PIK3CA mutations in intraductal papillary mucinous neoplasm/carcinoma of the pancreas

Systematic review of challenging issues in pathology of intraductal papillary mucinous neoplasms

BACKGROUND

Intraductal papillary mucinous neoplasms (IPMNs) are a cystic precursor to pancreatic cancer. IPMNs deemed clinically to be at high-risk for malignant progression are frequently treated with surgical resection, and pathological examination of the pancreatectomy specimen is a key component of the clinical care of IPMN patients.

METHODS

Systematic literature reviews were conducted around eight topics of clinical relevance in the examination of pathological specimens in patients undergoing resection of IPMN.

RESULTS

This review provides updated perspectives on morphological subtyping of IPMNs, classification of intraductal oncocytic papillary neoplasms, nomenclature for high-grade dysplasia, assessment of T stage, distinction of carcinoma associated or concomitant with IPMN, role of molecular assessment of IPMN tissue, role of intraoperative assessment by frozen section, and preoperative evaluation of cyst fluid cytology.

CONCLUSIONS

This analysis provides the foundation for data-driven approaches to several challenging issues in the pathology of IPMNs.

Synchronous manifestation of colorectal cancer and intraductal papillary mucinous neoplasms

High rates of extrapancreatic malignancies, in particular colorectal cancer (CRC), have been detected in patients with intraductal papillary mucinous neoplasm (IPMN). So far, there is no distinct explanation in the literature for the development of secondary or synchronous malignancies in patients with IPMN. In the past few years, some data related to common genetic alterations in IPMN and other affiliated cancers have been published. This review elucidated the association between IPMN and CRC, shedding light on the most relevant genetic alterations that may explain the possible relationship between these entities. In keeping with our findings, we suggested that once the diagnosis of IPMN is made, special consideration of CRC should be undertaken. Presently, there are no specific guidelines regarding colorectal screening programs for patients with IPMN. We recommend that patients with IPMNs are at high-risk for CRC, and a more rigorous colorectal surveillance program should be implemented.

Diagnostic accuracy of the AGA, IAP, and European guidelines for detecting advanced neoplasia in intraductal papillary mucinous neoplasm/neoplasia

BACKGROUND

Follow-up in patients with intraductal papillary mucinous neoplasm (IPMN) aims to detect advanced neoplasia (high-grade dysplasia/cancer) in an early stage. The 2015 American Gastroenterological Association (AGA), 2017 International Association of Pancreatology (IAP), and the 2018 European Study Group on Cystic tumours of the Pancreas (European) guidelines differ in their recommendations on indications for surgery. However, it remains unclear which guideline is most accurate in predicting advanced neoplasia in IPMN.

METHODS

Patients who underwent surgery were extracted from a prospective database (January 2006-January 2021). In patients with IPMN, final pathology was compared with the indication for surgery according to the guidelines. ROC-curves were calculated to determine the diagnostic accuracy for each guideline.

RESULTS

Overall, 247 patients underwent surgery for cystic lesions. In 145 patients with IPMN, 52 had advanced neoplasia, of which the AGA guideline would have advised surgery in 14 (27%), the IAP and European guideline in 49 (94%) and 50 (96%). In 93 patients without advanced neoplasia, the AGA, IAP, and European guidelines would incorrectly have advised surgery in 8 (8.6%), 77 (83%) and 71 (76%).

CONCLUSION

The European and IAP guidelines are clearly superior in detecting advanced neoplasia in IPMN as compared to the AGA, albeit at the cost of a higher rate of unnecessary surgery. To harmonize care and to avoid confusion caused by conflicting statements, a global evidence-based guideline for PCN in collaboration with the various guidelines groups is required once the current guidelines require an update.

Prospective, Multi-Institutional, Real-Time Next-Generation Sequencing of Pancreatic Cyst Fluid Reveals Diverse Genomic Alterations That Improve the Clinical Management of Pancreatic Cysts

BACKGROUND & AIMS

Next-generation sequencing (NGS) of pancreatic cyst fluid is a useful adjunct in the assessment of patients with pancreatic cyst. However, previous studies have been retrospective or single institutional experiences. The aim of this study was to prospectively evaluate NGS on a multi-institutional cohort of patients with pancreatic cyst in real time.

METHODS

The performance of a 22-gene NGS panel (PancreaSeq) was first retrospectively confirmed and then within a 2-year timeframe, PancreaSeq testing was prospectively used to evaluate endoscopic ultrasound-guided fine-needle aspiration pancreatic cyst fluid from 31 institutions. PancreaSeq results were correlated with endoscopic ultrasound findings, ancillary studies, current pancreatic cyst guidelines, follow-up, and expanded testing (Oncomine) of postoperative specimens.

RESULTS

Among 1933 PCs prospectively tested, 1887 (98%) specimens from 1832 patients were satisfactory for PancreaSeq testing. Follow-up was available for 1216 (66%) patients (median, 23 months). Based on 251 (21%) patients with surgical pathology, mitogen-activated protein kinase/GNAS mutations had 90% sensitivity and 100% specificity for a mucinous cyst (positive predictive value [PPV], 100%; negative predictive value [NPV], 77%). On exclusion of low-level variants, the combination of mitogen-activated protein kinase/GNAS and TP53/SMAD4/CTNNB1/mammalian target of rapamycin alterations had 88% sensitivity and 98% specificity for advanced neoplasia (PPV, 97%; NPV, 93%). Inclusion of cytopathologic evaluation to PancreaSeq testing improved the sensitivity to 93% and maintained a high specificity of 95% (PPV, 92%; NPV, 95%). In comparison, other modalities and current pancreatic cyst guidelines, such as the American Gastroenterology Association and International Association of Pancreatology/Fukuoka guidelines, show inferior diagnostic performance. The sensitivities and specificities of VHL and MEN1/loss of heterozygosity alterations were 71% and 100% for serous cystadenomas (PPV, 100%; NPV, 98%), and 68% and 98% for pancreatic neuroendocrine tumors (PPV, 85%; NPV, 95%), respectively. On follow-up, serous cystadenomas with TP53/TERT mutations exhibited interval growth, whereas pancreatic neuroendocrine tumors with loss of heterozygosity of ≥3 genes tended to have distant metastasis. None of the 965 patients who did not undergo surgery developed malignancy. Postoperative Oncomine testing identified mucinous cysts with BRAF fusions and ERBB2 amplification, and advanced neoplasia with CDKN2A alterations.

CONCLUSIONS

PancreaSeq was not only sensitive and specific for various pancreatic cyst types and advanced neoplasia arising from mucinous cysts, but also reveals the diversity of genomic alterations seen in pancreatic cysts and their clinical significance.

