Volatile organic compounds in bile can diagnose malignant biliary strictures in the setting of pancreatic cancer: a preliminary observation

Identification of breath volatile organic compounds to distinguish pancreatic adenocarcinoma, pancreatic cystic neoplasm, and patients without pancreatic lesions

BACKGROUND

Volatile organic compounds (VOCs) are a promising potential biomarker that may be able to identify the presence of cancers.

AIM

To identify exhaled breath VOCs that distinguish pancreatic ductal adenocarcinoma (PDAC) from intraductal papillary mucinous neoplasm (IPMN) and healthy volunteers.

METHODS

We collected exhaled breath from histologically proven PDAC patients, radiological diagnosis IPMN, and healthy volunteers using the ReCIVA® device between 10/2021-11/2022. VOCs were identified by thermal desorption-gas chromatography/field-asymmetric ion mobility spectrometry and compared between groups.

RESULTS

A total of 156 participants (44% male, mean age 62.6 ± 10.6) were enrolled (54 PDAC, 42 IPMN, and 60 controls). Among the nine VOCs identified, two VOCs that showed differences between groups were dimethyl sulfide [0.73 vs 0.74 vs 0.94 arbitrary units (AU), respectively; P = 0.008] and acetone dimers (3.95 vs 4.49 vs 5.19 AU, respectively; P < 0.001). After adjusting for the imbalance parameters, PDAC showed higher dimethyl sulfide levels than the control and IPMN groups, with adjusted odds ratio (aOR) of 6.98 (95%CI: 1.15-42.17) and 4.56 (1.03-20.20), respectively (P < 0.05 both). Acetone dimer levels were also higher in PDAC compared to controls and IPMN (aOR: 5.12 (1.80-14.57) and aOR: 3.35 (1.47-7.63), respectively (P < 0.05 both). Acetone dimer, but not dimethyl sulfide, performed better than CA19-9 in PDAC diagnosis (AUROC 0.910 vs 0.796). The AUROC of acetone dimer increased to 0.936 when combined with CA19-9, which was better than CA19-9 alone (P < 0.05).

CONCLUSION

Dimethyl sulfide and acetone dimer are VOCs that potentially distinguish PDAC from IPMN and healthy participants. Additional prospective studies are required to validate these findings.

Identification of urinary volatile organic compounds as a potential non-invasive biomarker for esophageal cancer

Early diagnosis of esophageal cancer (EC) is extremely challenging. The study presented herein aimed to assess whether urinary volatile organic compounds (VOCs) may be emerging diagnostic biomarkers for EC. Urine samples were collected from EC patients and healthy controls (HCs). Gas chromatography-ion mobility spectrometry (GC-IMS) was next utilised for volatile organic compound detection and predictive models were constructed using machine learning algorithms. ROC curve analysis indicated that an 8-VOCs based machine learning model could aid the diagnosis of EC, with the Random Forests having a maximum AUC of 0.874 and sensitivities and specificities of 84.2% and 90.6%, respectively. Urine VOC analysis aids in the diagnosis of EC.

Primary Sclerosing Cholangitis-Associated Cholangiocarcinoma: From Pathogenesis to Diagnostic and Surveillance Strategies

Cholangiocarcinoma (CCA) is the most common malignancy in patients with primary sclerosing cholangitis (PSC), accounting for 2-8% of cases and being the leading cause of death in these patients. The majority of PSC-associated CCAs (PSC-CCA) develop within the first few years after PSC diagnosis. Older age and male sex, as well as concomitant inflammatory bowel disease (IBD) or high-grade biliary stenosis, are some of the most relevant risk factors. A complex combination of molecular mechanisms involving inflammatory pathways, direct cytopathic damage, and epigenetic and genetic alterations are involved in cholangiocytes carcinogenesis. The insidious clinical presentation makes early detection difficult, and the integration of biochemical, radiological, and histological features does not always lead to a definitive diagnosis of PSC-CCA. Surveillance is mandatory, but current guideline strategies failed to improve early detection and consequently a higher patient survival rate. MicroRNAs (miRNAs), gene methylation, proteomic and metabolomic profile, and extracellular vesicle components are some of the novel biomarkers recently applied in PSC-CCA detection with promising results. The integration of these new molecular approaches in PSC diagnosis and monitoring could contribute to new diagnostic and surveillance strategies.

