The potential diagnostic use of K-ras codon 12 and p53 alterations in brush cytology from the pancreatic head region

Precision cytopathology: expanding opportunities for biomarker testing in cytopathology

Precision cytopathology refers to therapeutically linked biomarker testing in cytopatology, a dynamically growing area of the discipline. This review describes basic steps to expand precision cytopathology services. Focusing exclusively on solid tumors, the review is divided into four sections: Section 1: Overview of precision pathology- opportunities and challenges; Section 2: Basic steps in establishing or expanding a precision cytopathology laboratory; Section 3: Cytopathology specimens suitable for next generation sequencing platforms; and Section 4: Summary. precision cytopathology continues to rapidly evolve in parallel with expanding targeted therapy options. Biomarker assays (companion diagnostics) comprise a multitude of test types including immunohistochemistry, in situ hybridization and molecular genetic tests such as PCR and next generation sequencing all of which are performable on cytology specimens. Best practices for precision cytopathology will incorporate traditional diagnostic approaches allied with careful specimen triage to enable successful biomarker analysis. Beyond triaging, cytopathologists knowledgeable about molecular test options and capabilities have the opportunity to refine diagnoses, prognoses and predictive information thereby assuming a lead role in precision oncology biomarker testing.

Bile duct brushing cytology: Cytohistologic/fine-needle aspiration correlation and diagnostic pitfalls

INTRODUCTION

Bile duct brushings are a mainstay in the work-up of patients who present with clinical findings of pancreaticobiliary disease. This study presents the University of Wisconsin Hospital and Clinics Cytopathology Laboratory's experience over a 10.5-year period with histologic and fine-needle aspiration (FNA) correlation.

MATERIALS AND METHODS

From January 1, 2005, through June 30, 2015, 676 bile duct brushings were processed, of which 408 (60%) were negative, 84 (12%) were atypical, 65 (10%) were suspicious, and 119 (18%) were malignant. Histologic and FNA follow-up was available in 285 (42%) of the cases and forms the basis of this study.

RESULTS

There were 59 (21%) positive, 38 (13%) suspicious, 54 (19%) atypical, and 134 (47%) negative bile duct brushings with follow-up. Of the 59 positive cases, 57 (97%) were malignant and 2 (3%) were negative on histologic/FNA follow-up. Thirty-three (87%) of the suspicious brushing were malignant on follow-up and 5 (13%) were negative; 43 (80%) of the atypical brushings were malignant and 11 (20%) were negative; and 94 (70%) of the negative brushings were malignant and 40 (30%) were negative on histologic/FNA follow-up. The sensitivity was 38%; specificity, 95%; positive predictive value, 97%; negative predictive value, 30%.

CONCLUSIONS

Bile duct brushing cytology is highly specific in the detection of malignant pancreatobiliary lesions with few false positives, but has low sensitivity with many false negatives.

The need for effective pancreatic cancer detection and management: a biomarker-based strategy

Pancreatic cancer (Pa) is generally a very aggressive disease, with few effective approaches available for early diagnosis or therapy. These factors, combined with the aggressiveness and chemoresistance of Pa, results in a bleak outcome post-diagnosis. Cancer-related biomarkers have established capabilities for diagnosis, prognosis and screening and can be exploited to aid in earlier less-invasive diagnosis and optimization of targeted therapies. Pa has only one US FDA-approved biomarker, CA19-9, which has significant limitations. Hence, it is vital that novel biomarkers are identified and validated to diagnose, treat, control and monitor Pa. This review focuses on existing and potential Pa-associated markers and discusses how they may be applied in cohort for improved management of Pa.

Utilization of ancillary studies in the cytologic diagnosis of biliary and pancreatic lesions: The Papanicolaou Society of Cytopathology Guidelines

The Papanicolaou Society of Cytopathology has developed a set of guidelines for pancreatobiliary cytology including indications for endoscopic ultrasound guided fine needle aspiration, terminology and nomenclature of pancreatobiliary disease, ancillary testing and post-biopsy management. All documents are based on the expertise of the authors, a review of the literature, discussion of the draft document at several national and international meetings and synthesis of selected online comments of the draft document. This document presents the results of these discussions regarding the use of ancillary testing in the cytologic diagnosis of biliary and pancreatic lesions. Currently, fluorescence in-situ hybridization (FISH) appears to be the most clinically relevant ancillary technique for cytology of bile duct strictures. The addition of FISH analysis to routine cytologic evaluation appears to yield the highest sensitivity without loss in specificity. Loss of immunohistochemical staining for the protein product of the SMAD4 gene and positive staining for mesothelin support a diagnosis of ductal adenocarcinoma. Immunohistochemical markers for endocrine and exocrine differentiation are sufficient for a diagnosis of endocrine and acinar tumors. Nuclear staining for beta-catenin supports a diagnosis of solid-pseudopapillary neoplasm. Cyst fluid analysis for amylase and carcinoembryonic antigen aids in the pre-operative classification of pancreatic cysts. A number of gene mutations (KRAS, GNAS, von Hippel-Lindau, RNF43 and CTNNB1) may be of aid in the diagnosis of cystic neoplasms. Other ancillary techniques do not appear to improve diagnostic sensitivity sufficiently to justify their increased costs.

Utilization of ancillary studies in the cytologic diagnosis of biliary and pancreatic lesions: the Papanicolaou Society of Cytopathology guidelines for pancreatobiliary cytology

The Papanicolaou Society of Cytopathology has developed a set of guidelines for pancreatobiliary cytology including indications for endoscopic ultrasound-guided fine-needle aspiration, terminology and nomenclature of pancreatobiliary disease, ancillary testing, and post-biopsy management. All documents are based on the expertise of the authors, a review of the literature, discussions of the draft document at several national and international meetings, and synthesis of selected online comments of the draft document. This document presents the results of these discussions regarding the use of ancillary testing in the cytologic diagnosis of biliary and pancreatic lesions. Currently, fluorescence in situ hybridization (FISH) appears to be the most clinically relevant ancillary technique for cytology of bile duct strictures. The addition of FISH analysis to routine cytologic evaluation appears to yield the highest sensitivity without loss in specificity. Loss of immunohistochemical staining for the protein product of the SMAD4 gene and positive staining for mesothelin support a diagnosis of ductal adenocarcinoma. Immunohistochemical markers for endocrine and exocrine differentiation are sufficient for a diagnosis of endocrine and acinar tumors. Nuclear staining for beta-catenin supports a diagnosis of solid-pseudopapilary neoplasm. Cyst fluid analysis for amylase and carcinoembryonic antigen aids in the preoperative classification of pancreatic cysts. Many gene mutations (KRAS, GNAS, VHL, RNF43, and CTNNB1) may be of aid in the diagnosis of cystic neoplasms. Other ancillary techniques do not appear to improve diagnostic sensitivity sufficiently to justify their increased costs.