Pancreatic Cystic Lesions: A Focused Review on Cyst Clinicopathological Features and Advanced Diagnostics

Macroscopic, endomicroscopic, and histologic findings and correlation are an integral part of the diagnostic evaluation of pancreatic cystic lesions (PCLs), as complementing morphologic features seen by different specialties are combined to contribute to a final diagnosis. However, malignancy risk stratification of PCLs with worrisome features can still be challenging even after endoscopic ultrasound guided-fine needle aspiration (EUS-FNA) with cytological evaluation. This review aims to summarize cyst clinicopathological features from the pathologists' perspective, coupled with knowledge from advanced diagnostics-confocal laser endomicroscopy and cyst fluid molecular analysis, to demonstrate the state-of-art risk stratification of PCLs. This review includes illustrative photos of surgical specimens, endomicroscopic and histologic images, and a summary of cyst fluid molecular markers.

A pilot study to evaluate tissue- and plasma-based DNA driver mutations in a cohort of patients with pancreatic intraductal papillary mucinous neoplasms

Intraductal papillary mucinous neoplasms (IPMNs) are precursor lesions to pancreatic ductal adenocarcinoma that are challenging to manage due to limited imaging, cytologic, and molecular markers that accurately classify lesions, grade of dysplasia, or focus of invasion preoperatively. The objective of this pilot study was to determine the frequency and type of DNA mutations in a cohort of surgically resected, pathologically confirmed IPMN, and to determine if concordant mutations are detectable in paired pretreatment plasma samples. Formalin-fixed paraffin-embedded (FFPE) tissue from 46 surgically resected IPMNs (31 low-grade, 15 high-grade) and paired plasma from a subset of 15 IPMN cases (10 low-grade, 5 high-grade) were subjected to targeted mutation analysis using a QIAseq Targeted DNA Custom Panel. Common driver mutations were detected in FFPE from 44 of 46 (95.6%) IPMN cases spanning all grades; the most common DNA mutations included: KRAS (80%), RNF43 (24%), and GNAS (43%). Of note, we observed a significant increase in the frequency of RNF43 mutations from low-grade to high-grade IPMNs associated or concomitant with invasive carcinoma (trend test, P = 0.01). Among the subset of cases with paired plasma, driver mutations identified in the IPMNs were not detected in circulation. Overall, our results indicate that mutational burden for IPMNs is a common occurrence, even in low-grade IPMNs. Furthermore, although blood-based biopsies are an attractive, noninvasive method for detecting somatic DNA mutations, the QIAseq panel was not sensitive enough to detect driver mutations that existed in IPMN tissue using paired plasma in the volume we were able to retrieve for this retrospective study.

Integrating Molecular Analysis into the Pathologic Evaluation of Pancreatic Cysts

The development of cross-sectional imaging techniques has enhanced the detection of pancreatic cystic lesions (PCLs). PCLs are found in approximately 2% of the general population, often as incidentally detected lesions on computed tomography or MRI during the evaluation of other medical conditions. Broadly, PCLs are classified as mucinous or nonmucinous. Mucinous PCLs include mucinous cystic neoplasms and intraductal papillary mucinous neoplasms. Nonmucinous PCLs include pseudocysts, serous cystadenomas, solid pseudopapillary neoplasms, and cystic pancreatic neuroendocrine tumors, as well as cystic acinar cell carcinoma, cystic degeneration of pancreatic ductal adenocarcinoma, lymphoepithelial cyst, and others.

Invasive IPMN relapse later and more often in lungs in comparison to pancreatic ductal adenocarcinoma

BACKGROUND

The different oncological outcomes of invasive intraductal papillary mucinous neoplasm (I-IPMN) and pancreatic ductal adenocarcinoma (PDAC) are debated. This study aimed to compare disease recurrence patterns and histopathological characteristics in patients with resected I-IPMN and PDAC.

METHODS

Consecutive patients undergoing surgical resection for stage I-III I-IPMN or PDAC between 2010 and 2016 were retrospectively analyzed. Patients treated with neoadjuvant therapy or resected for Tis neoplasia were excluded. All surgical specimens were re-staged according to AJCC-8th-edition.

RESULTS

A total of 330 patients were included, of whom 43 had I-IPMN and 287 had PDAC. Median follow-up time was 26.7 (1.3-92.3) months and estimated median disease-free survival (DFS) was 60.3 months (47.2-73.4) for I-IPMN and 23.8 (19.3-28.2) months for PDAC (p < 0.001). During follow-up, 32.6% of I-IPMN and 67.9% of PDAC patients experienced recurrence (p < 0.001). The sites of first recurrence were the lungs (38.5% vs 13.1%, p = 0.027), liver (28.6% vs 45.0%, p = 0.180) and local (15.4% vs 36.6%, p = 0.101) for I-IPMN and PDAC, respectively. At multivariate analysis, I-IPMN histology remained an independent predictive factor for longer DFS (OR 0.528, CI 95% 0.278-1.000, p = 0.050), regardless of stage or adjuvant chemotherapy. I-IPMN and PDAC differed in rates of neuroinvasion (51.2% vs 97.2%) and positive lymph node status (N+) (46.5% vs 82.7%), especially in patients with lower T status.

CONCLUSION

I-IPMN showed a different recurrence pattern compared to PDAC, with a higher lung tropism, and longer DFS. This different biological behavior is associated with lower rates of neuroinvasion and nodal involvement, especially in early-stage disease.

The Natural Course of Pancreatic Cysts in Inflammatory Bowel Disease: Results of a Long-term Follow-up

OBJECTIVES

The natural course of pancreatic cysts in inflammatory bowel disease (IBD) is unknown. We aim to describe the natural course of pancreatic cysts in IBD and evaluate long-term outcomes.

METHODS

A database of patients with abdominal imaging diagnosis of pancreatic cysts (2008-2019) was reviewed. Patients with IBD and pancreatic cysts (study group) and pancreatic cysts without IBD (controls) were selected. Outcomes were measured at 1, 3, 5, and 10 years. Several logistic regression models were used for analysis.

RESULTS

Of the 1789 patients evaluated, 1690 had pancreatic cysts without IBD, and 78 had IBD and pancreatic cysts. Majority of cysts were intraductal papillary mucinous neoplasms. Patients with IBD and pancreatic cysts were more likely to be diagnosed with pancreatic cysts at a younger age (P < 0.001) and were more likely to undergo surgical intervention at a younger age (P < 0.001).

CONCLUSIONS

This is the first study to evaluate the natural course of pancreatic cysts in IBD patients. Patients with IBD were more likely to have pancreatic cysts detected at a younger age. Despite the early presentation, there were no differences in long-term outcomes. Patients with IBD with pancreatic cysts should be managed similarly to those without IBD.