Identification and validation of volatile organic compounds in bile for differential diagnosis of perihilar cholangiocarcinoma

Early and differential diagnosis of perihilar cholangiocarcinoma (PHCCA) is highly challenging. This study aimed to evaluate whether volatile organic compounds (VOCs) in bile samples could be emerging diagnostic biomarkers for PHCCA. We collected 200 bile samples from patients with PHCCA and benign biliary diseases (BBD), including a 140-patient training cohort and an 60-patient test cohort. Gas chromatography-ion mobility spectrometry (GC-IMS) was used for VOCs detection. The predictive models were constructed using machine learning algorithms. Our analysis detected 19 VOC substances using GC-IMS in the bile samples and resulted in the identification of three new VOCs, 2-methoxyfuran, propyl isovalerate, and diethyl malonate that were found in bile. Unsupervised hierarchical clustering analysis supported that VOCs detected in the bile could distinguish PHCCA from BBD. Twelve VOCs defined according to 32 signal peaks had significant statistical significance between BBD and PHCCA, including four up-regulated VOCs in PHCCA, such as 2-ethyl-1-hexanol, propyl isovalerate, cyclohexanone, and acetophenone, while the rest eight VOCs were down-regulated. ROC curve analysis revealed that machine learning models based on VOCs could help diagnosing PHCCA. Among them, SVM provided the highest AUC of 0·966, with a sensitivity and specificity of 93·1% and 100%, respectively. The diagnostic model based on different VOC spectra could be a feasible method for the differential diagnosis of PHCCA.

Diagnosis Biomarkers of Cholangiocarcinoma in Human Bile: An Evidence-Based Study

Simple Summary

A liquid biopsy has the characteristics of low trauma and easy acquisition in the diagnosis of cholangiocarcinoma. Many researchers try to find diagnostic or prognostic biomarkers of CCA through blood, urine, bile and other body fluids. Due to the close proximity of bile to the lesion and the stable nature, bile gradually comes into people’s view. The evaluation of human bile diagnostic biomarkers is not only to the benefit of screening more suitable clinical markers but also of exploring the pathological changes of the disease.

Abstract

Cholangiocarcinoma (CCA) is a multifactorial malignant tumor of the biliary tract, and the incidence of CCA is increasing in recent years. At present, the diagnosis of CCA mainly depends on imaging and invasive examination, with limited specificity and sensitivity and late detection. The early diagnosis of CCA always faces the dilemma of lacking specific diagnostic biomarkers. Non-invasive methods to assess the degree of CAA have been developed throughout the last decades. Among the many specimens looking for CCA biomarkers, bile has gotten a lot of attention lately. This paper mainly summarizes the recent developments in the current research on the diagnostic biomarkers for CCA in human bile at the levels of the gene, protein, metabolite, extracellular vesicles and volatile organic compounds.

Diagnostic Ability of Volatile Organic Compounds in Digestive Cancer: A Systematic Review With Meta-Analysis

Background:

Volatile organic compounds (VOCs) have been involved in cancer diagnosis via breath, urine, and feces. We aimed to assess the diagnostic ability of VOCs on digestive cancers.

Methods:

We systematically reviewed prospective clinical trials evaluating VOCs’ diagnostic ability on esophageal, gastric, colorectal, hepatic, and pancreatic cancer (PC). Databases including PubMed and Ovid-Medline were searched.

Results:

A total of 35 trials with 5314 patient-times qualified for inclusion. The pooled sensitivity of VOCs diagnosing gastroesophageal cancer from healthy controls is 0.89 (95% confidence interval [CI]: 0.82-0.94), the pooled specificity is 0.890 (95% CI: 0.84-0.93), and area under the curve (AUC) of the summary receiver operating characteristic curve is 0.95 (95% CI: 0.93-0.95). The pooled sensitivity of VOCs diagnosing colorectal cancer from heathy controls is 0.92 (95% CI: 0.85-0.96), the pooled specificity is 0.88 (95% CI: 0.77-0.94), and the AUC is 0.96 (95% CI: 0.94-0.97). The pooled sensitivity of VOCs distinguishing gastrointestinal (GI) cancer from precancerous lesions is 0.84 (95% CI: 0.67-0.92), the pooled specificity is 0.74 (95% CI: 0.43-0.91), and the AUC is 0.87 (95% CI: 0.84-0.89). The pooled sensitivity of VOCs diagnosing hepatocellular carcinoma is 0.68 (95% CI: 0.52-0.81), the pooled specificity is 0.81 (95% CI: 0.47-0.96), and the AUC is 0.78 (95% CI: 0.74-0.81). The pooled sensitivity of VOCs diagnosing PC is 0.88 (95% CI: 0.80-0.93), the pooled specificity is 0.82 (95% CI: 0.62-0.93), and the AUC is 0.92 (95% CI: 0.89-0.94).