Molecular markers in pancreatic cancer diagnosis

Pancreatic ductal adenocarcinoma (PDAC) represents a fatal neoplasia with a high mortality rate. Effective early detection methods are needed since this is the best way to cure this disease. During the last several years, many investigations focused on determining relevant biomarkers that may be present during early stages of pancreatic tumor development. Although several biomarkers have been proposed for pancreatic cancer detection, the clinical applicability has been confusing. Currently, although CA19-9 is one test used, the sensitivity and specificity for the disease are less than optimal. Here, we review several new potential serum, plasma and stool markers that are currently under evaluation. Although these have not been sufficiently validated for routine clinical use, these markers could prove valuable with further investigations. We keep the hope that a combination of some of these novel biomarkers can be a useful tool for early PDAC diagnosis before image techniques and/or patient's symptoms reveal disease in an incurable state.

Beyond cytomorphology: expanding the diagnostic potential for biliary cytology

Malignancy of the extrahepatic biliary tract is a difficult and crucial diagnosis, both clinically and pathologically. Cytologic evaluation of brushings obtained endoscopically from the biliary tree is currently the standard of care in most institutions. However, bile duct brushing cytology has been plagued by low sensitivity and interpretative difficulties in differentiating reactive from malignant cytology. This review outlines both the difficulties presented by cytomorphology and the potential of new diagnostic techniques that promise to increase sensitivity without sacrificing the high specificity of cytomorphology.

Focal intrahepatic strictures: a review of diagnosis and management

INTRODUCTION

Focal intrahepatic strictures are becoming more common owing to more prevalent and accurate cross-sectional imaging. However, data relating to their management are lacking. The purpose of the present review was to synthesize the current evidence regarding these lesions and to formulate a strategy for diagnosis and management.

METHODS

A literature search of relevant terms was performed using Medline. References of papers were subsequently searched to obtain older literature.

RESULTS

Focal intrahepatic strictures involve segmental hepatic ducts and/or left and right main hepatic ducts during their intrahepatic course. Most patients are asymptomatic while the minority present with vague abdominal pain or recurrent sepsis and only rarely with jaundice. Investigations used to distinguish benign from malignant aetiologies include blood tests (CEA, Ca19.9), imaging studies [ultrasonography (US), computed tomography (CT), magnetic resonance cholangiopancreatography (MRCP) and fluorodeoxyglucose-positron emission tomography (FDG-PET)], endoscopic modalities [endoscopic retrograde cholangiopancreatography (ERCP)/endoscopic ultrasound (EUS)/cholangioscopy] and tissue sampling (brush cytology/biopsy).

CONCLUSIONS

A focal intrahepatic stricture requires thorough investigation to exclude malignancy even in patients with a history of biliary surgery, hepatolithiasis or parasitic infection. If during the investigative process a diagnosis or suspicion of malignancy is demonstrated then surgical resection should be performed. If all diagnostic modalities suggest a benign aetiology, then cholangioscopy with targeted biopsies should be performed.

Pancreatic cancer screening

Accumulating data indicate that clinically available abdominal imaging tests such as EUS and MRI/MRCP can detect asymptomatic precursor benign (IPMN, PanIN) and invasive malignant pancreatic neoplasms, such as ductal adenocarcinoma, in individuals with an inherited predisposition. These asymptomatic FPCs detected have been more likely to be resectable, compared to symptomatic tumors. The most challenging part of screening high-risk individuals is the selection of individuals with high-grade precursor neoplasms for preventive treatment (ie, surgical resection before development of invasive cancer). Ongoing and future research should focus on formulating and validating a model for FPC risk and neoplastic progression using patient characteristics, imaging, and biomarkers. The comparative cost and effectiveness of various approaches for screening and surveillance of high-risk individuals also deserves study. For now, screening is best performed in high-risk individuals within the research protocols in academic centers with multidisciplinary teams with expertise in genetics, gastroenterology, radiology, surgery, and pathology.

Overcoming drug resistance in pancreatic cancer

INTRODUCTION

Pancreatic cancer has the worst survival rate of all cancers. The current standard care for metastatic pancreatic cancer is gemcitabine, however, the success of this treatment is poor and overall survival has not improved for decades. Drug resistance (both intrinsic and acquired) is thought to be a major reason for the limited benefit of most pancreatic cancer therapies.

AREAS COVERED

Previous studies have indicated various mechanisms of drug resistance in pancreatic cancer, including changes in individual genes or signaling pathways, the influence of the tumor microenvironment, and the presence of highly resistant stem cells. This review summarizes recent advances in the mechanisms of drug resistance in pancreatic cancer and potential strategies to overcome this.

EXPERT OPINION

Increasing drug delivery efficiency and decreasing drug resistance is the current aim in pancreatic cancer treatment, and will also benefit the treatment of other cancers. Understanding the molecular and cellular basis of drug resistance in pancreatic cancer will lead to the development of novel therapeutic strategies with the potential to sensitize pancreatic cancer to chemotherapy, and to increase the efficacy of current treatments in a wide variety of human cancers.

Pancreatic intraepithelial neoplasia and pancreatic tumorigenesis: of mice and men

CONTEXT

Pancreatic cancer has a poor prognosis with a 5-year survival of less than 5%. Early detection is at present the only way to improve this outlook. This review focuses on the recent advances in our understanding of pancreatic carcinogenesis, the scientific evidence for a multistaged tumor progression, and the role genetically engineered mouse models can play in recapitulating the natural course and biology of human disease.