Updates in the Diagnosis of Intraductal Neoplasms of the Pancreas

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest types of cancer worldwide. There are many reasons for this dismal prognosis, including the advanced stage at the time of diagnosis and the lack of effective therapeutic approaches. Intraductal papillary mucinous neoplasms (IPMNs) represent detectable and treatable precursor lesions of PDAC. Our understanding of the pathology of IPMNs has evolved over the past few decades, and new advances in diagnostic tools have emerged. The new World Health Organization (WHO) classification scheme now recognizes the previously considered variants of IPMNs, such as intraductal oncocytic papillary neoplasms (IOPNs) and intraductal tubulopapillary neoplasms (ITPNs), as distinct neoplasms. New imaging and molecular diagnostic tests are being developed to recognize these PDAC precursor lesions better. Here, we review the advances in diagnostic tools for IPMNs, IOPNs, and ITPNs, emphasizing the new (5th edition, 2019) WHO classification for pathological diagnosis, molecular markers, new laboratory tests, and imaging tools.

Pathology of intraductal papillary mucinous neoplasms

BACKGROUND

Intraductal papillary mucinous neoplasms (IPMNs) represent a unique opportunity to treat and prevent a curable neoplasm before it has the chance to progress to incurable cancer. This prospect, however, has to be balanced with the real risk of over treating patients with lesions that would, in fact, never progress during the life of the patient.

PURPOSE

Informed clinical decisions in the treatment of IPMNs are first and foremost based on a deep understanding of the pathology of these lesions.

CONCLUSIONS

Here we review the pathology of IPMNs, with an emphasis on the clinical relevance of the important features that characterize these lesions.

Biomarkers and Strategy to Detect Preinvasive and Early Pancreatic Cancer: State of the Field and the Impact of the EDRN

Patients afflicted with pancreatic ductal adenocarcinoma (PDAC) face a dismal prognosis, but headway could be made if physicians could identify the disease earlier. A compelling strategy to broaden the use of surveillance for PDAC is to incorporate molecular biomarkers in combination with clinical analysis and imaging tools. This article summarizes the components involved in accomplishing biomarker validation and an analysis of the requirements of molecular biomarkers for disease surveillance. We highlight the significance of consortia for this research and highlight resources and infrastructure of the Early Detection Research Network (EDRN). The EDRN brings together the multifaceted expertise and resources needed for biomarker validation, such as study design, clinical care, biospecimen collection and handling, molecular technologies, and biostatistical analysis, and studies coming out of the EDRN have yielded biomarkers that are moving forward in validation. We close the article with an overview of the current investigational biomarkers, an analysis of their performance relative to the established benchmarks, and an outlook on the current needs in the field. The outlook for improving the early detection of PDAC looks promising, and the pace of further research should be quickened through the resources and expertise of the EDRN and other consortia.See all articles in this CEBP Focus section, "NCI Early Detection Research Network: Making Cancer Detection Possible."

Non-coding RNA biomarkers in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignancies, which is usually diagnosed at an advanced stage. The late disease diagnosis, the limited availability of effective therapeutic interventions and lack of robust diagnostic biomarkers, are some of the primary reasons for the dismal 5-year survival rates (∼8%) in patients with PDAC. The pancreatic cancer develops through accumulation of a series of genomic and epigenomic alterations which lead to the transformation of normal pancreatic epithelium into an invasive carcinoma - a process that can take up to 15-20 years to develop, from the occurrence of first initiating mutational event. These facts highlight a unique window of opportunity for the earlier detection of PDAC, which could allow timely disease interception and improvement in the overall survival outcomes in patients suffering from this fatal malignancy. Non-coding RNAs (ncRNAs) have been recognized to play a central role in PDAC pathogenesis and are emerging as attractive candidates for biomarker development in various cancers, including PDAC. More specifically, the ncRNAs play a pivotal role in PDAC biology as they affect tumor growth, migration, and invasion by regulating cellular processes including cell cycle, apoptosis, and epithelial-mesenchymal transition. In this review, we focus on three types of well-established ncRNAs - microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs) - and discuss their potential as diagnostic, prognostic and predictive biomarkers in PDAC.

Genomic characterization of malignant progression in neoplastic pancreatic cysts

Intraductal papillary mucinous neoplasms (IPMNs) and mucinous cystic neoplasms (MCNs) are non-invasive neoplasms that are often observed in association with invasive pancreatic cancers, but their origins and evolutionary relationships are poorly understood. In this study, we analyze 148 samples from IPMNs, MCNs, and small associated invasive carcinomas from 18 patients using whole exome or targeted sequencing. Using evolutionary analyses, we establish that both IPMNs and MCNs are direct precursors to pancreatic cancer. Mutations in SMAD4 and TGFBR2 are frequently restricted to invasive carcinoma, while RNF43 alterations are largely in non-invasive lesions. Genomic analyses suggest an average window of over three years between the development of high-grade dysplasia and pancreatic cancer. Taken together, these data establish non-invasive IPMNs and MCNs as origins of invasive pancreatic cancer, identifying potential drivers of invasion, highlighting the complex clonal dynamics prior to malignant transformation, and providing opportunities for early detection and intervention.

Beyond the Genomic Mutation: Rethinking the Molecular Biomarkers of K-RAS Dependency in Pancreatic Cancers

Oncogenic v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (K-RAS) plays a key role in the development and maintenance of pancreatic ductal adenocarcinoma (PDAC). The targeting of K-RAS would be beneficial to treat tumors whose growth depends on active K-RAS. The analysis of K-RAS genomic mutations is a clinical routine; however, an emerging question is whether the mutational status is able to identify tumors effectively dependent on K-RAS for tailoring targeted therapies. With the emergence of novel K-RAS inhibitors in clinical settings, this question is relevant. Several studies support the notion that the K-RAS mutation is not a sufficient biomarker deciphering the effective dependency of the tumor. Transcriptomic and metabolomic profiles of tumors, while revealing K-RAS signaling complexity and K-RAS-driven molecular pathways crucial for PDAC growth, are opening the opportunity to specifically identify K-RAS-dependent- or K-RAS-independent tumor subtypes by using novel molecular biomarkers. This would help tumor selection aimed at tailoring therapies against K-RAS. In this review, we will present studies about how the K-RAS mutation can also be interpreted in a state of K-RAS dependency, for which it is possible to identify specific K-RAS-driven molecular biomarkers in certain PDAC subtypes, beyond the genomic K-RAS mutational status.