Conclusions:

Volatile organic compounds have potential role in diagnosing GI cancer with comparatively high sensitivity, specificity, and AUC (PROSPERO registration number: CRD42021260039).

Hyphenated Mass Spectrometry versus Real-Time Mass Spectrometry Techniques for the Detection of Volatile Compounds from the Human Body

Mass spectrometry (MS) is an analytical technique that can be used for various applications in a number of scientific areas including environmental, security, forensic science, space exploration, agri-food, and numerous others. MS is also continuing to offer new insights into the proteomic and metabolomic fields. MS techniques are frequently used for the analysis of volatile compounds (VCs). The detection of VCs from human samples has the potential to aid in the diagnosis of diseases, in monitoring drug metabolites, and in providing insight into metabolic processes. The broad usage of MS has resulted in numerous variations of the technique being developed over the years, which can be divided into hyphenated and real-time MS techniques. Hyphenated chromatographic techniques coupled with MS offer unparalleled qualitative analysis and high accuracy and sensitivity, even when analysing complex matrices (breath, urine, stool, etc.). However, these benefits are traded for a significantly longer analysis time and a greater need for sample preparation and method development. On the other hand, real-time MS techniques offer highly sensitive quantitative data. Additionally, real-time techniques can provide results in a matter of minutes or even seconds, without altering the sample in any way. However, real-time MS can only offer tentative qualitative data and suffers from molecular weight overlap in complex matrices. This review compares hyphenated and real-time MS methods and provides examples of applications for each technique for the detection of VCs from humans.

Volatile organic compounds in bile can distinguish pancreatic cancer from chronic pancreatitis: a prospective observational study

BACKGROUND

Early and accurate diagnosis of pancreatic cancer is important. Our aim was to identify potential volatile organic compounds (VOCs) in the bile that can help distinguish pancreatic cancer from chronic pancreatitis.

METHODS

In this prospective observational study, bile was aspirated from patients undergoing endoscopic retrograde cholangiopancreatography for chronic pancreatitis and pancreatic cancer, and the gaseous headspace was analyzed using mass spectrometry.

RESULTS

The study included a discovery cohort of 57 patients (46 pancreatic cancer, 11 chronic pancreatitis) and a validation cohort of 31 patients (19 and 12, respectively). Using logistic regression analysis, the model [0.158 × age + 9.747 × log (ammonia) - 3.994 × log (acetonitrile) + 5.044 × log (trimethylamine) - 30.23] successfully identified patients with pancreatic cancer with a sensitivity of 93.5 % and specificity of 100 % (likelihood ratio 40.9, area under the curve 0.98, 95 % confidence interval 0.95 - 1.00). The diagnostic accuracy of this model was confirmed in the second independent validation cohort.

CONCLUSION

The measurement of VOCs in bile helped to accurately distinguish pancreatic cancer from chronic pancreatitis.

Prospect of in vitro Bile Fluids Collection in Improving Cell-Based Assay of Liver Function

The liver plays a pivotal role in the clearance of drugs. Reliable assays for liver function are crucial for various metabolism investigation, including toxicity, disease, and pre-clinical testing for drug development. Bile is an aqueous secretion of a functioning liver. Analyses of bile are used to explain drug clearance and related effects and are thus important for toxicology and pharmacokinetic research. Bile fluids collection is extensively performed in vivo, whereas this process is rarely reproduced as in the in vitro studies. The key to success is the technology involved, which needs to satisfy multiple criteria. To ensure the accuracy of subsequent chemical analyses, certain amounts of bile are needed. Additionally, non-invasive and continuous collections are preferable in view of cell culture. In this review, we summarize recent progress and limitations in the field. We highlight attempts to develop advanced liver cultures for bile fluids collection, including methods to stimulate the secretion of bile in vitro. With these strategies, researchers have used a variety of cell sources, extracellular matrix proteins, and growth factors to investigate different cell-culture environments, including three-dimensional spheroids, cocultures, and microfluidic devices. Effective combinations of expertise and technology have the potential to overcome these obstacles to achieve reliable in vitro bile assay systems.

