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Background A distinct serum metabonomic pattern has been previously revealed to be associated with various forms of liver disease. Here, we aimed to apply mass spectrometry to obtain serum metabolomic profiles from individuals with cholangiocarcinoma and benign hepatobiliary diseases to gain an insight into pathogenesis and search for potential early-disease biomarkers. Methods Serum samples were profiled using a hydrophilic interaction liquid chromatography platform, coupled to a mass spectrometer. A total of 47 serum specimens from 8 cholangiocarcinoma cases, 20 healthy controls, 8 benign disease controls (bile duct strictures) and 11 patients with hepatocellular carcinoma (as malignant disease controls) were included. Data analysis was performed using univariate and multivariate statistics. Results The serum metabolome disparities between the metabolite profiles from healthy controls and patients with hepatobiliary disease were predominantly related to changes in lipid and lipid-derived compounds (phospholipids, bile acids and steroids) and amino acid metabolites (phenylalanine). A metabolic pattern indicative of inflammatory response due to cirrhosis and cholestasis was associated with the disease groups. The abundance of phospholipid metabolites was altered in individuals with liver disease, particularly cholangiocarcinoma, but no significant difference was seen between profiles from patients with benign biliary strictures and cholangiocarcinoma. Conclusion The serum metabolome in cholangiocarcinoma exhibited changes in metabolites related to inflammation, altered energy production and phospholipid metabolism. This study serves to highlight future avenues for biomarker research in large-scale studies.

Background: In 2017, an estimated 540 women in Sub-Saharan Africa died every day from preventable causes related to pregnancy and childbirth. To stem this public-health crisis, the WHO recommends a maternal and neonatal health continuity of patient care, yet most women do not meet this recommendation. Surveys suggest that illiteracy limits uptake of the proposed maternal-newborn package, yet little is known about the association between illiteracy and healthcare seeking, particularly in rural regions of low-income countries. This knowledge gap compromises the ability of public health experts and healthcare providers to provide culturally relevant policy and practice. To begin to address this gap this study explores the experiences related to care-seeking by illiterate, pregnant women in rural Tanzania.Methods: A qualitative study was conducted in four communities encompassing eight focus group discussions with 81 illiterate women, 13 interviews with illiterate women of reproductive age and seven interviews with members of these communities perceived to have some influence on women’s decisions concerning perinatal care services. Themes were coded and their relative importance determined using frequency reports and cross-tabulations. Findings: Three key themes emerged, illiterate women (1) could not read their healthcare cards or public health messaging; (2) spoke the local language, not Swahili, the language used by healthcare providers, and (3) have endeavored to develop coping strategies to overcome these obstacles. In addition, health service providers are often unaware of who is illiterate.Recommendations: More health needs of this group could be met, in the short term, by developing a protocol for health service providers to determine who is illiterate, providing translation services for those unable to speak Swahili, and graphic public health messaging that does not require literacy. In the long term, this barrier may be addressed by ensuring that all Tanzanians receive a high-quality, formal education, supporting community health workers, and recruiting healthcare providers from rural areas. A failure of to address the needs of this at-risk group will likely mean that they will continue to experience barriers to achieving the recommended continuity of patient care with detrimental health outcomes for both mothers and newborns.

BACKGROUND Liver volume (LV) can be non-invasively determined from the analysis of computed tomography (CT) images, and in patients with acute liver injury (ALI) or failure (ALF), it can reflect the balance of structural collapse with hepatic regeneration. We examined its relation to cause of liver injury, measures of liver function and histopathological findings, and utility in prediction of complications and mortality. METHODS Two hundred and seventy-three patients with ALF/ALI admitted to a specialist intensive care unit were studied. One hundred and ninety-nine patients (73%) had non-acetaminophen (NA) aetiologies and 74 (27%) had acetaminophen-induced disease. LV and proportion of predicted LV (PLV%) were determined from admission CT imaging. RESULTS LV and PLV% showed marked variation when aetiologic groups were compared (P