Macropinocytosis Renders a Subset of Pancreatic Tumor Cells Resistant to mTOR Inhibition

Pancreatic ductal adenocarcinoma (PDAC) features a near-universal mutation in KRAS. Additionally, the tumor suppressor PTEN is lost in ∼10% of patients, and in mouse models, this dramatically accelerates tumor progression. While oncogenic KRAS and phosphatidylinositol 3-kinase (PI3K) cause divergent metabolic phenotypes individually, how they synergize to promote tumor metabolic alterations and dependencies remains unknown. We show that in KRAS-driven murine PDAC cells, loss of Pten strongly enhances both mTOR signaling and macropinocytosis. Protein scavenging alleviates sensitivity to mTOR inhibition by rescuing AKT phosphorylation at serine 473 and consequently cell proliferation. Combined inhibition of mTOR and lysosomal processing of internalized protein eliminates the macropinocytosis-mediated resistance. Our results indicate that mTORC2, rather than mTORC1, is an important regulator of protein scavenging and that protein-mediated resistance could explain the lack of effectiveness of mTOR inhibitors in certain genetic backgrounds. Concurrent inhibition of mTOR and protein scavenging might be a valuable therapeutic approach.

Diagnosis and management of pancreatic cystic neoplasms: current evidence and guidelines

Pancreatic cystic neoplasms (PCN) are a heterogeneous group of pancreatic cysts that include intraductal papillary mucinous neoplasms, mucinous cystic neoplasms, serous cystic neoplasms and other rare cystic lesions, all with different biological behaviours and variable risk of progression to malignancy. As more pancreatic cysts are incidentally discovered on routine cross-sectional imaging, optimal surveillance for patients with PCN is becoming an increasingly common clinical problem, highlighting the need to balance cancer prevention with the risk of (surgical) overtreatment. This Review summarizes the latest developments in the diagnosis and management of PCN, including the quality of available evidence. Also discussed are the most important differences between the PCN guidelines from the American Gastroenterological Association, the International Association of Pancreatology and the European Study Group on Cystic Tumours of the Pancreas, including diagnostic and follow-up strategies and indications for surgery. Finally, new developments in the management of patients with PCN are addressed.

From somatic mutation to early detection: insights from molecular characterization of pancreatic cancer precursor lesions

Pancreatic cancer arises from noninvasive precursor lesions, including pancreatic intraepithelial neoplasia (PanIN), intraductal papillary mucinous neoplasm (IPMN), and mucinous cystic neoplasm (MCN), which are curable if detected early enough. Recently, these types of precursor lesions have been extensively characterized at the molecular level, defining the timing of critical genetic alterations in tumorigenesis pathways. The results of these studies deepen our understanding of tumorigenesis in the pancreas, providing novel insights into tumor initiation and progression. Perhaps more importantly, they also provide a rational foundation for early detection approaches that could allow clinical intervention prior to malignant transformation. In this review, we summarize the results of comprehensive molecular characterization of PanINs, IPMNs, and MCNs and discuss the implications for cancer biology as well as early detection. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Epidermal growth factor receptor (EGFR) gene alteration and protein overexpression in Malaysian triple-negative breast cancer (TNBC) cohort

Background

Epidermal growth factor receptor (EGFR) is a member of the ErbB family of tyrosine kinase receptor proteins that plays important roles in tumour cell survival and proliferation. EGFR has been reported to be overexpressed in up to 78% of triple-negative breast cancer (TNBC) cases suggesting it as a potential therapeutic target. The clinical trials of anti-EGFR agents in breast cancer showed low response rates. However, a subgroup of patients demonstrated response to EGFR inhibitors highlighting the necessity to stratify patients, who might benefit from effective combination therapy that could include anti EGFR-agents. Population variability in EGFR expression warrants systematic evaluation in specific populations.

Purpose

To study EGFR alterations and expressions in a multi ethnic Malaysian TNBC patient cohort to determine the possibility of using anti-EGFR combinatorial therapy for this population.

Patients and methods

In this study, we evaluated 58 cases of Malaysian TNBC patient samples for EGFR gene copy number alteration and EGFR protein overexpression using fluorescence in-situ hybridization (FISH) and immunohistochemistry (IHC) methods, respectively.

Results

EGFR protein overexpression was observed in about 30% while 15.5% displayed high EGFR copy number including 5.17% gene amplification and over 10% high polysomy. There is a positive correlation between EGFR protein overexpression and gene copy number and over expression of EGFR is observed in ten out of the 48 low copy number cases (20.9%) without gene amplification.

Conclusion

This study provides the first glimpse of EGFR alterations and expressions in a multi ethnic Malaysian TNBC patient cohort emphasising the need for the nationwide large scale EGFR expression evaluation in Malaysia.

Intraductal oncocytic papillary neoplasm of the pancreas: A systematic review

BACKGROUND

Intraductal oncocytic papillary neoplasm of the pancreas (IOPN-P) is a rare subtype of intraductal papillary mucinous neoplasm (IPMN). This study was performed to summarize the clinicopathological features and management of IOPN-P.

METHODS

English-language articles were searched from MEDLINE and EMBASE from the first report of IOPN-P in 1996 until 1 May 2019 following the methodology in the PRISMA guidelines.

RESULTS

In total, 66 patients from 24 full articles were included in the final data analysis. The patients' average age was 61 years, and the male/female ratio was 1. Most lesions were large (average size, 5.50 cm), located in the pancreatic head, and found either incidentally or by uncharacteristic abdominal symptoms. IOPN-P was usually a cystic and solid lesion with or without mural nodules on radiological examination. A definitive diagnosis was often acquired from fine needle aspiration biopsy or postoperative pathology. All tumors were diagnosed as carcinoma in situ or minimally invasive carcinoma, necessitating surgical resection. The prognosis of IOPN-P was better than that of other IPMN subtypes, even when metastasis occurred. Recurrence after surgical resection of IOPN-P was rare.

CONCLUSIONS

IOPN-P is rare among IPMN subtypes with unique pathological characteristics. Because of the nontypical symptoms and radiological findings, a definitive preoperative diagnosis usually depends on multimodal examinations. Management and surveillance of IOPN-P after surgical resection should be differentiated from those of other pancreatic benign cystic lesions because of its relative malignancy, but IOPN-P should also be differentiated from other IPMN subtypes and malignant cystic tumors because of its favorable prognosis.

Increased Risk of Second Primary Cancers Following Diagnosis of Malignant Intraductal Papillary Mucinous Neoplasms of the Pancreas: A Population-Based Study

Introduction: Several studies have reported that intraductal papillary mucinous neoplasms (IPMNs) of the pancreas are associated with extra-pancreatic malignancies. However, there have been no population-based studies evaluating the risk of second primary cancers (SPCs) in patients with pancreatic IPMN.

Methods: The Surveillance, Epidemiology, and End Results (SEER) database was used to identify and characterize data from patients with IPMN of the pancreas. The standard incidence ratio (SIR) of this cancer was calculated by estimating the relative risk (RR). A multivariate Cox regression model was used to estimate hazards ratios (HRs) of death and associated 95% CIs.