OBJECTIVES

To illustrate the stepwise tumor progression of pancreatic cancer and genetic alterations within the different stages of progression and to review the findings made with genetically engineered mouse models concerning pancreatic carcinogenesis.

DATA SOURCES

A review of recent literature on pancreatic tumorigenesis and genetically engineered mouse models.

CONCLUSIONS

Pancreatic cancer develops through stepwise tumor progression in which preinvasive stages, called pancreatic intraepithelial neoplasia, precede invasive pancreatic cancer. Genetic alterations in oncogenes and tumor suppressor genes underlying pancreatic cancer are also found in pancreatic intraepithelial neoplasia. These mutations accumulate during progression through the consecutive stages of pancreatic intraepithelial neoplasia lesions. Also in genetically engineered mouse models of pancreatic ductal adenocarcinoma, tumorigenesis occurs through stepwise progression via consecutive mouse pancreatic intraepithelial neoplasia, and these models provide important tools for clinical applications. Nevertheless differences between mice and men still remain.

Genetic and epigenetic alterations of familial pancreatic cancers

BACKGROUND

Little is known about the genetic and epigenetic changes that contribute to familial pancreatic cancers. The aim of this study was to compare the prevalence of common genetic and epigenetic alterations in sporadic and familial pancreatic ductal adenocarcinomas.

METHODS

DNA was isolated from the microdissected cancers of 39 patients with familial and 36 patients with sporadic pancreatic adenocarcinoma. KRAS2 mutations were detected by BstN1 digestion and/or cycle sequencing. TP53 and SMAD4 status were determined by immunohistochemistry on tissue microarrays of 23 archival familial pancreatic adenocarcinomas and in selected cases by cycle sequencing to identify TP53 gene mutations. Methylation-specific PCR analysis of seven genes (FoxE1, NPTX2, CLDN5, P16, TFPI-2, SPARC, ppENK) was done on a subset of fresh-frozen familial pancreatic adenocarcinomas.

RESULTS

KRAS2 mutations were identified in 31 of 39 (80%) of the familial versus 28 of 36 (78%) of the sporadic pancreatic cancers. Positive immunolabeling for p53 was observed in 57% of the familial pancreatic cancers and loss of SMAD4 labeling was observed in 61% of the familial pancreatic cancers, rates similar to those observed in sporadic pancreatic cancers. The mean prevalence of aberrant methylation in the familial pancreatic cancers was 68.4%, which was not significantly different from that observed in sporadic pancreatic cancers.

CONCLUSION

The prevalence of mutant KRAS2, inactivation of TP53 and SMAD4, and aberrant DNA methylation of a seven-gene panel is similar in familial pancreatic adenocarcinomas as in sporadic pancreatic adenocarcinomas. These findings support the use of markers of sporadic pancreatic adenocarcinomas to detect familial pancreatic adenocarcinomas.

Mesothelin is a malignant factor and therapeutic vaccine target for pancreatic cancer

Given the high fatality rate of pancreatic cancer, an effective treatment for this devastating disease is urgently needed. We have shown that mesothelin expression was higher in human pancreatic cancer cells than in human pancreatic duct epithelial cells, and mesothelin mRNA was substantially overexpressed in 18 of 21 (86%) clinical pancreatic adenocarcinoma specimens when compared with the surrounding normal tissues. However, the biological functions of mesothelin in tumor progression are not clearly understood. Here we studied the effects of mesothelin overexpression in pancreatic cancer cell proliferation and migration in vitro and pancreatic cancer progression in vivo. We found that forced expression of mesothelin significantly increased tumor cell proliferation and migration by 90% and 300%, respectively, and increased tumor volume by 4-fold in the nude mice xenograft model when compared with the vector control cell line. Silencing of mesothelin inhibited cell proliferation and migration in pancreatic cancer cells and ablated tumor progression in vivo. Vaccination with chimeric virus-like particles that contain human mesothelin substantially inhibited tumor progression in C57BL/6J mice. The increases in mesothelin-specific antibodies and CTL activity and the decrease in regulatory T cells correlated with reduced tumor progression and prolonged survival. This study revealed novel functions of mesothelin and suggested a new therapeutic vaccine strategy whereby mesothelin is targeted to control pancreatic cancer progression.

Diagnosis of biliary tract lesions by histological sectioning of brush bristles as alternative to cytological smearing

AIM

To increase the diagnostic potential of endoscopic biliary tract brushing, we devised an approach alternative to cytological smearing, leading to the preoperative histological examination of the collected material.

METHODS

One hundred twelve consecutive biliary brush specimens were included. All patients presented a stricture of the biliary tract, leading to a diagnostic procedure by brushing. Immediately following brushing, the endoscopist immersed the brush into methanol and sent it to the pathology laboratory. The brush was introduced into a cassette for paraffin embedding and sections parallel to the long axis of brush were cut until the metal wire was almost reached, then the block was rotated and new sections were obtained from the opposite side. Samples of the mucosa, inflammatory cell aggregates, small fragments of carcinomas, or isolated cells were observed, and displayed an optimal fixation, allowing a definite diagnosis that proved mandatory for therapy in the vast majority of cases (99.1%).

RESULTS

The results obtained in 112 consecutive cases using such technique compared with final histological diagnosis proved: 91% sensitivity, 100% specificity, 100% positive predictive value (PPV), and 87% negative predictive value (NPV) (P < 0.001). In nonoperated patients, the clinical diagnosis after at least 6 months of follow-up showed: 95.5% sensitivity, 100% specificity, 100% PPV, and 88.2% NPV (P < 0.001).

CONCLUSION

Such novel approach to the preoperative diagnosis of biliary tract lesions proved to be highly sensitive and specific, limiting the inadequate preoperative diagnoses to less than 1%.

Molecular markers of pancreatic cancer: development and clinical relevance

BACKGROUND

The prognosis of pancreatic cancer remains poor, mainly because of its aggressive biological behaviour and late clinical diagnosis, which precludes the application of appropriate curative therapies. Therefore, one of the major goals in clinical pancreatology is to find molecular markers, specific and sensitive enough to make an early and correct diagnosis of pancreatic cancer, before it has disseminated and become untreatable.