Background and aims Understanding of the significant genetic risk factors for Cholangiocarcinoma (CC) remains limited. Polymorphisms in the natural killer cell receptor G2D (NKG2D) gene have been shown to increase risk of CC transformation in patients with Primary Sclerosing Cholangitis (PSC). We present a validation study of NKG2D polymorphisms in CC patients without PSC. Methods Seven common Single Nucleotide Polymorphisms (SNPs) of the NKG2D gene were genotyped in 164 non-PSC related CC subjects and 257 controls with HaploView. The two SNPs that were positively identified in the previous Scandinavian study, rs11053781 and rs2617167, were included. Results The seven genotyped SNPs were not associated with risk of CC. Furthermore, haplotype analysis revealed that there was no evidence to suggest that any haplotype differs in frequency between cases and controls (P > 0.1). Conclusion The common genetic variation in NKG2D does not correlate significantly with sporadic CC risk. This is in contrast to the previous positive findings in the Scandinavian study with PSC-patients. The failure to reproduce the association may reflect an important difference between the pathogenesis of sporadic CC and that of PSC-related CC. Given that genetic susceptibility is likely to be multifaceted and complex, further validation studies that include both sporadic and PSC-related CC are required.

Cholangiocarcinoma is a fatal cancer of the biliary epithelium and has an incidence that is increasing worldwide. Survival beyond a year of diagnosis is less than 5%, and therapeutic options are few. Known risk factors include biliary diseases such as primary sclerosing cholangitis and parasitic infestation of the biliary tree, but most cases are not associated with any of these underlying diseases. Numerous in vitro and in vivo models, as well as novel analytical techniques for human samples, are helping to delineate the many pathways implicated in this disease, albeit at a frustratingly slow pace. As yet, however, none of these studies has been translated into improved patient outcome and, overall, the pathophysiology of cholangiocarcinoma is still poorly understood. There remains an urgent need for new approaches and models to improve management of this insidious and devastating disease. In this review, we take a bedside-to-bench approach to discussing cholangiocarcinoma and outline research opportunities for the future in this field.

Background Discriminatory metabolic profiles have been described in urinary 1 H nuclear magnetic resonance (NMR) spectroscopy studies of African patients with hepatocellular carcinoma (HCC). This study aimed to assess similarities in a UK cohort, where there is a greater etiological diversity. Methods Urine from cirrhosis and HCC patients was analyzed using a 600MHz 1 H NMR system. Multivariate analysis and median group MR spectra comparison identified metabolite alterations between groups. Metabolite identification was achieved through literature reference and statistical total correlation spectroscopy. Diagnostic accuracy was compared to serum alpha-fetoprotein (AFP). Results Of the 52 patients recruited, 13 samples from HCC and 25 from cirrhosis patients were selected. At 200IUmL −1 , diagnostic sensitivity of AFP was 27%. Multivariate analysis of urinary spectra generated diagnostic models with a sensitivity/specificity of 53.6%/96%. p-Cresol sulfate ( P =0.04), creatinine ( P =0.03), citrate ( P =0.21) and hippurate ( P =0.52) were reduced in the HCC patients. Carnitine ( P =0.31) and formate ( P =0.44) were elevated. Conclusion Diagnostic sensitivity was lower than previous African studies, but still outperformed serum AFP. Reduced creatinine, citrate and hippurate and elevated carnitine are comparable with the African studies. p-Cresol sulfate alteration is a novel finding and may indicate an altered sulfonation capacity of the liver in patients with HCC.