Results: Of 2,850 patients with IPMN of the pancreas, 104 patients (3.65%) developed 118 SPCs. The SIR for all SPCs combined was 1.22 (95% confidence interval [CI] = 1.01–1.46; P < 0.05). There was an elevated risk of site-specific SPCs in the small intestine (SIR = 8.68; 95% CI = 2.36–22.22), pancreas (SIR = 2.66; 95% CI = 1.15–5.25), urinary bladder (SIR = 2.02; 95% CI = 1.05–3.54), and eye and orbit (SIR = 13.47; 95% CI = 1.63–48.67) in patients with pancreas IPMN. In age subgrouping, people aged younger than 50 years had an increased risk of all-site SPC with an SIR of 6.44 (95% CI = 2.78–12.68). Cox regression modeling showed that advanced disease stage and a short latency period carried a higher risk of death in IPMN patients with SPC.

Conclusions: Patients diagnosed with pancreatic IPMNs were at higher risk than the general population for developing a second primary malignancy. Meanwhile, advanced historic stage and short latency period were associated with an elevated HR in IPMN patients who develop an SPC.

Advanced diagnostics for pancreatic cysts: Confocal endomicroscopy and molecular analysis

Technological advances and the widespread use of medical imaging have led to an increase in the identification of pancreatic cysts in patients who undergo cross-sectional imaging. Current methods for the diagnosis and risk-stratification of pancreatic cysts are suboptimal, resulting in both unnecessary surgical resection and overlooked cases of neoplasia. Accurate diagnosis is crucial for guiding how a pancreatic cyst is managed, whether with surveillance for low-risk lesions or surgical resection for high-risk lesions. This review aims to summarize the current literature on confocal endomicroscopy and cyst fluid molecular analysis for the evaluation of pancreatic cysts. These recent technologies are promising adjuncts to existing approaches with the potential to improve diagnostic accuracy and ultimately patient outcomes.

Real-Time Targeted Genome Profile Analysis of Pancreatic Ductal Adenocarcinomas Identifies Genetic Alterations That Might Be Targeted With Existing Drugs or Used as Biomarkers

BACKGROUND & AIMS

It has been a challenge to select treatment for patients with pancreatic ductal adenocarcinomas (PDACs) based on genome alterations. We performed targeted genomic profile analyses of a large number of PDACs to assess the full spectrum of actionable genomic alterations.

METHODS

We performed targeted genomic profile analyses of 3594 PDAC samples from an international cohort, including capture-based targeted genomic profiling of as many as 315 cancer-associated genes and intron regions of 28 genes that are rearranged in cancer cells. Tumor mutation burden (TMB) and microsatellite instability (MSI) status were also assessed. TMB was calculated across a 1.14-megabase region; TMB-high was defined as ≥20 mutations/megabase. MSI-high status was assigned based on analysis of 114 intron homopolymer loci.

RESULTS

KRAS, TP53, CDKN2A, and SMAD4 were the most frequently altered genes in PDAC. We found KRAS mutations in 88% of samples. Among PDACs without mutations in KRAS, we found alterations in genes whose products are in the mitogen-activated protein kinase signaling pathway and are candidate drug targets (actionable targets, n = 132; 4%), as well as gene fusions (n = 51), gene amplifications (n = 35), genes with missense mutations (n = 30), and genes that contain deletions (n = 16). Many of these encode proteins in receptor tyrosine kinase, RAS, or mitogen-activated protein kinase signaling pathways. Aside from TP53, alterations in genes encoding DNA damage repair proteins (BRCA and FANC) were detected in 14% of PDACs. Among PDACs evaluated for MSI (n = 2563) and TMB (n = 1021), MSI-high and/or TMB-high phenotypes were detected in 0.5% of samples. Alterations in FGF23, CCND2, PIK3CA, and FGF6 were more commonly detected in intraductal papillary mucinous neoplasm-associated PDACs.

CONCLUSIONS

In targeted genomic profile analyses of 3594 PDACs, we found 17% to contain genomic alterations that might make the tumor cells susceptible to currently used anticancer agents. We identified mutations in genes that could contribute to progression of intraductal papillary mucinous neoplasms into malignancies. These alterations might be used as biomarkers for early detection.

Genetics of Familial and Sporadic Pancreatic Cancer

In the previous decade, comprehensive genomic analyses have yielded important insights about the genetic alterations that underlie pancreatic tumorigenesis. Whole-exome and whole-genome sequencing of pancreatic ductal adenocarcinomas have confirmed the critical driver genes altered in the majority of pancreatic cancers, as well as identified numerous less frequently altered driver genes, and have delineated cancer subgroups with unique biological and clinical features. It is now appreciated that pancreatic susceptibility gene alterations are often identified in patients with pancreatic cancer without family histories suggestive of a familial cancer syndrome, prompting recent efforts to expand gene testing to all patients with pancreatic cancer. Studies of pancreatic cancer precursor lesions have begun to elucidate the evolutionary history of pancreatic tumorigenesis and to help us understand the utility of biomarkers for early detection and targets to develop new therapeutic strategies. In this review, we discuss the results of comprehensive genomic characterization of pancreatic ductal adenocarcinoma and its precursor lesions, and we highlight translational applications in early detection and therapy.

Early Detection of Pancreatic Cancer: Opportunities and Challenges

Most patients with pancreatic ductal adenocarcinoma (PDAC) present with symptomatic, surgically unresectable disease. Although the goal of early detection of PDAC is laudable and likely to result in significant improvement in overall survival, the relatively low prevalence of PDAC renders general population screening infeasible. The challenges of early detection include identification of at-risk individuals in the general population who would benefit from longitudinal surveillance programs and appropriate biomarker and imaging-based modalities used for PDAC surveillance in such cohorts. In recent years, various subgroups at higher-than-average risk for PDAC have been identified, including those with familial risk due to germline mutations, a history of pancreatitis, patients with mucinous pancreatic cysts, and elderly patients with new-onset diabetes. The last 2 categories are discussed at length in terms of the opportunities and challenges they present for PDAC early detection. We also discuss current and emerging imaging modalities that are critical to identifying early, potentially curable PDAC in high-risk cohorts on surveillance.