OBJECTIVE

This overview article explores the potential utility of current molecular markers for the diagnosis of pancreatic cancer.

RESULTS

There is a wide array of serum-based and tissue-based markers for pancreatic cancer. Serum-based molecular markers include CA 19-9, CA 125, M2-PK and secreted proteins. A tissue can be used to test genetic mutations such as K-ras, inactivation of tumour suppressor genes (e.g. p16, p53), mucins, telomerase activity, growth factors, DNA methylation, and global gene expression of cDNA microarrays, mitochondrial mutations and proteomics. None of these markers is currently useful for the detection of early pancreatic cancer. In clinical practice, the most commonly accepted use of CA 19-9 is to assess the prognosis and monitor the response to therapy.

CONCLUSIONS

Many molecular markers have been proposed for the early diagnosis of PC, but most are not ready to be included as part of the routine diagnostic algorithm because they still lack sensitivity, specificity or reproducibility. CA 19-9 remains the most useful molecular marker for the diagnosis and follow-up of clinically and radiological evident pancreatic cancer.

Identifying molecular markers for the early detection of pancreatic neoplasia

Pancreatic cancer is the fourth most common cause of cancer death in the United States. There is a great need for better diagnostic markers of pancreatic neoplasia. Better markers would improve the early diagnosis of pancreatic cancer and allow more patients to undergo curative surgical resection. Identifying individuals at high risk of developing pancreatic cancer and applying markers that could identify precancerous lesions of the pancreas in these individuals could allow such lesions to be resected before the development of pancreatic cancer. As we continue to characterize the genetic, epigenetic, and proteomics alterations that occur in pancreatic cancers and their percursors, better diagnostic markers of pancreatic cancer are expected to follow.

Molecular diagnostic testing as an adjunct to morphologic evaluation of pancreatic ductal system brushings: Potential augmentation for diagnostic sensitivity

Malignancies arising from the pancreatic and biliary ductal systems present the gastroenterologist and pathologist with diagnostic challenges. Tumors of the pancreatic and/or biliary ductal system may present as either duct strictures or mass lesions. When lesions present as strictures without associated demonstrable masses, brushing cytology may represent the only reasonable diagnostic technique aside from open biopsy. Diagnostic sensitivities for brushing cytology have ranged from 18 to 90%. Positive diagnoses of malignancy are of great clinical value but a negative result is of relatively little clinical aid when the radiographic or clinical findings are suspicious for a malignancy.A variety of techniques have been used in an attempt to improve diagnostic sensitivity for brushing cytology. These have included immunohistochemistry and various molecular diagnostic techniques. Using the high resolution melting curve technique, we performed mutational analysis on 20 bile duct brushing specimens for mutations in p53, K-ras, BRAF, and EGFR genes. Eleven specimens had corresponding surgical specimens, which were similarly analyzed. Our series included twelve adenocarcinomas, one islet cell tumor, one case of dysplasia, and six benign cases. K-ras mutations were found in cytology specimens of 3 out of 12 malignancies. No EGFR or B-raf mutations were detected and only a single p53 mutation in an adenocarcinoma was detected in the corresponding cytology specimen. No mutations were detected in benign lesions or in the dysplasia. Only 8% of specimens from adenocarcinomas had p53 mutations and only 33% of cases had K-ras mutations. Mutational analysis did not appear to improve the cytologic detection of adenocarcinoma by bile duct brushings.

K-Ras and microsatellite marker analysis of fine-needle aspirates from intraductal papillary mucinous neoplasms of the pancreas

Preoperative diagnosis of pancreatic cystic lesions is difficult despite the combination of cytomorphology, radiographic imaging characteristics, and fluid tumor markers such as carcinoembryonic antigen. Intraductal papillary mucinous neoplasms (IPMNs) represent a subset of preinvasive pancreatic cystic neoplasms and are associated with accumulated genetic mutations, especially K-ras and tumor suppressor genes such as p53. Application of molecular techniques to cyst fluid obtained by endoscopic ultrasound guided fine-needle aspiration (EUSFNA) may contribute to preoperative assessment. Sixteen patients with pancreatic cystic lesions had cyst fluid obtained by preoperative pancreatic EUSFNA or intraoperative aspiration. All patients subsequently underwent surgical resection of the pancreas and IPMN was documented in all (6 adenomas, 6 borderline tumors, and 4 carcinomas). DNA was extracted from the cyst fluids and mutational analysis for K-ras point mutations and loss of heterozygosity (LOH) analysis using a preselected panel of genomic loci were performed. LOH was observed in 3 of 4 carcinomas as compared to 4 of 11 adenomas and borderline lesions (1 was QNS). LOH and K-ras mutations were both acquired in 2 of 4 carcinomas and in 1 of 12 adenoma/borderline lesions. Although the study is small, molecular analysis for LOH and K-ras mutations is useful in the preoperative evaluation of cystic pancreatic lesions. Increasing degree of neoplasia appears to correlate with increased genetic abnormality using a panel of selected genomic markers.

Pancreatic and bile duct brushing cytology in 1000 cases: review of findings and comparison of preparation methods

BACKGROUND

Duct brushing cytology is an important tool in evaluation of the extrahepatic biliary tract and large pancreatic ducts. The emergence of neoadjuvant therapies underscores the importance of accurate preoperative diagnosis by noninvasive means. Liquid-based preparation methods, such as ThinPrep, have become popular for nongynecologic cytology specimens.

METHODS

Findings from bile and pancreatic duct brushings were reviewed over the 10-year period of 1994-2003. Cytologic material, imaging reports, and clinical data were reviewed and pathologic and clinical follow-up data were obtained. The slides were prepared by direct smear only (18.8%), direct smear plus cytospin (14.4%), or direct smear plus ThinPrep (66.8%).