Non-enzymatic hydrogen sulfide production from cysteine in blood is catalyzed by iron and vitamin B6

Hydrogen sulfide (H2S) plays important roles in metabolism and health. Its enzymatic generation from sulfur-containing amino acids (SAAs) is well characterized. However, the existence of non-enzymatic H2S production from SAAs, the chemical mechanism, and its biological implications remain unclear. Here we present non-enzymatic H2S production in vitro and in blood via a reaction specific for the SAA cysteine serving as substrate and requires coordinated catalysis by Vitamin B6, pyridoxal(phosphate), and iron under physiological conditions. An initial cysteine-aldimine is formed by nucleophilic attack of the cysteine amino group to the pyridoxal(phosphate) aldehyde group. Free or heme-bound iron drives the formation of a cysteine-quinonoid, thiol group elimination, and hydrolysis of the desulfurated aldimine back to pyridoxal(phosphate). The reaction ultimately produces pyruvate, NH3, and H2S. This work highlights enzymatic production is inducible and robust in select tissues, whereas iron-catalyzed production contributes underappreciated basal H2S systemically with pathophysiological implications in hemolytic, iron overload, and hemorrhagic disorders.

Current situation and problems in diagnosis and treatment of sphincter of Oddi dysfunction

Sphincter of Oddi dysfunction (SOD) is a clinical syndrome referring to the loss of normal physiological function of the sphincter of Oddi with upper abdominal pain from the gallbladder and pancreas, postprandial abdominal bloating, elevation of liver or pancreatic enzymes, common bile duct dilation, pancreatitis and so on. SOD is more common in patients after cholecystectomy. Although the established criteria for diagnosing and treating SOD have been applied in clinical practice, its diagnosis and treatment have long been a controversial topic since the best diagnostic and treatment methods are still unconfirmed, partly because of its natural course, disease treatment process, and long-term follow-up outcomes that have not been determined in large controlled studies. This article briefly reviews the latest research of SOD and comprehensively analyzes the current status and existing problems in the diagnosis and treatment of SOD, with an aim to provide appropriate advice for clinicians to diagnose and treat this disease.

Fiber-Optic Bio-sniffer (Biochemical Gas Sensor) Using Reverse Reaction of Alcohol Dehydrogenase for Exhaled Acetaldehyde

Volatile organic compounds (VOCs) exhaled in breath have huge potential as indicators of diseases and metabolisms. Application of breath analysis for disease screening and metabolism assessment is expected since breath samples can be noninvasively collected and measured. In this research, a highly sensitive and selective biochemical gas sensor (bio-sniffer) for gaseous acetaldehyde (AcH) was developed. In the AcH bio-sniffer, a reverse reaction of alcohol dehydrogenase (ADH) was employed for reducing AcH to ethanol and simultaneously consuming a coenzyme, reduced form of nicotinamide adenine dinucleotide (NADH). The concentration of AcH can be quantified by fluorescence detection of NADH that was consumed by reverse reaction of ADH. The AcH bio-sniffer was composed of an ultraviolet light-emitting diode (UV-LED) as an excitation light source, a photomultiplier tube (PMT) as a fluorescence detector, and an optical fiber probe, and these three components were connected with a bifurcated optical fiber. A gas-sensing region of the fiber probe was developed with a flow-cell and an ADH-immobilized membrane. In the experiment, after optimization of the enzyme reaction conditions, the selectivity and dynamic range of the AcH bio-sniffer were investigated. The AcH bio-sniffer showed a short measurement time (within 2 min) and a broad dynamic range for determination of gaseous AcH, 0.02-10 ppm, which encompassed a typical AcH concentration in exhaled breath (1.2-6.0 ppm). Also, the AcH bio-sniffer exhibited a high selectivity to gaseous AcH based on the specificity of ADH. The sensor outputs were observed only from AcH-contained standard gaseous samples. Finally, the AcH bio-sniffer was applied to measure the concentration of AcH in exhaled breath from healthy subjects after ingestion of alcohol. As a result, a significant difference of AcH concentration between subjects with different aldehyde dehydrogenase type 2 (ALDH2) phenotypes was observed. The AcH bio-sniffer can be used for breath measurement, and further, an application of breath analysis-based disease screening or metabolism assessment can be expected due to the versatility of its detection principle, which allows it to measure other VOCs by using NADH-dependent dehydrogenases.

A highly sensitive liquid chromatography electrospray ionization mass spectrometry method for quantification of TMA, TMAO and creatinine in mouse urine

Our method describes the quantification in mouse urine of trimethylamine (TMA), trimethylamine N-oxide (TMAO) and creatinine. The method combines derivatization of TMA, with ethyl bromoacetate, and LC chromatographic separation on an ACE C₁₈ column. The effluent was continuously electrosprayed into the linear ion trap mass spectrometer (LTQ), which operated in selective ion monitoring (SIM) modes set for targeted analytes and their internal standards (IS). All validation parameters were within acceptable ranges of analytical method validation guidelines. Intra- and inter-day assay precision and accuracy coefficients of variation were <3.1%, and recoveries for TMA and TMAO were 97–104%. The method developed uses a two-step procedure. Firstly, TMA and TMAO are analyzed without a purification step using a 5-min gradient cap-LC- SIMs analysis, then creatinine is analyzed using the same experimental conditions. The method is robust, highly sensitive, reproducible and has the high-throughput capability of detecting TMA, TMAO and creatinine at on-column concentrations as low as 28 pg/mL, 115 pg/mL and 1 ng/mL, respectively. The method is suitable for analysis of TMA, TMAO and creatinine in both male and female mouse urine.