High Frequency of ERBB2 Activating Mutations in Invasive Lobular Breast Carcinoma with Pleomorphic Features

Background: Characterisation of molecular alterations of pleomorphic lobular carcinoma (PLC), an aggressive subtype of invasive lobular carcinoma (ILC), have not been yet completely accomplished. Methods: To investigate the molecular alterations of invasive lobular carcinoma with pleomorphic features, a total of 39 tumour samples (in situ and invasive lesions and lymph node metastases) from 27 patients with nuclear grade 3 invasive lobular carcinomas were subjected to morphological, immunohistochemical and massive parallel sequencing analyses. Results: Our observations indicated that invasive lobular carcinomas with pleomorphic features were morphologically and molecularly heterogeneous. All cases showed absence or aberrant expression of E-cadherin and abnormal expression of β-catenin and p120. CDH1 (89%), PIK3CA (33%) and ERRB2 (26%) were the most common mutated genes. ERBB2 mutations preferentially affected the tyrosine-kinase activity domain, being the most frequent the targetable mutation p.L755S (57%). We also observed higher frequency of mutations in ARID1B, KMT2C, MAP3K1, TP53 and ARID1A in PLC than previously reported in classic ILC. Alterations related to progression from in situ to invasive carcinoma and/or to lymph node metastases included TP53 mutation, amplification of PIK3CA and CCND1 and loss of ARID1A expression. Conclusions: The high frequency of ERBB2 mutations observed suggests that ERBB2 mutation testing should be considered in all invasive lobular carcinomas with nuclear grade 3.

Preoperative next-generation sequencing of pancreatic cyst fluid is highly accurate in cyst classification and detection of advanced neoplasia

OBJECTIVE

DNA-based testing of pancreatic cyst fluid (PCF) is a useful adjunct to the evaluation of pancreatic cysts (PCs). Mutations in KRAS/GNAS are highly specific for intraductal papillary mucinous neoplasms (IPMNs) and mucinous cystic neoplasms (MCNs), while TP53/PIK3CA/PTEN alterations are associated with advanced neoplasia. A prospective study was performed to evaluate preoperative PCF DNA testing.

DESIGN

Over 43-months, 626 PCF specimens from 595 patients were obtained by endoscopic ultrasound (EUS)-fine needle aspiration and assessed by targeted next-generation sequencing (NGS). Molecular results were correlated with EUS findings, ancillary studies and follow-up. A separate cohort of 159 PCF specimens was also evaluated for KRAS/GNAS mutations by Sanger sequencing.

RESULTS

KRAS/GNAS mutations were identified in 308 (49%) PCs, while alterations in TP53/PIK3CA/PTEN were present in 35 (6%) cases. Based on 102 (17%) patients with surgical follow-up, KRAS/GNAS mutations were detected in 56 (100%) IPMNs and 3 (30%) MCNs, and associated with 89% sensitivity and 100% specificity for a mucinous PC. In comparison, KRAS/GNAS mutations by Sanger sequencing had a 65% sensitivity and 100% specificity. By NGS, the combination of KRAS/GNAS mutations and alterations in TP53/PIK3CA/PTEN had an 89% sensitivity and 100% specificity for advanced neoplasia. Ductal dilatation, a mural nodule and malignant cytopathology had lower sensitivities (42%, 32% and 32%, respectively) and specificities (74%, 94% and 98%, respectively).

CONCLUSIONS

In contrast to Sanger sequencing, preoperative NGS of PCF for KRAS/GNAS mutations is highly sensitive for IPMNs and specific for mucinous PCs. In addition, the combination of TP53/PIK3CA/PTEN alterations is a useful preoperative marker for advanced neoplasia.

Next generation sequencing of the cellular and liquid fraction of pancreatic cyst fluid supports discrimination of IPMN from pseudocysts and reveals cases with multiple mutated driver clones: First findings from the prospective ZYSTEUS biomarker study

Approximately half of all pancreatic cysts are neoplastic, mainly comprising intraductal papillary mucinous neoplasms (IPMN), which can progress to invasive carcinoma. Current Fukuoka guidelines have limited sensitivity and specificity in predicting progression of asymptomatic pancreatic cysts. We present first results of the prospective ZYSTEUS biomarker study investigating (i) whether detection of driver mutations in IPMN by liquid biopsy is technically feasible, (ii) which compartment of IPMN is most suitable for analysis, and (iii) implications for clinical diagnostics. Twenty-two patients with clinical inclusion criteria were enrolled in ZYSTEUS. Fifteen cases underwent endoscopic ultrasound (EUS)-guided fine-needle aspiration and cytological diagnostics. Cellular and liquid fraction of the cysts of each case were separated and subjected to deep targeted next generation sequencing (NGS). Clinical parameters, imaging findings (EUS and MRI), and follow-up data were collected continuously. All IPMN cases (n = 12) showed at least one mutation in either KRAS (n = 11) or GNAS (n = 4). Three cases showed both KRAS and GNAS mutations. Six cases harbored multiple KRAS/GNAS mutations. In the three cases with pseudocysts, no KRAS or GNAS mutations were detected. DNA yields were higher and showed higher mutation diversity in the cellular fraction. In conclusion, mutation detection in pancreatic cyst fluid is technically feasible with more robust results in the cellular than in the liquid fraction. Current results suggest that, together with imaging, targeted sequencing supports discrimination of IPMN from pseudocysts. The prospective design of ZYSTEUS will provide insight into diagnostic value of NGS in preoperative risk stratification. Our data provide evidence for an oligoclonal nature of IPMN.

Genetic Alterations of Periampullary and Pancreatic Ductal Adenocarcinoma: An Overview

Pancreatic Ductal AdenoCarcinoma (PDAC) is one of the most lethal malignancies of all solid cancers. Precancerous lesions for PDAC include PanIN, IPMNs and MCNs. PDAC has a poor prognosis with a 5-year survival of approximately 6%. Whereas Periampulary AdenoCarcinoma (PAC) having four anatomic subtypes, pancreatic, Common Bile Duct (CBD), ampullary and duodenum shows relative better prognosis. The highest incidence of PDAC has been reported with black with respect to white population. Similarly, incidence rate of PAC also differs with different ethnic populations. Several lifestyle, environmental and occupational exposures including long-term diabetes, obesity, and smoking, have been linked to PDAC, however, for PAC the causal risk factors were poorly described. It is now clear that PDAC and PAC are a multi-stage process resulting from the accumulation of genomic alterations in the somatic DNA of normal cells as well as inherited mutations. Approximately 10% of PDAC have a familial inheritance. Germline mutations in CDKN2A, BRCA2, STK11, PALB2, PRSS1, etc., as well as certain syndromes have been well associated with predisposition to PDAC. KRAS, CDKN2A, TP53 and SMAD4 are the 4 "mountains" (high-frequency driver genes) which have been known to earliest somatic alterations for PDAC while relatively less frequent in PAC. Our understanding of the molecular carcinogenesis has improved in the last few years due to extensive research on PDAC which was not well explored in case of PAC. The genetic alterations that have been identified in PDAC and different subgroups of PAC are important implications for the development of genetic screening test, early diagnosis, and prognostic genetic markers. The present review will provide a brief overview of the incidence and prevalence of PDAC and PAC, mainly, increased risk in India, the several kinds of risk factors associated with the diseases as well as required genetic alterations for disease initiation and progression.