RESULTS

A total of 1118 specimens were identified (1008 bile duct, 110 pancreatic duct) from 864 patients. The cytologic findings were: 53.5% negative, 16.5% malignant, 18.2% suspicious for malignancy, 11% atypical/inconclusive, 0.8% inadequate. Follow-up in the form of either histology or at least 6 months clinical observation was available for 82.2% of cases (n = 971). Overall operating characteristics were: 52.6% sensitivity, 99.4% specificity, 98.9% positive predictive value, 67.1% negative predictive value, and 75.7% accuracy. Diagnostic agreement between cytology and follow-up was the main variable analyzed. Agreement was significantly affected by characteristics of the sampled lesion, with ductal narrowing having the lowest rate of malignancy. In addition, the ThinPrep method showed superior sensitivity and accuracy compared with other preparation methods (P = .02). Nonsignificant associations were noted for patient age and gender, site of lesion, and the presence of either stones or prior stent.

CONCLUSION

In a large dataset from a single institution, brushing cytology showed modest sensitivity and high specificity. Diagnostic agreement was considerably better for benign cases. The combination of direct smear and the ThinPrep method showed superior sensitivity and accuracy.

Molecular biomarkers: their increasing role in the diagnosis, characterization, and therapy guidance in pancreatic cancer

The rapidly expanding knowledge of the pathogenesis of pancreatic cancer at the molecular level is providing new targets for disease characterization, early diagnosis, and drug discovery and development. Gene mutation analysis has provided insight on the pathogenesis and progression from preinvasive lesions to invasive cancer. Gene and protein expression profiling has advanced our understanding of pancreatic ductal adenocarcinoma identifying genes that are highly expressed in pancreatic cancers, providing more insight into the clinicopathologic features of pancreatic cancer, and revealing novel features related to the process of tissue invasion by these tumors. The increasing knowledge of the pathway activation profile in pancreatic cancer is yielding new targets but also new markers to select patients and guide and predict therapy efficacy. The discovery of genetic factors of which the presence predisposes pancreatic cancer to successful targeting, such as the association of BRCA2/Fanconi anemia genes defects and sensitivity to mitomycin C, will eventually lead to a more individualized treatment approach. In summary, several decades of intensive research have originated multiple factors or biomarkers that are likely to be helpful in the diagnosis, characterization, and therapy selection of pancreatic cancer patients. A deep understanding of the relative relevance of each biomarker will be key to efficiently diagnose this disease and direct our patients towards the drugs more likely to be of benefit based on their particular profile. The development of new preclinical models is of paramount importance to achieve these goals.

Comparison of the novel quantitative ARMS assay and an enriched PCR-ASO assay for K-ras mutations with conventional cytology on endobiliary brush cytology from 312 consecutive extrahepatic biliary stenoses

BACKGROUND

Extrahepatic biliary stenosis (EBS) has malignant and benign causes. Patients with EBS are at risk of having or developing malignancy. Accurate diagnostic tests for early detection and surveillance are needed. The sensitivity of biliary cytology for malignancy is low. K-ras mutation analysis on brush cytology is a valuable adjunct, but specificity is low. A quantitative test for K-ras mutations has been developed: the amplification refractory mutation system (ARMS).

AIM

To assess the test characteristics and additional value of ARMS in diagnosing the cause of EBS.

METHODS

Brush samples from endoscopic retrograde cholangiopancreatography were collected from 312 patients with EBS. K-ras mutation analysis was performed using ARMS-allele specific amplification was coupled with real time fluorescent detection of PCR products. Results were compared with conventional cytology and K-ras mutation analysis using allele specific oligonucleotide (ASO) hybridisation, and evaluated in view of the final diagnosis.

RESULTS

The test characteristics of ARMS and ASO largely agreed. Sensitivity for detecting malignancy was 49% and 42%, specificity 93% and 88%, and positive predictive value (PPV) 96% and 91%, respectively. The sensitivity of ARMS and cytology combined was 71%, and PPV was 93%. The specificity of ARMS could be increased to 100% by setting limits for the false positives, but reduced sensitivity from 49% to 43%.

CONCLUSIONS

ARMS can be considered supplementary to conventional cytology, and comparable to ASO in diagnosing malignant EBS. A specificity of 100% can be achieved with ARMS, which should be considered in the surveillance of patients at risk for pancreatic cancer.

Molecular Markers of Early Pancreatic Cancer

Pancreatic cancer is a deadly disease and the fourth most common cause of cancer death in the United States. Since chemotherapy and radiotherapy have thus far largely failed to significantly improve the survival of patients with pancreatic ductal adenocarcinoma, there is considerable interest in identifying better diagnostic markers of pancreatic neoplasia. Not only could better markers improve the early diagnosis of pancreatic cancer and allow more patients to undergo curative surgical resection, but also could potentially be used for patients at high risk of developing pancreatic cancer to identify precancerous lesions while they are amenable to cure. A wealth of information has recently become available about gene expression, DNA methylation, and proteomics alterations that occur in pancreatic cancers creating hope that better diagnostic markers of pancreatic cancer will be soon forthcoming.

Biliary brushing cytology

Biliary tract brush specimens are fast becoming the method of choice in the evaluation of patients who present with biliary tract strictures. Although the specificity is high, sensitivity rates for the detection of malignancy are generally low on cytological sampling. New liquid-based preparations and ancillary tests have emerged with the intent of addressing this issue. This review focuses on the current schemata used in the diagnosis of biliary tract lesions and the current available modalities which aid in the diagnosis of cholangiocarcinoma.

The role of preoperative biopsy in pancreatic cancer

BACKGROUND

Cyto-histological diagnosis of pancreatic pathology in the management of suspected pancreatic malignancy is re-evaluated in the light of evolving trends in management and tissue sampling.

METHODS

The literature on cyto-histological diagnosis of pancreatic pathology was reviewed over the period 1977-2003.

RESULTS AND CONCLUSION

Endoluminal techniques of tissue sampling carry less risk of tumour seeding and are the sampling methods of choice for potentially resectable lesions if a tissue diagnosis will alter therapy. Endosonar-guided biopsy in expert hands appears to be the most reliable tissue sampling technique. Transcoelomic sampling methods should be reserved for those with un-resectable disease. All methods of cyto-histological diagnosis have high specificity but have a low negative predictive value. Therefore, potentially resectable lesions that are highly suspicious for malignancy should be explored even if pre-operative histology or cytology is negative.