The key benefits of the method are:

•

The small sample volume of urine required, which overcomes the difficulties of collecting sufficient volumes of urine at defined times.

•

No sample pre-treatment is necessary.

•

The quantification of TMA, TMAO and creatinine using the same cap-LC-MS method.

Volatile organic compounds in plasma for the diagnosis of esophageal adenocarcinoma: a pilot study

BACKGROUND AND AIMS

A noninvasive screening test that can detect esophageal adenocarcinoma (EAC) at an earlier stage could improve the prognosis associated with EAC. The role of plasma volatile organic compounds (VOCs) for the diagnosis of EAC has not been previously studied.

METHODS

Plasma samples were collected from subjects with EAC and GERD before endoscopy. Twenty-two preselected VOCs were analyzed with selected ion flow tube mass spectrometry.

RESULTS

The headspaces from 39 plasma samples (20 EAC, 19 GERD) were analyzed. The levels of 9 VOCs (acetonitrile, acrylonitrile, carbon disulfide, isoprene, 1-heptene, 3-methylhexane, [E]-2-nonene, hydrogen sulfide, and triethylamine) were significantly altered in EAC patients compared with GERD patients. A multivariable logistic regression analysis was performed to build a model for the prediction of EAC. The model identified patients with EAC with an area under the curve of 0.83 (95% confidence interval, 0.67-0.98).

CONCLUSIONS

Plasma VOCs may be useful in diagnosing EAC. Larger studies are needed to confirm our pilot study observations.

Trimethylamine and Trimethylamine N-Oxide, a Flavin-Containing Monooxygenase 3 (FMO3)-Mediated Host-Microbiome Metabolic Axis Implicated in Health and Disease

Flavin-containing monooxygenase 3 (FMO3) is known primarily as an enzyme involved in the metabolism of therapeutic drugs. On a daily basis, however, we are exposed to one of the most abundant substrates of the enzyme trimethylamine (TMA), which is released from various dietary components by the action of gut bacteria. FMO3 converts the odorous TMA to nonodorous TMA N-oxide (TMAO), which is excreted in urine. Impaired FMO3 activity gives rise to the inherited disorder primary trimethylaminuria (TMAU). Affected individuals cannot produce TMAO and, consequently, excrete large amounts of TMA. A dysbiosis in gut bacteria can give rise to secondary TMAU. Recently, there has been much interest in FMO3 and its catalytic product, TMAO, because TMAO has been implicated in various conditions affecting health, including cardiovascular disease, reverse cholesterol transport, and glucose and lipid homeostasis. In this review, we consider the dietary components that can give rise to TMA, the gut bacteria involved in the production of TMA from dietary precursors, the metabolic reactions by which bacteria produce and use TMA, and the enzymes that catalyze the reactions. Also included is information on bacteria that produce TMA in the oral cavity and vagina, two key microbiome niches that can influence health. Finally, we discuss the importance of the TMA/TMAO microbiome-host axis in health and disease, considering factors that affect bacterial production and host metabolism of TMA, the involvement of TMAO and FMO3 in disease, and the implications of the host-microbiome axis for management of TMAU.

Role of endoscopic retrograde cholangiopancreatography in the management of benign biliary strictures: What’s new?

Benign biliary strictures comprise a heterogeneous group of diseases. The most common strictures amenable to endoscopic treatment are post-cholecystectomy, post-liver transplantation, related to primary sclerosing cholangitis and to chronic pancreatitis. Endoscopic treatment of benign biliary strictures is widely used as first line therapy, since it is effective, safe, noninvasive and repeatable. Endoscopic techniques currently used are dilation, multiple plastic stents insertion and fully covered self-expandable metal stents. The main indication for dilation alone is primary sclerosing cholangitis related strictures. In the vast majority of the remaining cases, temporary placement of multiple plastic stents with/without dilation is considered the treatment of choice. Although this approach is effective, it requires multiple endoscopic sessions due to the short duration of stent patency. Fully covered self-expandable metal stents appear as a good alternative to plastic stents, since they have an increased radial diameter, longer stent patency, easier insertion technique and similar efficacy. Recent advances in endoscopic technique and various devices have allowed successful treatment in most cases. The development of novel endoscopic techniques and devices is still ongoing.