Accurate differentiation between benign and malignant causes of biliary obstruction remains challenging and reliable biomarkers are urgently needed. Bile is a potential source of such biomarkers. Our aim was to apply a proteomic approach to identify a potential biomarker in bile that differentiates between malignant and benign disease, and to assess its diagnostic accuracy. Neutrophil gelatinase-associated lipocalin (NGAL) is multi-functional protein, released from activated neutrophils, with roles in inflammation, immune function, and carcinogenesis. It has not previously been described in bile.Bile, urine, and serum were collected prospectively from 38 patients undergoing endoscopic retrograde cholangiopancreatography ("discovery" cohort); 22 had benign and 16 had malignant pancreatobiliary disease. Initially, label-free proteomics and immunoblotting were performed in samples from a subset of these patients. Enzyme-linked immunosorbent assay was then performed for NGAL as a potential biomarker on all samples in this cohort. The diagnostic performance of biliary NGAL was then validated in a second, independent group ("validation" cohort) of 21 patients with pancreatobiliary disease (benign n=14, malignant n=7).NGAL levels were significantly raised in bile from the malignant disease group, compared with bile from the benign disease group in the discovery cohort (median 1,556 vs. 480 ng/ml, P=0.007). Biliary NGAL levels had a receiver operating characteristic area under curve of 0.76, sensitivity 94%, specificity 55%, positive predictive value 60%, and negative predictive value 92% for distinguishing malignant from benign causes. Biliary NGAL was independent of serum biochemistry and carbohydrate antigen 19-9 (CA 19-9) in differentiating between underlying benign and malignant disease. No significant differences in serum and urine NGAL levels were found between benign and malignant disease. Combining biliary NGAL and serum CA 19-9 improved diagnostic accuracy for malignancy (sensitivity 85%, specificity 82%, positive predictive value 79%, and negative predictive value 87%). The diagnostic accuracy of biliary NGAL was confirmed in the second independent validation cohort.NGAL in bile is a novel potential biomarker to help distinguish benign from malignant biliary obstruction.

Background The currently available tumour markers used in the management of patients with colorectal metastases are of limited value. Tumour M2-pyruvate kinase (TuM2-PK), a tumour-associated isoenzyme of pyruvate kinase, is elevated in patients with gastrointestinal cancer. This study has measured TuIVI2-PK levels in patients before and after resection of colorectal liver metastases (CLM).Materials and methods Fifty patients with CLM and no local residual disease had TuM2-PK levels measured before liver resection. In 20 patients, TuM2-PK levels were repeated at 2 weeks, 5 weeks and 5 months after resection. Plasma levels were analysed by enzyme-linked immunosorbent assay (ScheBo, Giessen, Germany). Carcinoembryonic antigen (CEA) and CA19-9 levels were measured at the same time periods by electrochemiluminescence immunoassay. CEA, CA19-9 and TuM2-PK levels were compared with the tumour number, volume, differentiation and stage. Cut-off values used for TuM2-PK, CEA and CA19-9 were 15 IU/ml, 10 ng/ml and 391 U/ml, respectively.Results TuM2-PK was elevated in 68%, CEA in 62% and CA19-9 in 40% of patients with CLM. TuM2-PK+CEA was elevated in 88% and TuM2-PK + CA19-9 in 78% of patients. A significant correlation was observed between tumour volume and CEA (r= 0.34, P< 0.05) and CA19-9 (r= 0.49, P

Summary Background Chronic biochemical cholestasis has been shown to be associated with a fivefold increase in histologically advanced liver disease in patients receiving home parenteral nutrition. Aims To investigate prevalence of chronic biochemical cholestasis in home parenteral nutrition patients and examine factors influencing its occurrence. Methods Records of all patients receiving home parenteral nutrition for >6 months treated at a single centre were reviewed and plasma biochemistry recorded. Logistic regression analysis was employed to identify factors associated with prevalence of chronic biochemical cholestasis. Results Records of 113 patients were reviewed. The point prevalence of chronic biochemical cholestasis was 24%, increasing to 28% if patients receiving parenteral fluid and electrolytes only were excluded. In multivariate analysis, presence of colon in continuity was associated with a significantly lower prevalence of chronic biochemical cholestasis, while total parenteral calorie intake was associated with a higher prevalence of chronic biochemical cholestasis. No association was seen between small intestinal lengths or between parenteral lipid intake and chronic biochemical cholestasis in multivariate analysis. Conclusions Chronic biochemical cholestasis is common in patients receiving home parenteral nutrition. High parenteral calorie intake and lack of a colon in continuity with small intestine are independently associated with an increased risk of chronic biochemical cholestasis.