Study on PIK3CA Gene Mutations in Oral Squamous Cell Carcinoma among South Indian populations

The present investigation was performed in South Indian Populations to determine the hotspot mutation frequency in Oral Squamous Cell Carcinoma (OSCC) patients with PIK3CA gene Exon 9 and Exon 20 and its correlations with help of their clinical characteristics leading to these mutations. PI3KCA belongs to a group of regulatory heterodimeric lipid kinase which is involved in proliferation of cells, apoptosis and as well in metastasis which is controlled by PIK3CA gene is subjected to high frequency of somatic mutation in various tumors including OSCC. Total of 25 OSCC patients samples comprising of male and female subjects from Government tertiary care Centre were included in this study. Tumor specimen samples were collected and amplified for PIK3CA gene by PCR and subjected to genomic DNA Sequencing. Our findings showed total of 20% of oncogenic frequency in PIK3CA gene. We also observed two hot spot mutations (E545K) in exon 9 gene and three hot spot mutations (H1047Q, H1047Y, H1048Q) in exon 20 gene in our study populations. 0 Based on our findings it may be concluded that PIK3CA gene Exon 9 and Exon 20 contributes to a major role in pathogenesis on OSCC among South Indian populations may act as therapeutic target for a anticancer drug for the treatment OSCC.

Cyst Fluid Biomarkers - Diagnosis and Prediction of Malignancy for Cystic Lesions of the Pancreas

Pancreatic cysts are common, and are identified in 2-13% of individuals undergoing cross-sectional imaging. Intraductal papillary mucinous neoplasms (IPMNs) and mucinous cystic neoplasms (MCNs) are pancreatic cysts which are precursors to pancreatic adenocarcinoma. Currently available tools are imperfect at differentiating IPMNs and MCNs from other, benign types of pancreatic cysts. The role of molecular markers in the evaluation of pancreatic cysts and the identification of cysts with high-grade dysplasia or invasive adenocarcinoma is reviewed.

Intraductal papillary mucinous neoplasms of the pancreas: Clinical association with KRAS

Intraductal papillary mucinous neoplasms of the pancreas (IPMN) are among the most important precancerous lesions in the pancreas. V‑Ki‑ras 2 Kirsten rat sarcoma viral oncogene homolog (KRAS) is one of the most important genes involved in pancreatic neoplasms, and exhibits a high mutation rate in pancreatic ductal adenocarcinomas and pancreatic intraepithelial neoplasia. The present study aimed to further elucidate the associations among IPMN subtypes (gastric, intestinal, pancreatobiliary and oncocytic), pathological classifications [low‑grade, intermediate‑grade, and high‑grade IPMN, and associated minimally invasive carcinoma (invasive depth ≤0.5 cm) and advanced invasive carcinoma (invasive depth >0.5 cm)]. A total of 56 cases of IPMN were studied using scorpion amplified refractory mutation system analysis of KRAS mutations, pathological features and prognosis. KRAS mutations were identified in 50% (28/56 cases). The frequency was 60% (9/15 cases) in gastric‑type, 52.6% (10/19 cases) in intestinal‑type, 47.3% (9/19 cases) in pancreatobiliary‑type and zero (0/3 cases) in oncocytic‑type IPMN. Except for oncocytic type IPMN, the frequencies of KRAS mutations in IPMN with low, intermediate and high grade, and IPMN‑associated carcinoma were 58.3% (7/12 cases), 27.3% (3/11 cases), 80% (4/5 cases) and 56% (14/25 cases), respectively. With more advanced dysplasia and invasion, the prevalence of KRAS mutations in intestinal‑type IPMN increased (P=0.012). The Kaplan‑Meier survival curve demonstrated that survival rate was not associated with KRAS mutation (log‑rank test; P=0.308). The prevalence of KRAS mutations was lowest in intestinal‑type IPMN, and was in proportion to the degree of dysplasia and invasion. Therefore, KRAS mutation in IPMN does not correlate with histological subtype, dysplasia grade, depth of invasion or survival.

Phosphoinositide 3-Kinase Signaling Pathway in Pancreatic Ductal Adenocarcinoma Progression, Pathogenesis, and Therapeutics

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive malignancy characterized by its sudden manifestation, rapid progression, poor prognosis, and limited therapeutic options. Genetic alterations in key signaling pathways found in early pancreatic lesions are pivotal for the development and progression of pancreatic intraepithelial neoplastic lesions into invasive carcinomas. More than 90% of PDAC tumors harbor driver mutations in K-Ras that activate various downstream effector-signaling pathways, including the phosphoinositide-3-kinase (PI3K) pathway. The PI3K pathway also responds to stimuli from various growth factor receptors present on the cancer cell surface that, in turn, modulate downstream signaling cascades. Thus, the inositide signaling acts as a central node in the complex cellular signaling networks to impact cancer cell growth, motility, metabolism, and survival. Also, recent publications highlight the importance of PI3K signaling in stromal cells, whereby PI3K signaling modifies the tumor microenvironment to dictate disease outcome. The high incidence of mutations in the PI3K signaling cascade, accompanied by activation of parallel signaling pathways, makes PI3K a promising candidate for drug therapy. In this review, we describe the role of PI3K signaling in pancreatic cancer development and progression. We also discuss the crosstalk between PI3K and other major cellular signaling cascades, and potential therapeutic opportunities for targeting pancreatic ductal adenocarcinoma.

Loss of Pten and Activation of Kras Synergistically Induce Formation of Intraductal Papillary Mucinous Neoplasia From Pancreatic Ductal Cells in Mice

BACKGROUND & AIMS

Intraductal papillary mucinous neoplasias (IPMNs) are precancerous cystic lesions that can develop into pancreatic ductal adenocarcinomas (PDACs). These large macroscopic lesions are frequently detected during medical imaging, but it is unclear how they form or progress to PDAC. We aimed to identify cells that form IPMNs and mutations that promote IPMN development and progression.

METHODS

We generated mice with disruption of Pten specifically in ductal cells (Sox9CreER^T2;Pten^flox/flox;R26R^YFP or Pten^{ΔDuct/ΔDuct} mice) and used Pten^ΔDuct/+ and Pten^+/+ mice as controls. We also generated Kras^G12D;Pten^{ΔDuct/ΔDuct} and Kras^G12D;Pten^ΔDuct/+ mice. Pancreata were collected when mice were 28 weeks to 14.5 months old and analyzed by histology, immunohistochemistry, and electron microscopy. We performed multiplexed droplet digital polymerase chain reaction to detect spontaneous Kras mutations in Pten^{ΔDuct/ΔDuct} mice and study the effects of Ras pathway activation on initiation and progression of IPMNs. We obtained 2 pancreatic sections from a patient with an invasive pancreatobiliary IPMN and analyzed the regions with and without the invasive IPMN (control tissue) by immunohistochemistry.