Novel markers of pancreatic adenocarcinoma in fine-needle aspiration: mesothelin and prostate stem cell antigen labeling increases accuracy in cytologically borderline cases

The interpretation of pancreas fine-needle aspiration (FNA) is extremely difficult given the cytologic overlap of neoplastic and reactive processes. Using serial analysis of gene expression, we have discovered 2 new markers of pancreatic adenocarcinoma, mesothelin and prostate stem cell antigen (PSCA), and confirmed their specificity by immunohistochemical labeling. Here we evaluate the potential contribution of immunohistochemical labeling of mesothelin and PSCA to the interpretation of pancreas FNAs. Thirty pancreas FNAs with follow-up data were reviewed. Unstained cell block sections from these aspirates labeled for mesothelin and PSCA using immunohistochemistry were compared with initial cytologic diagnoses and with follow-up diagnoses. On follow-up, 19 patients proved to have cancer, and 11 did not. Initial cytologic diagnosis of malignancy correlated with carcinoma on follow-up in 12 of 12 cases, and initial benign cytologic diagnosis correlated with benign follow-up in 8 of 9 cases (sensitivity, 92%; specificity, 100%). Six of the 9 patients with suspicious cytology were found to have a carcinoma on follow-up. PSCA labeling was present in 16 of the 19 patients who ultimately were proven to have carcinoma; PSCA labeling was absent in 10 of the 11 lesions proven to be benign (sensitivity, 84%; specificity, 91%). Mesothelin labeling was present in 13 of the 19 patients who ultimately were proven to have carcinoma; mesothelin labeling was absent in 10 of the 11 lesions proven to be benign (sensitivity, 68%; specificity, 91%). Five of the 6 cytologically suspicious cases with malignant follow-up labeled for either PSCA or mesothelin (83%), and 2 of the 6 cases labeled for both markers. None of the 3 suspicious cases with benign follow-up labeled for either PSCA or mesothelin. Increasingly, molecular techniques are identifying potential cancer markers that may have diagnostic utility. In this study, immunohistochemical labeling for 2 of these markers, PSCA and mesothelin, appears highly specific for pancreatic adenocarcinoma in FNA specimens and useful in categorizing cytologically suspicious lesions.

Cytologic diagnosis of adenocarcinoma in biliary and pancreatic duct brushings

Biliary and pancreatic duct brush specimens are relatively uncommon specimens seen by pathologists. Not only can the findings of malignancy be subtle, the implications of a malignant diagnosis can be significant. This review focuses on cholangiocarcinoma and pancreatic ductal adenocarcinoma sampled by endoscopic brush cytology, with an emphasis on diagnostic criteria for adenocarcinoma. In addition, assessment of specimen adequacy, utilization of liquid-based preparations, molecular diagnosis, and timing of liver transplantation in patients with primary sclerosing cholangitis are also briefly discussed.

Brush cytology of the biliary tract: retrospective study of 278 cases with histopathologic correlation

Bile aspiration during endoscopic retrograde cholangiopancreatography or percutaneous transhepatic cholangiography has been used as a diagnostic tool in the evaluations of pancreatic and biliary tree strictures for the last two decades. However, recently biliary tract brush cytology has become the method of choice in evaluating pancreatic/biliary tract abnormalities. The aim of this study was to evaluate the accuracy of pancreatobiliary lesions by an endobiliary cytotechnique. From 1993-1999, 278 pancreatobiliary brushings were performed at our institutions. Cytologic material was air-dried for Diff-Quik stain or fixed in ethanol for Papanicolaou staining. The cytologic diagnoses were classified in three categories: 1) benign, 2) atypical/suspicious, or 3) malignant. Subsequent surgical biopsy was available in 87 (31%) patients. There were 150 males and 128 females with a mean age of 63 yr (range 22-97); 167 (60%) were benign cases. Follow-up surgical material was available in 39 cases, seven of which showed adenocarcinoma; 67 of all cases (24%) were atypical/suspicious cases. Follow-up surgical material was available in 31 cases, 17 (55%) of which showed adenocarcinoma; 32 cases (12%) were malignant cases. Follow-up surgical material was available in 15 cases. All 15 cases were in agreement with the cytologic diagnosis. Twelve (4%) cases were unsatisfactory for cytologic examination. Follow-up surgical material was available in two cases. One case showed mucinous cystadenoma of the pancreas. The other case showed benign duct epithelium. Our study shows a sensitivity of 68% and a specificity of 100%. Of the atypical cases, 55% were malignant on follow-up biopsy. Brush cytology of pancreatobiliary strictures is the most widely used technique in the diagnosis of carcinoma, with a high degree of specificity.

K-ras, p53, and DPC4 (MAD4) alterations in fine-needle aspirates of the pancreas: a molecular panel correlates with and supplements cytologic diagnosis

Between January 1997 and February 2000, 101 fine-needle pancreatic aspirates were obtained. After a cytologic diagnosis was made, possible molecular alterations were determined on the 94 aspirates with adequate tissue using a molecular panel (K-ras, p53, and DPC4 [MAD4] genes). The 94 aspirates were categorized as follows: diagnostic of adenocarcinoma, 48 (51%); atypical (suggestive of but not diagnostic of adenocarcinoma), 19 (20%); negative for adenocarcinoma, 25 (2 7%); diagnostic of a neoplasm other than adenocarcinoma, 2 (2%). Clinical follow-up revealed that 3 patients (12%) with negative cytologic diagnoses and 12 patients (63%) with atypical cytologic diagnoses had adenocarcinoma. Of 63 with a final diagnosis of adenocarcinoma, 42 (67%) had an alteration in at least 1 of the genes analyzed. In contrast, only 2 (6%) of 31 patients without adenocarcinoma had an alteration in 1 gene on the panel. Overall, the molecular analyses supported the diagnosis of adenocarcinoma in 6 (32%) of 19 aspirates originally diagnosed as atypical by cytology alone. A molecular panel that includes the K-ras, p53, and DPC4 (MAD4) genes correlates with and can supplement traditional cytologic diagnosis of pancreatic fine-needle aspirates.