Introduction Sporadic cholangiocarcinoma (CC) occurs in subjects with no known risk factor for the disease. Its pathogenesis is likely to involve complex interaction of environmental and human factors, including genetic variation. Polymorphisms in natural killer cell receptor protein G2D (NKG2D) have been associated CC in subjects with primary sclerosing cholangitis (PSC). In a recent study, comparing 49 subjects with CC to 316 subjects with PSC and no CC, two single nucleotide polymorphisms (SNPs) in NKG2D were associated with an increased risk of CC: rs11053781 (OR 2.08, p value 0.011) and rs2617167 (OR 2.32, p value 0.0020). We aimed to test whether variation in NKG2D also modifies susceptibility to sporadic CC. Methods DNA was collected from 172 subjects with sporadic CC and a matched control cohort of 256. Haploview v 4.2 was used to select SNPs capturing common genetic variation around the NKG2D gene (MAF >0.05, pair-wise comparisons). This identified 7 SNPs to be genotyped, including rs11053781 and rs2617167. Genotyping was performed with a PCR based, robotic system. Hardy–Weinberg equilibrium testing, Armitage trend testing and haplotype frequency comparisons were undertaken. Correction for multiple testing was performed using a permutation method. Results All genotypes were in Hardy–Weinberg equilibrium. None of the individual SNPs were significantly associated with altered susceptibility to CC. Haplotype analysis revealed that no haplotypes significantly modified risk of CC. Conclusion This is the first study to examine NKG2D polymorphisms in sporadic CC. The study was well powered. We found no relationship between variation in NKG2D and susceptibility to CC, in contrast to prior findings in PSC patients with CC. This finding may reflect an important difference between the pathogenesis of sporadic CC and that of PSC related CC. It might point to a false-positive result in the prior study of PSC related CC, but it was well executed and produced strong, positive results. This could be elucidated in an additional candidate-gene validation study. However, with increasing availability and affordability, a genome wide association study (GWAS) may prove a more efficient method for further exploring genetic factors in cholangiocarcinoma.

Introduction MicroRNAs (miRNAs) are short, non-coding RNAs with a key role in post-transcriptional regulation, and regulate multiple pathways of tumorogenesis. Expression profiling of malignant cell lines, fresh and formalin-fixed tumour have identified potential miRNA signatures for pancreatic ductal adenocarcinoma (PDAC), and RNA deep sequencing has demonstrated that miRNAs can be quantified from bile, in bilary tract cancers 1 . Here, we report the first study of biliary miRNAs in PDAC. Methods 3 target miRNAs known to be overexpressed in PDAC were selected. Bile was collected at endoscopic retrograde cholangiopancreatography (ERCP) from patients with PDAC (n = 10) or gallstones (n = 8; used as a benign control). Bile was prepared as described1 and total RNA isolated using TRIzol (Invitrogen, Paisley, UK). Quantitative real-time reverse-transcription polymerase chain reaction (RT-qPCR) was performed using Taqman mature miRNA primers and probes (Applied Biosystems, Cheshire, UK). Expression of oncomiR-21, miR-155 and miR-106a was measured. Cycle passing threshold (Ct) was recorded and normalised to RNU6B expression. Relative expression was calculated as 2Ct_miRNA-Ct_RNU6B. PCR reactions were carried out in duplicate. Results miR-106a and oncomiR-21 were both highly expressed in the bile of patients with PDAC, compared to those with gallstones. miR-155 was not significantly upregulated in PDAC bile. Using miR-106a (cut-off level > 8.02), we discriminated PDAC from benign disease with a sensitivity and specificity of 80% [95% CI 44–98] and 100% [95% CI 63–100], respectively with an area under the curve (AUC) value of 0.88. OncomiR-21 was also upregulated in bile, but was not as reliable in discriminating diagnosis. Conclusion This study demonstrates that bile miRNAs are well-suited analytes for the development of sensitive and specific tests in PDAC. Although tumour breach of the biliary epithelium was not always suspected in our cohort from clinical investigations, malignancy-specific miRNAs were found intraluminally. Of the 3 miRNAs tested, ROC analysis identified miR-106a as the best potential PDAC biomarker, with reliable diagnostic specificity and sensitivity. However, further study may also identify miRNAs that also discriminate prognoses and response to therapy, guiding individualised treatment. Disclosure of Interest None Declared Reference Shigehara K, Yokomuro S, Ishibashi O, et al. Real-time PCR-based analysis of the human bile microRNAome identifies miR-9 as a potential diagnostic biomarker for biliary tract cancer. PloS one. 2011; 6(8):e23584.