Research protocol for a diagnostic study of non-invasive exhaled breath analysis for the prediction of oesophago-gastric cancer

INTRODUCTION

Despite improvements in a range of chemo, radio and surgical therapies, the overall survival at 5 years from oesophago-gastric cancer remains poor and ranges from 10% to 30%. Early diagnosis is a key strategy to improve survival but early disease stage has non-specific symptoms that are very common while the warning clinical picture often indicates advanced disease. The aim of this research is to validate a breath test to predict oesophago-gastric cancer therefore allowing earlier diagnosis and introduction of treatment.

METHODS AND ANALYSIS

The study will include 325 patients and be conducted across four major oesophago-gastric cancer centres in London, UK. This research will utilise selected ion flow-tube mass spectrometry (SIFT-MS) exhaled breath analysis, for comparison of predicted cancer risk based on the previously developed volatile organic compound exhaled breath model, with endoscopic findings and histology biopsies. This will determine the overall diagnostic accuracy for non-invasive breath testing for the diagnosis of oesophago-gastric cancer.

ETHICS AND DISSEMINATION

Approval was gained from NRES Committee London, on 16 July 2014 (REC reference 14/LO/1136) for the completion of this study. Different methods of dissemination will be employed including international clinical and patient group presentations, and publication of research outputs in a high-impact clinical journal. This is to ensure that the findings from this research will reach patients, primary care practitioners, scientists, hospital specialists in gastroenterology, oncology and surgery, health policymakers and commissioners as well as NHS regulatory bodies.

TRIALS REGISTRATION NUMBER

UKCRN18063; Pre-results.

Exposure to environmental chemicals and heavy metals, and risk of pancreatic cancer

PURPOSE

Exposure to various chemicals and heavy metals has been associated with risk of different cancers; however, data on whether such exposures may increase the risk of pancreatic cancer (PC) are very limited and inconclusive. We examined PC risk with self-reported exposures to chemicals and heavy metals.

METHODS

The design was a clinic-based, case-control study of data collected from 2000 to 2014 at Mayo Clinic in Rochester, Minnesota, USA. Cases were rapidly ascertained patients diagnosed with pancreatic ductal adenocarcinoma (n = 2,092). Controls were cancer-free patients in primary care clinics (n = 2,353), frequency-matched to cases on age, race, sex, and state/region of residence. Cases and controls completed identical risk factor questionnaires, which included yes/no questions about regular exposure to pesticides, asbestos, benzene, chlorinated hydrocarbons, chromium, and nickel. Unconditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CI) comparing those who affirmed exposure to each of the chemicals/heavy metals to those who reported no regular exposure, adjusting for potential confounders.

RESULTS

Self-reported regular exposure to pesticides was associated with increased odds of PC (OR 1.21, 95% CI 1.02-1.44). Regular exposure to asbestos (OR 1.54, 95% CI 1.23-1.92), benzene (OR 1.70, 95% CI 1.23-2.35), and chlorinated hydrocarbons (OR 1.63, 95% CI 1.32-2.02) also was associated with higher odds of PC. Chromium and nickel exposures were not significantly associated with PC.

CONCLUSIONS

These findings add to the limited data suggesting that exposure to pesticides, asbestos, benzene, and chlorinated hydrocarbons may increase PC risk. They further support the importance of implementing strategies that reduce exposure to these substances.

Bile proteomics for differentiation of malignant from benign biliary strictures: a pilot study

BACKGROUND

Determining the etiology of biliary strictures is challenging, and the sensitivities of the current tests to diagnose them are low. Protein biomarkers in bile, in combination with other tests, may improve sensitivity in diagnosing biliary strictures.

OBJECTIVE

To analyse the differential abundance of proteins in benign and malignant biliary strictures through proteomic analysis of bile.

METHODS

In this prospective, cross-sectional study, bile was aspirated in 24 patients undergoing endoscopic retrograde cholangiopancreatography (ERCP) including six patients with primary sclerosing cholangitis (PSC), three with cholangiocarcinoma (CCA), ten with pancreatic cancer, and five with benign biliary conditions. Liquid chromatography/mass spectrometry was used to examine the bile for differential abundance of protein biomarkers. The relative abundance of various proteins was compared in the malignant vs. benign groups and in CCA vs. PSC.