Pancreatic cancer after remote peptic ulcer surgery

BACKGROUND

Peptic ulcer surgery may carry an increased risk for pancreatic cancer development. Molecular analysis of K-ras codon 12, frequently mutated in conventional pancreatic cancers, might provide insight into the aetiological mechanisms.

METHODS

The relative risk of pancreatic cancer was computed by multivariate and person-year analysis in a cohort of 2633 patients who had undergone gastrectomy. Lung cancer risk was analysed as an indirect means of assessing smoking behaviour. K-ras codon 12 mutational analysis was performed on 15 postgastrectomy pancreatic cancers.

RESULTS

There was an overall increased risk of pancreatic carcinoma of 1.8 (95% confidence interval, 1.3 to 2.6) five to 59 years postoperatively, which gradually increased to 3.6 at 35 years or more after surgery (chi(2) test for trend, p < 0.05). Multivariate analysis indicated that parameters other than postoperative interval did not influence the risk. Lung cancer risk was significantly increased after surgery, but no time trend was observed. The spectrum and prevalence of K-ras codon 12 mutations were comparable to conventional pancreatic cancer.

CONCLUSIONS

Remote partial gastrectomy is associated with an increased risk of pancreatic cancer. Postgastrectomy and non-postgastrectomy pancreatic cancers may share similar aetiological factors, such as smoking. However, the neoplastic process in patients who have undergone gastrectomy appears to be accelerated by factors related to the surgery itself.

K-ras Point Mutation Detection in Lung Cancer: Comparison of Two Approaches to Somatic Mutation Detection Using ARMS Allele-specific Amplification

Background: The use of sensitive molecular techniques to detect rare cells in a population is of increasing interest to the molecular pathologist, but detection limits often are poorly defined in any given molecular assay. We combined the approaches of real-time quantitative PCR with ARMSTM allele-specific amplification in a novel assay for detecting mutant K-ras sequences in clinical samples.

Methods: ARMS reactions were used to detect seven commonly occurring mutations in the K-ras oncogene. These mutations produce amino acid changes in codon 12 (Gly to Ala, Arg, Asp, Cys, Ser, or Val) and codon 13 (Gly to Asp). A control reaction was used to measure the total amount of amplifiable K-ras sequence in a sample so that the ratio of mutant to wild-type sequence could be measured. Quantitative data were confirmed for a selection of samples by an independent cloning and sequencing method. The assay was used to analyze 82 lung tumor DNA samples.

Results: The assay detected K-ras mutations in 44% of adenocarcinomas, which is equivalent to frequencies reported in the literature using ultrasensitive techniques. Forty-six percent of squamous carcinomas were also positive. The ratio of mutant sequence in the tumor DNA samples was 0.04–100%.

Conclusions: The assay is homogeneous, with addition of tumor DNA sample being the only step before results are generated. The quantitative nature of the assay can potentially be used to define the analytical sensitivity necessary for any specified diagnostic application of K-ras (or other) point mutation detection.

Noninvasive and minimally invasive papillary carcinomas of the extrahepatic bile ducts

BACKGROUND

Adenocarcinomas of the extrahepatic bile ducts (EBD) are uncommon neoplasms that are morphologically heterogenous and associated with a poor prognosis. Papillary carcinomas of the EBD, however, appear to follow a much less aggressive clinical course.

METHODS

The authors reviewed the clinical records of nine patients with papillary carcinoma of the EBD, analyzed the microscopic features, and selected immunohistochemical reactivity (p53 and MIB-1) that might correlate with patient survival.

RESULTS

Six patients were male and three were female, with a mean age of 65 years (range, 48-83 years). The clinical presentation of disease in these patients was similar to that reported for conventional adenocarcinoma of EBD. According to their cell phenotypes, these papillary carcinomas were classified as biliary type (7 cases) and intestinal type (2 cases). Most were located in the common bile duct and were well differentiated (7 cases). Five showed minimal expansile invasion into the ductal wall and four were noninvasive. Five patients were treated with a Whipple operation, three underwent segmental resections, and one underwent a left hepatic lobectomy. One patient died of unrelated causes 16 years after a Whipple operation, and another died of postoperative complications. The remaining 7 patients are alive and disease free 1-13 years after surgery.

CONCLUSIONS

Noninvasive and minimally invasive papillary carcinomas of the EBD are associated with excellent long term prognosis regardless of their cytologic features or their immunohistochemical reactivity to p53 and MIB-1. These tumors should be distinguished from biliary papillomatosis, intraductal papillary mucinous carcinomas of the pancreas extending into the bile ducts, papillary adenomas, and papillary hyperplasia.

Ductal lesions in patients with chronic pancreatitis show K-ras mutations in a frequency similar to that in the normal pancreas and lack nuclear immunoreactivity for p53

BACKGROUND

Chronic pancreatitis (CP) is considered to be a risk factor for the development of pancreatic carcinoma. The detection of K-ras mutations in the duodenal or pancreatic juice has been held to be a reliable tool for its early diagnosis. However, K-ras mutations also occur in hyperplastic ductal epithelium, making it difficult to interpret their role in pancreatic carcinogenesis.

METHODS

The study included 30 resection specimens, 15 from patients with alcoholic CP, and 15 from patients with idiopathic CP. The mean duration of disease was 6.8 years. A total of 429 ductal lesions were classified according to the World Health Organization classification (1996) and microdissected. K-ras analysis was performed by means of polymerase chain reaction (45 cycles), constant denaturing gel electrophoresis, and sequencing. Immunostaining was performed with antibodies against p53, Ki-S5, carcinoembryonic antigen, and two types of mucins.

RESULTS

The 30 specimens demonstrated all types of ductal lesions. Severe cellular atypia was not observed. A total of 429 ductal lesions were analyzed. Approximately 4.4% of the lesions (19 of 429) from 27% of the patients (8 of 30) showed K-ras mutations, but they were unrelated to the duration or type of CP. Immunostaining for mutated p53 protein always was negative. Increased proliferative activity was noted only in patients with papillary hyperplasia. No patient developed pancreatic carcinoma within a follow-up period of at least 3 years.