Introduction Cholangiocarcinoma (CCA) is a primary biliary ductal cancer which is often difficult to diagnose and which carries a poor prognosis. New diagnostic tests are urgently needed to improve patient outcome. Bile is a rich source of potential novel biomarkers for CCA, due to its intimate proximity to the malignant lesion. However, there are no biliary biomarkers for CCA currently available. MicroRNAs (miRNAs) are key post-transcriptional regulators, and influence tumorogenesis. Studies on cell lines and tissue have identified several potential miRNA signatures for CCA, and recently miR-9 was identified as elevated in bile from CCA compared with benign disease 1 . In this study we aimed to measure specific miRNA expression in bile from patients with CCA, gallstone disease and pancreatic adenocarcinoma (PA) and to assess their performance in differentiating these causes of biliary obstruction. Methods Bile was collected at endoscopic retrograde cholangiopancreatography (ERCP) from patients with CCA (n = 6), PA (n = 10) and gallstones (n = 8; benign control). Bile was prepared as previously described1 and total RNA was isolated using TRIzol (Invitrogen, Paisley, UK). Quantitative real-time reverse-transcription polymerase chain reaction (RT-qPCR) was performed using Taqman mature miRNA primers and probes (Applied Biosystems, Cheshire, UK). Expression of oncomiR-21, miR-155 and miR-106a was measured. Cycle passing threshold (Ct) was recorded and normalised to RNU6B expression. Relative expression was calculated as 2Ct_miRNA-Ct_RNU6B. PCR reactions were carried out in duplicate. Results MiR-106a and oncomiR-21 were highly expressed in bile from patients with CCA compared to those with gallstones. MiR-155 was not significantly upregulated in malignancy. In discriminating CCA from benign disease, miR-106a had sensitivity and specificity of 83.3% [95% CI 36–100] and 88% [95% CI 47–100] respectively, with an AUC of 0.83 (cut-off level > 6.05). OncomiR-21 was also upregulated in the bile of both tumour types, but was not as reliable. Neither miRNA discriminated significantly between PA and CCA. Conclusion MiRNA can be reliably isolated from bile pellets. Both miR-106a and oncomiR-21 are potential novel biliary biomarkers for CCA, and could improve differentiation of benign from malignant disease at ERCP. Further work is required to validate these findings in a larger cohort and against other disease groups, and to investigate possible correlations between miRNA profile and disease course. Disclosure of Interest None Declared Reference Shigehara K, Yokomuro S, Ishibashi O, et al. Real-time PCR-based analysis of the human bile microRNAome identifies miR-9 as a potential diagnostic biomarker for biliary tract cancer. PloS one . 2011; 6(8):e23584.