RESULTS

The majority of the proteins identified in bile were similar to those of the plasma (plasma proteins) and certain proteins were differentially expressed among the different groups (CCA, pancreatic cancer, PSC or benign). A total of 18 proteins were identified as being more abundant in the malignant group (CCA and pancreatic cancer) than in the benign strictures group, including myeloperoxidase, complement C3, inter-alpha-trypsin inhibitor heavy chain H4, apolipoprotein B-100, and kininogen-1 isoform 2. A total of 30 proteins were identified to be less abundant in the malignant group than in the benign group, including trefoil factor 2, superoxide dismutase [Cu-Zn], kallikrein-1, carboxypeptidase B and trefoil factor 1.

CONCLUSIONS

Protein biomarkers in bile may differentiate malignant from benign biliary strictures. Larger studies are warranted to validate these observations.

Biomarkers in bile-complementing advanced endoscopic imaging in the diagnosis of indeterminate biliary strictures

Biliary strictures present a diagnostic challenge and a conundrum, particularly when an initial work up including abdominal imaging and endoscopic retrograde cholangiopancreatography based sampling are non-diagnostic. Advances in endoscopic imaging have helped us diagnose these strictures better. However, even with modern technology, some strictures remain a diagnostic challenge. The proximity of bile fluid to the bile duct epithelia makes it an attractive option to investigate for bio-markers, which might be representative of the functions/abnormal changes taking place in the biliary system. A number of biomarkers in bile have been discovered recently in approaching biliary strictures with their potential future diagnostic utility, further supported by the immunohistochemical analysis of the resected tissue specimens. Novel biliary biomarkers especially carcinoembryonic cell adhesion molecule 6 and neutrophil gelatinase-associated lipocalin seem promising in differentiating malignant from benign biliary strictures. Recent developments in lipidomic profiling of bile are also very promising. Biliary biomarkers appear to complement endoscopic imaging in diagnosing malignant etiologies of biliary stricture. Future studies addressing these biomarkers need to be incorporated to the current endoscopic techniques to determine the best approach in determining the etiology of biliary strictures.

Volatile organic compounds in bile for early diagnosis of cholangiocarcinoma in patients with primary sclerosing cholangitis: a pilot study

BACKGROUND

The diagnosis of cholangiocarcinoma (CCA) in patients with primary sclerosing cholangitis (PSC) is particularly difficult. The role of volatile organic compounds (VOCs) for diagnosis of CCA in patients with PSC is not known.

OBJECTIVE

Our aim was to identify potential VOCs in the headspaces (gas above the sample) in bile that may predict CCA in patients with PSC.

DESIGN

Prospective cross-sectional study.

SETTING

Referral center.

PATIENTS

A total of 32 patients undergoing ERCP for PSC and for CCA complicating PSC.

INTERVENTIONS

ERCP, bile aspiration.

MAIN OUTCOME MEASUREMENTS

Selected ion flow tube mass spectrometry was used to analyze the concentration of 22 prevalent VOCs in bile samples. Logistic regression analysis was performed to build a predictive model for diagnosis of CCA.

RESULTS

Levels of several compounds (ethanol, acrylonitrile, acetonitrile, acetaldehyde, benzene, carbon disulfide, dimethyl sulfide, 2-propranolol) were significantly different in patients with CCA complicating PSC compared with those having PSC (P < .05). By using receiver operating characteristic curve analysis, we developed a model for the diagnosis of CCA adjusted for age and sex based on VOC levels of acrylonitrile, 3-methyl hexane, and benzene. The model (2.3239*log [acrylonitrile] + 0.9871*log [3-methyl hexane] + 0.8448*log [benzene]) < -0.12 identified the patients with CCA (area under the curve [AUC] = 0.89), with 90.5% sensitivity and 72.7% specificity (P = .02).

LIMITATIONS

Sample size.

CONCLUSION

The measurement of VOCs in biliary fluid may be useful to diagnose CCA in patients with PSC. A larger study with a longitudinal study design is required to confirm our pilot observations to diagnose CCA early in patients with PSC. (

CLINICAL TRIAL REGISTRATION NUMBER

NCT01565460.).

Comparative effectiveness of pyruvate kinase M2 in bile, serum carbohydrate antigen 19-9, and biliary brushings in diagnosing malignant biliary strictures

BACKGROUND

The role of M2-PK (pyruvate kinase) in bile has not been studied in comparison with brushings and carbohydrate antigen (CA) 19-9 in the diagnosis of malignant biliary strictures.

AIM

To compare the diagnostic accuracy of biliary M2-PK with cytology and serum CA 19-9 METHODS: In this prospective cross-sectional study, bile was aspirated in 74 patients (discovery and validation cohort) undergoing endoscopic retrograde cholangiopancreatography. Levels of M2-PK were measured in bile and compared to brushings for cytology and CA 19-9.