CONCLUSIONS

Ductal lesions in patients with CP exhibit K-ras mutations without additional indications of neoplastic transformation such as severe dysplasia or mutated p53 protein. Therefore, for diagnostic and therapeutic purposes, the detection of K-ras mutations should be supplemented by the demonstration of additional genetic alterations or clinical signs of malignancy.

Screening for early pancreatic ductal adenocarcinoma in hereditary pancreatitis

Patients with hereditary pancreatitis have a 40% lifetime risk of developing pancreatic ductal adenocarcinoma. Existing methods of diagnosing pancreatic cancer such as tumor markers, endoscopy, and radiological imaging lack the sensitivity and specificity for early diagnosis, particularly in a background of chronic pancreatitis. Molecular based strategies offer new avenues of screening for pancreatic ductal adenocarcinoma in these high-risk patients, which may allow the development of highly sensitive and specific diagnostic tests for the early detection of cancer.

Diagnostic p53 immunostaining of endobiliary brush cytology: preoperative cytology compared with the surgical specimen

BACKGROUND

Endobiliary brush cytology is important in the distinction of malignant and benign causes of extrahepatic bile duct obstruction. The additional diagnostic value of p53 immunostaining on these cytology specimens was assessed.

METHODS

All patients with extrahepatic bile duct obstruction who underwent endoscopic retrograde cholangiopancreatography (ERCP) with endobiliary brush cytology and subsequent surgery at the Academic Medical Center in Amsterdam during a 3-year period were studied. p53 Immunocytology was compared with the corresponding conventional light microscopic cytology and p53 immunostaining of the subsequent surgical specimen.

RESULTS

Fifty-three patients with the following diagnoses were included: pancreatic carcinoma (23), bile duct carcinoma (15), ampullary carcinoma (5), lymph node metastases (2), carcinoma of unknown origin (4), chronic pancreatitis (3), and primary sclerosing cholangitis (1). Fifty-one percent of the carcinomas showed positive p53 immunostaining; all four surgical specimens without carcinoma were negative. The sensitivities of conventional light microscopic cytology, p53 immunocytology, and both tests combined were 29%, 24%, and 43%, respectively. These sensitivities were higher in cases of bile duct carcinoma (46%, 40%, and 66%) compared with cases of pancreatic carcinoma (13%, 9%, and 22%). Specificities of both tests were 100%.

CONCLUSIONS

p53 Immunostaining on endobiliary brush cytology may be helpful in the diagnosis of malignant extrahepatic bile duct stenosis, especially in patients with bile duct carcinoma. Cancer (Cancer Cytopathol)

Role of tumour markers, cytogenetics

A review is presented on the role of conventional and molecular tumour markers (TM) in diagnosis and monitoring of patients with biliopancreatic malignancies. For biliopancreatic malignancy, following CEA as more historical and basic TM of gastrointestinal diseases, the mainstay marker is CA 19-9 as monosialo-ganglioside/glycolipid and sialyl derivative of lacto-N-fucopentaose II (sialyl-Lewis(a), hapten of human Lewis(a) bloodgroup determinant). It is detected in serum of healthy individuals at low concentration < 40 U/ml, with lower and often transitional elevation in benign hepatobiliary diseases and with highest levels in excretory ductal pancreatic adenocarcinoma (s = 70%-95%, sp = 72%-90%), biliary (s = 55%-79%), hepatocellular and cholangiocellular cancer (s = 22%-51%) besides gastric, colorectal and ovarian cancer and occasionally in lung, breast and uterine cancer. Physiologically elevated concentrations in healthy individuals have to be considered in all sorts of secretions (e.g. sputum, saliva, bronchial/gastric secretions, bile juice) of individuals with Lewis(a)-positive secretor status in contrast with low or lacking serum levels of CA 19-9 in patients with Lewis(a-/b-) status (7%-10% of population). In biliopancreatic malignancies, especially pancreatic cancer, CA 19-9 correlates well with clinical course of disease following surgical, chemo- or radiotherapy by a quick normalisation within 2-4 weeks after complete surgery, a transient decrease with successful palliative therapy and an often anticipated increase (lead time up to 6 months) before clinical detection in case of relapse or progressive disease. From CA 19-9 related TM tests some are detecting in addition to sialyl-Lewis(a) (sialyllacto-N-fucopentaose II) also the non-fucosylated precursor sialyl-Lewis(c) (sialyllacto-N-tetraose: CA 50, CA 242, Span-1) solely detected by the DUPAN-2 test and independent of the Lewis(a) secretor status. Some other markers comprise in addition to sialyl-Lewis(a) partially the non-sialylated Lewis(a) antigen (CA 195, CAM 43, CA 494) or are less related (CAM 17.1). The initial phase of screening and early detection is hoped to be better assessed by using molecular markers detecting gene mutations (p53, K-ras), growth factors (EGF, TGF-alpha, TGF-beta, HB-EGF, a/bFGFs, KGF) and growth factor receptor alterations (EGFr, c-erbB2/3/4). From these, K-ras mutations detected in blood, stool and bile juice of patients at risk for pancreatic cancer seem to be more promising than p53 alterations as a more later step in carcinogenesis, although they are neither yet well established nor standardised by reliable assays. In contrast growth factor and growth factor receptor alterations mainly concerning signal transducing systems seem to reflect increased tumour aggressiveness, thus shorter survival and poorer prognosis thereby contributing in the selection of patients for more aggressive therapy.

Molecular genetics and related developments in pancreatic cancer

Cancer of the pancreas is a genetic disease. The most common genetic alterations identified to date in pancreatic cancer are activation of the K-ras oncogene (approximately 90%) and inactivation of the p16 (approximately 95%), p53 (50% to 75%), DPC4 (55%), and BRCA2 (7%) tumor suppressor genes. An understanding of the molecular genetics of carcinoma of the pancreas is important because it may help explain the aggregation of pancreatic cancer in families and may lead to the development of novel tests to detect early cancers. For example, the aggregation of pancreatic cancer in some families has been shown to result from inherited mutations in cancer-causing genes, and genetic alterations shed from pancreatic cancers have been detected in stool specimens. In addition, we believe that an improved knowledge of the molecular genetics of pancreatic cancer will lead to the development of a new generation of rational and more effective treatments.