 (OR 2; p = 0.0372) were independent risk factors for POPF, whilst Type 2 diabetes (OR: 0.2321; p = 0.0090) and pancreatic ductal-adenocarcinoma (OR: 0.3721; p = 0.0039) decreased POPF risk. The DACs post-operatively were significantly higher in those developing POPF, but with significant overlap. ROC curves revealed optimal threshold values for differentiating POPF and non-POPF patients. A DAC°<°1400 U/ml on day 1 and <768 U/ml on day 2, although having a poor positive predictive value (32-44%), had a very strong negative predictive value (97-99%). CONCLUSION: Our data suggest that post-operative DAC below the determined optimal threshold values on day 1 and 2 following pancreaticoduodenectomy carries high negative predictive value for POPF development and identifies patients in whom early drain removal, and enhanced recovery may be considered, with simultaneous assessment of operative and clinical factors.

Colonic and anal metastases from pancreato-biliary malignancies.

Pancreato-biliary malignancies often present with locally advanced or metastatic disease. Surgery is the mainstay of treatment although less than 20% of tumours are suitable for resection at presentation. Common sites for metastases are liver, lungs, lymph nodes and peritoneal cavity. Metastatic disease carries poor prognosis, with median survival of less than 3 mo. We report two cases where metastases from pancreato-biliary cancers were identified in the colon and anal canal. In both cases specific immunohistochemical staining was utilised in the diagnosis. In the first case, the presenting complaint was obstructive jaundice due to an ampullary tumour for which a pancreato-duodenectomy was carried out. However, the patient re-presented 4 wk later with an atypical anal fissure which was found to be metastatic deposit from the primary ampullary adenocarcinoma. In the second case, the patient presented with obstructive jaundice due to a biliary stricture. Subsequent imaging revealed sigmoid thickening, which was confirmed to be a metastatic deposit. Distal colonic and anorectal metastases from pancreato-biliary cancers are rare and can masquerade as primary colorectal tumours. The key to the diagnosis is the specific immunohistochemical profile of the intestinal lesion biopsies.

Improved long-term survival after resection of colorectal liver metastases following staging with FDG positron emission tomography.

BACKGROUND AND OBJECTIVES: Actual long-term survival of patients with colorectal liver metastases staged by PET CT has not been reported. Objectives were to investigate whether PET CT staging results in actual improved long-term survival, to examine outcome in patients with 'equivocal' PET CT scans, and those excluded from hepatectomy by PET CT. METHODS: A retrospective analysis of patients undergoing hepatectomy for colorectal liver metastases between March 1998 and September 2008. RESULTS: Overall 5- and 10-year survival was 44.8% and 23.9%. PET CT staging resulted in management changes in 23% of patients. PET CT staged patients showed significantly better survival than those staged by CT alone at 3 years (79.8% vs. 54.1%) and at 5 years (54.1% vs. 37.3%) with median survivals of 6.4 years versus 3.9 years (log rank P = 0.018). Patients with equivocal PET CT scans showed worse median survival than those with favourable PET CT (log rank P = 0.002), but may include a subpopulation whose prognosis trends towards a more favourable outcome than those excluded from liver resection by PET CT, whose median survival remains limited to 21 months. CONCLUSIONS: Staging of patients with colorectal liver metastases by PET CT is associated with significantly improved actual long-term survival, and provides valuable prognostic information which guides surgical and oncological treatments.

Molecular pathogenesis of hepatic adenomas and its implications for surgical management.

INTRODUCTION: Hepatic adenomas (HAs) are benign tumors of the liver, which can be solitary or multiple, and have a definite risk of malignant degeneration. DISCUSSION: The pathogenesis and natural history of this disease entity were previously unknown. Recent research into the molecular pathogenesis of this condition has provided evidence for the malignant transformation of some of these adenomas. In the current article, we discuss the current evidence on the molecular biology underlying malignant transformation of hepatic adenomas and the implications for the surgical management of this disease.

Laparoscopic adrenalectomy: auditing the 10 year experience of a single centre.

BACKGROUND: Laparoscopic adrenalectomy (LA) is the gold standard for benign adrenal resection, and has been performed at our centre since 2000. We present a retrospective audit of our ten-year experience, and discuss the learning curve. METHODS: Creating a retrospective database, clinical and outcome data were collected for all resections performed over a ten-year period (2000-2010). Patients were chronologically divided into an 'early' (first 40 cases) and 'late' (subsequent cases) group to provide an insight into the learning curve. RESULTS: Over this period, 134 laparoscopic resections were performed, predominantly for benign adenomas (80.3%), with 48% of patients having primary hyperaldosteronism. There was almost equal sex distribution and mean age was 50.2 years, with a median BMI of 28.2. The mean operating time for left and right procedures were 127 and 124 min respectively, with 56.7% of resections being left sided. Our rate of conversion to open was 3.9%. Median length of stay was 4 days post-operatively. There was no mortality and 8.7% patients experienced a surgical complication. Analysis of the grouped data demonstrated a statistically significant reduction in open conversion rate (p = 0.017) and operative time (p = 0.011) in the 'late' group. Among the two groups there was no statistically significant difference in the length of stay and surgical complication rate. All results were comparable to published series in the literature. CONCLUSION: LA has proven to be a safe procedure with a low complication rate at our centre. Our data provide evidence that operative time and conversion rate improves with experience.

Direct histological processing of EUS biopsies enables rapid molecular biomarker analysis for interventional pancreatic cancer trials.

OBJECTIVE: Current practice to diagnose pancreatic cancer is accomplished by endoscopic ultrasound guided fine needle aspiration (EUS-FNA) using a cytological approach. This method is time consuming and often fails to provide suitable specimens for modern molecular analyses. Here, we compare the cytological approach with direct formalin fixation of pancreatic EUS-FNA micro-cores and evaluate the potential to perform molecular biomarker analysis on these specimen. METHODS: 130 specimens obtained by EUS-FNA with a 22G needle were processed by the standard cytological approach and compared to a separate cohort of 130 specimens that were immediately formalin fixed to preserve micro-cores of tissue prior to routine histological processing. RESULTS: We found that direct formalin fixation significantly shortened the time required for diagnosis from 3.6 days to 2.9 days (p<0.05) by reducing the average time (140 vs 33 min/case) and number of slides (9.65 vs 4.67 slides/case) for histopathological processing. Specificity and sensitivity yielded comparable results between the two approaches (82.3% vs 77% and 90.9% vs 100%). Importantly, EUS-FNA histology preserved the tumour tissue architecture with neoplastic glands embedded in stroma in 67.89% of diagnostic cases compared to 27.55% with the standard cytological approach (p < 0.001). Furthermore, micro-core samples were suitable for molecular studies including the immunohistochemical detection of intranuclear Hes1 in malignant cells, and the laser-capture microdissection-mediated measurement of Gli-1 mRNA in tumour stromal myofibroblasts. CONCLUSIONS: Direct formalin fixation of pancreatic EUS-FNA micro-cores demonstrates superiority regarding diagnostic delay, costs, and specimen suitability for molecular studies. We advocate this approach for future investigational trials in pancreatic cancer patients.