RESULTS

In the discovery cohort, the median bile M2-PK levels were significantly elevated in patients with malignant biliary strictures [187.9 U/l (interquartile range (IQR) 3.5, 3626.8)] compared to those with benign biliary conditions and primary sclerosing cholangitis [0 U/l (IQR 0, 15)] (P = 0.007). A M2-PK cutoff value of 109.1 U/l distinguished malignant from benign conditions with a sensitivity and specificity of 52.9 and 94.1 %, respectively, and area under curve (AUC) of 0.77. The sensitivity of CA 19-9 and brushings in diagnosing cancer was 52.9 % and 11.1 % and specificity 94.1 and 100 %, respectively. The presence of elevated M2-PK >109.1 U/l or CA 19-9 >33 U/ml or positive brushing was 88.2 % sensitive and 88.2 % specific, AUC of 0.89 in the diagnosis of malignancy. The diagnostic accuracy was confirmed in the validation cohort.

CONCLUSIONS

As a stand-alone factor, none of the markers were able to distinguish benign from malignant biliary strictures with a high sensitivity. However, a combination was highly sensitive in diagnosing malignant biliary strictures.

Comparative effectiveness of biliary brush cytology and intraductal biopsy for detection of malignant biliary strictures: a systematic review and meta-analysis

BACKGROUND

Evaluation of indeterminate biliary strictures typically involves collection and analysis of tissue or cells. Brush cytology and intraductal biopsies that are routinely performed during ERCP to assess malignant-appearing biliary strictures are limited by relatively low sensitivity.

OBJECTIVE

To study the comparative effectiveness of brushings for cytology and intraductal biopsies in the etiology of biliary strictures.

DESIGN

Meta-analysis.

SETTING

Referral center.

PATIENTS

PUBMED and Embase databases were reviewed for studies published to April 2014 where diagnostic correlation of histology was available.

INTERVENTION

Database and review of study findings.

MAIN OUTCOME MEASUREMENTS

Sensitivity and specificity.

RESULTS

The pooled sensitivity and specificity of brushings for the diagnosis of malignant biliary strictures was 45% (95% confidence interval [CI], 40%-50%) and 99% (95% CI, 98%-100%), respectively. The pooled diagnostic odds ratio to detect malignant biliary strictures was 33.43 (95% CI, 14.29-78.24). For intraductal biopsies, the pooled sensitivity and specificity were 48.1% (95% CI, 42.8%-53.4%) and 99.2% (95% CI, 97.6%-99.8%), respectively. The pooled diagnostic odds ratio to detect malignant biliary strictures was 43.18 (95% CI, 19.39-95.83). A combination of both modalities only modestly increased the sensitivity (59.4%; 95% CI, 53.7%-64.8%) with a specificity of 100% (95% CI, 98.8%-100.0%). The Begg-Mazumdar and Egger tests indicated a low potential for publication bias.

LIMITATIONS

Inclusion of low-quality studies.

CONCLUSION

Our study suggests that both brushings and biopsy are comparable and have limited sensitivity for the diagnosis of malignant biliary strictures. A combination of both only modestly increases the sensitivity.

Biliary strictures: diagnostic considerations and approach

Biliary strictures present a diagnostic challenge, especially when no etiology can be ascertained after laboratory evaluation, abdominal imaging and endoscopic retrograde cholangiopancreatography (ERCP) sampling. These strictures were traditionally classified as indeterminate strictures, although with advances in endoscopic techniques and better understanding of hepato-biliary pathology, more are being correctly diagnosed. The implications of missing a malignancy in patients with biliary strictures—and hence delaying surgery—are grave but a significant number of patients (up to 20%) undergoing surgery for suspected biliary malignancy can have benign pathology. The diagnostic approach to these patients involves detailed history and physical examination and depends on the presence or absence of jaundice, level of obstruction, and presence or absence of a mass lesion. While abdominal imaging helps to find the level of obstruction and provides a ‘road map' for further endoscopic investigations, tissue diagnosis is usually needed to make decisions on management. Initially ERCP was the only modality to investigate these strictures but now, with the development of endoscopic ultrasound with fine needle aspiration and the availability of newer techniques such as intraductal ultrasound, single-operator cholangioscopy and confocal laser endomicroscopy, the diagnostic approach to biliary strictures has changed significantly. In this review, we will focus on the decision-making process for patients with biliary strictures and discuss the key decision points that should dictate further diagnostic investigations at each step.