Introduction Cholangiocarcinoma (CC) is a malignant neoplasm of the bile duct. Diagnosis of CC is hampered by the inadequate performance of current plasma markers of disease, particularly in patients with preexisting primary sclerosing cholangitis (PSC). We aimed to identify potential new protein biomarkers of CC Methods In an initial discovery study, blood plasma samples from 18 subjects with CC, 17 with PSC and 10 healthy controls were subjected to SELDI-TOF MS. Comparisons of m/z peak intensity were made between groups using the Mann-Whitney U test. Differentiating m/z peaks were then confirmed in a further validation study of 81 subjects with CC, 54 with PSC and 90 healthy controls. Pearson´s correlation was used to investigate the relationship of each m/z peak´s intensity to routine laboratory indices. Diagnostic performance was investigated using receiver operator characteristic area-under-the curve (ROC-AUC) analyses. Multiple linear regression was used to investigate the performance of combinations of differentiating m/z peaks, as well as the combination of m/z peaks with routine laboratory markers (including CA19–9). Results Seven differentially expressed m/z peaks were identified in the CC group and these were subsequently confirmed in the validation study (p = 2.6 × 10–4 to 9.4 × 10–13). The intensity of the seven m/z peaks of interest did not correlate with creatinine, ALP, bilirubin, CRP, white cell count or CA19–9. A panel of three peaks discriminated CC from PSC subjects with ROC-AUC of 0.76 (sensitivity 75%, specificity 64%). A panel of five peaks discriminated CC subjects from healthy controls with ROC-AUC of 0.90 (sensitivity 95%, specificity 74%). Addition of routine laboratory indices did not change the diagnostic performance of these models significantly. Conclusion SELDI-TOF has been used to successfully identify seven m/z peaks that are differentially intense in CC subjects (total n = 99), when compared to PSC subjects (n = 64) and healthy controls (n = 107). These peaks appear to be independent of standard markers of renal impairment, cholestasis, sepsis and inflammation, as well as CA19–9. Individually, and more so in combination, these peaks exceed the expected diagnostic performance of CA19–9, particularly in discriminating CC from PSC. Work to identify the proteins represented by these m/z peaks is ongoing. Disclosure of Interest None Declared

Introduction Better biomarkers are urgently needed to assist accurate diagnosis and appropriate treatment of malignant biliary obstruction, as, although malignancy is a common cause of obstructive jaundice, current diagnostic techniques often fail to differentiate benign from malignant disease. Molecular analysis of bile has recently produced promising candidate biomarkers. Previous work from our group found that biliary neutrophil gelatinase-associated lipocalin (NGAL), a small extracellular 25-kDa protein with several biological functions, differentiates obstructive jaundice from malignancy from that in benign disease. The mechanism of NGAL in hepatopancreatobiliary (HPB) malignancy is unknown, although in other systems it promotes neoplastic diffusion by complexing and stabilising matrix metalloproteinase-9 (MMP9), enabling local invasion. Aims (1) To investigate possible biliary complexing of MMP9 and NGAL as a mechanism of tumorigenesis. (2) To validate our previous findings of biliary NGAL as a novel biomarker of malignancy in biliary obstruction. Methods Bile samples were collected from 77 patients undergoing ERCP (n=77, 22 with malignant disease and 55 with benign disease) at Imperial College London. ELISA was used to quantify levels of MMP9/NGAL complexes and of NGAL and MMP9 occurring independently in bile. Pearson9s correlation analysis was used to determine the relationship between NGAL, MMP9 and NGAL/MMP9 complex levels, and statistical significance assessed by the Mann–Whitney U test. Results Biliary NGAL levels were significantly higher in malignant biliary obstruction compared to benign disease (median 1555 ng/ml vs 402 ng/ml, p=0.003), giving a ROC AUC of 0.74. Biliary MMP9 and NGAL/MMP9 complex levels were not different between these groups (p=0.527, p=0.760). Unbound biliary NGAL and MMP9 levels correlated poorly (r 2 =0.03, p>0.05). Unbound NGAL correlated poorly with complex (r 2 =0.07, p>0.05) whereas unbound MMP9 correlated with NGAL/MMP9 complex level (r 2 =0.73, p Conclusion This study is novel in confirming the presence of MMP9 in bile, alone and in complex with NGAL. However, although NGAL was increased in malignancy, MMP9 and MMP9/NGAL complex were not, suggesting that NGAL acts independently of MMP9 in endobiliary HPB malignancy. Mechanisms remain to be elucidated. This study also supports previous reports of NGAL as a novel and independent bile biomarker of malignant biliary obstruction. Competing interests None declared.

Introduction We have previously demonstrated that the level of neutrophil gelatinase-associated lipocalin (NGAL) is increased in the bile of patients with pancreatobiliary malignancy. NGAL is expressed by activated neutrophils and many other cell types and is thought to have bacteriostatic, pro-proliferative and pro-metastatic functions. NGAL can be detected in the blood plasma. We hypothesised that the plasma NGAL level is elevated in patients with cholangiocarcinoma (CC) compared with patients with primary sclerosing cholangitis (PSC), and with healthy volunteers. Methods Plasma samples were collected from 97 patients with confirmed CC, 62 patients with PSC and no CC and 82 healthy controls. Plasma NGAL quantification was performed in duplicate on plasma from each subject using a Quantikine ELISA kit (R&D Systems, Minneapolis, Minnesota, USA). CC and healthy control cohorts were compared using the Student t test and receiver operator characteristic (ROC) analysis. Differences between CC and PSC cohorts were then sought. Pearson9s correlation analysis was used to assess relationships between the levels of NGAL and other plasma markers. Results Median NGAL concentrations (range) in CC, PSC and healthy controls were 92 ng/ml (14–644), 83 (43–171) and 64 (29–132) respectively. NGAL levels were significantly higher in plasma from CC patients compared with healthy controls (p 2 =0.14), white cell count (r 2 =0.09), bilirubin (r 2 =0.01), ALP (r 2 =0.02) or creatinine (r 2 =0.03). There was moderate correlation between NGAL and Ca19-9 concentrations (r 2 =0.38). Conclusion NGAL is expressed at significantly higher concentrations in the plasma of patients with CC compared to plasma from healthy controls and from subjects with PSC. This finding appears to be independent of renal impairment, cholestasis or systemic inflammatory response, suggesting that NGAL may represent a novel plasma biomarker of CC. Competing interests None declared.

Introduction Obstruction of the biliary tree has a variety of aetiologies. The correct diagnosis is crucial for appropriate definitive therapy. A major differential diagnosis of biliary obstruction is pancreatic adenocarcinoma (PA). PA is the 10th most common cancer in the UK with mortality similar to incidence. Diagnosis of PA relies on a combination of cross-sectional imaging and serum biomarkers, but only a minority of cases are diagnosed correctly and early enough for curative resection. Earlier diagnostic certainty would be likely to improve outcome and guide therapeutic strategy. Proteomic profiling is a promising technique for new biomarker discovery, but has rarely been successfully carried out in human bile. This project (1) analyses and compares the proteomes of bile from PA patients vs. bile from patients with benign biliary disease and (2) seeks to identify potential protein biomarkers that can differentiate PA from benign biliary disease. Methods Bile was aspirated at ERCP from patients with benign or malignant biliary obstruction. Particulate matter was removed by centrifugation and equal volumes subjected to SDS-PAGE. In-gel trypsin digestion was performed and the resulting peptides analysed by tandem mass spectrometry. Proteins were identified using SEQUEST to search the human RefSeq protein sequence database. Progenesis software was used to compare relative levels of proteins between patient groups. Results Proteomic analysis of bile from four patients with PA and four with benign biliary obstruction was performed. Over 100 different proteins were identified, including pancreatic gastric triacylglycerol lipase, carboxypeptidase B and bile salt-activated lipase, confirming that the profile of proteins represents the biliary proteome. Several differentially expressed proteins were identified including upregulation of carcinoembryonic antigen–related cell adhesion molecule 6 (CEACAM6) in the malignant group. Conclusion This work confirms that bile is amenable to proteomic analysis and that differences in the biliary proteome can be detected in malignant and non-malignant cases. We confirmed earlier reports of CEACAM6 overexpression in PA. We are currently analysing the data further to identify additional candidate biomarker proteins. Future work will extend this approach to the study of bile in other diseases, such as cholangiocarcinoma.