RESULTS

Mice with ductal cell-specific disruption of Pten but not control mice developed sporadic, macroscopic, intraductal papillary lesions with histologic and molecular features of human IPMNs. Pten^{ΔDuct/ΔDuct} mice developed IPMNs of several subtypes. In Pten^{ΔDuct/ΔDuct} mice, 31.5% of IPMNs became invasive; invasion was associated with spontaneous mutations in Kras. Kras^G12D;Pten^{ΔDuct/ΔDuct} mice all developed invasive IPMNs within 1 month. In Kras^G12D;Pten^ΔDuct/+ mice, 70% developed IPMN, predominately of the pancreatobiliary subtype, and 63.3% developed PDAC. In all models, IPMNs and PDAC expressed the duct-specific lineage tracing marker yellow fluorescent protein. In immunohistochemical analyses, we found that the invasive human pancreatobiliary IPMN tissue had lower levels of PTEN and increased levels of phosphorylated (activated) ERK compared with healthy pancreatic tissue.

CONCLUSIONS

In analyses of mice with ductal cell-specific disruption of Pten, with or without activated Kras, we found evidence for a ductal cell origin of IPMNs. We also showed that PTEN loss and activated Kras have synergistic effects in promoting development of IPMN and progression to PDAC.

Confocal endomicroscopy and cyst fluid molecular analysis: Comprehensive evaluation of pancreatic cysts

Increases in the quality as well as utilization of cross-sectional imaging have led to rising diagnoses of pancreatic cystic lesions (PCL). Accurate presurgical diagnosis enables appropriate triage of PCLs. Unfortunately, current diagnostic approaches have suboptimal accuracy and may lead to unnecessary surgical resections or missed diagnoses of advanced neoplasia. Additionally, early detection represents an opportunity for intervention to prevent the progression to pancreatic adenocarcinoma. Our aim for this review is to systematically review the current literature on confocal endomicroscopy and molecular biomarkers in the evaluation of PCLs. Confocal laser endomicroscopy is a novel technology that allows for real-time in vivo microscopic imaging with multiple clinical trials identifying characteristic endomicroscopy findings of various pancreatic cystic lesions. DNA-based molecular markers have also emerged as another diagnostic modality as the pattern of genetic alternations present in cyst fluid can provide both diagnostic and prognostic data. We propose that both techniques can be utilized to improve patient outcomes.

Classification, Morphology, Molecular Pathogenesis, and Outcome of Premalignant Lesions of the Pancreas

CONTEXT

- Invasive pancreatic ductal adenocarcinoma has a greater than 90% mortality rate at 5 years. Understanding noninvasive, curable precursor lesions gives us the best hope for reducing mortality from pancreatic ductal adenocarcinoma. The 3 pancreatic precursor lesions that have been well studied include intraductal papillary mucinous neoplasm, mucinous cystic neoplasm, and pancreatic intraepithelial neoplasia.

OBJECTIVE

- To give an update on the latest clinical, molecular, and pathologic advances in intraductal papillary mucinous neoplasm, mucinous cystic neoplasm, and pancreatic intraepithelial neoplasia for the general surgical pathologist.

DATA SOURCES

- The current literature was analyzed and the authors' experiences with institutional and consult material were incorporated.

CONCLUSIONS

- Our understanding of the molecular alterations that lead from pancreatic precursor lesion to invasive carcinoma continues to evolve. These advances aid clinicians in their treatment decisions and researchers in their search for actionable, druggable targets.

Pancreatic intraductal tubulopapillary neoplasm is genetically distinct from intraductal papillary mucinous neoplasm and ductal adenocarcinoma

Intraductal tubulopapillary neoplasm is a relatively recently described member of the pancreatic intraductal neoplasm family. The more common member of this family, intraductal papillary mucinous neoplasm, often carries genetic alterations typical of pancreatic infiltrating ductal adenocarcinoma (KRAS, TP53, and CDKN2A) but additionally has mutations in GNAS and RNF43 genes. However, the genetic characteristics of intraductal tubulopapillary neoplasm have not been well characterized. Twenty-two intraductal tubulopapillary neoplasms were analyzed by either targeted next-generation sequencing, which enabled the identification of sequence mutations, copy number alterations, and selected structural rearrangements involving all targeted (≥300) genes, or whole-exome sequencing. Three of these intraductal tubulopapillary neoplasms were also subjected to whole-genome sequencing. All intraductal tubulopapillary neoplasms revealed the characteristic histologic (cellular intraductal nodules of back-to-back tubular glands lined by predominantly cuboidal cells with atypical nuclei and no obvious intracellular mucin) and immunohistochemical (immunolabeled with MUC1 and MUC6 but were negative for MUC2 and MUC5AC) features. By genomic analyses, there was loss of CDKN2A in 5/20 (25%) of these cases. However, the majority of the previously reported intraductal papillary mucinous neoplasm-related alterations were absent. Moreover, in contrast to most ductal neoplasms of the pancreas, MAP-kinase pathway was not involved. In fact, 2/22 (9%) of intraductal tubulopapillary neoplasms did not reveal any mutations in the tested genes. However, certain chromatin remodeling genes (MLL1, MLL2, MLL3, BAP1, PBRM1, EED, and ATRX) were found to be mutated in 7/22 (32%) of intraductal tubulopapillary neoplasms and 27% harbored phosphatidylinositol 3-kinase (PI3K) pathway (PIK3CA, PIK3CB, INPP4A, and PTEN) mutations. In addition, 4/18 (18%) of intraductal tubulopapillary neoplasms had FGFR2 fusions (FGFR2-CEP55, FGFR2-SASS6, DISP1-FGFR2, FGFR2-TXLNA, and FGFR2-VCL) and 1/18 (5.5%) had STRN-ALK fusion. Intraductal tubulopapillary neoplasm is a distinct clinicopathologic entity in the pancreas. Although its intraductal nature and some clinicopathologic features resemble those of intraductal papillary mucinous neoplasm, our results suggest that intraductal tubulopapillary neoplasm has distinguishing genetic characteristics. Some of these mutated genes are potentially targetable. Future functional studies will be needed to determine the consequences of these gene alterations.

Comparison of the diagnostic accuracy of three current guidelines for the evaluation of asymptomatic pancreatic cystic neoplasms

Asymptomatic pancreatic cysts are a common clinical problem but only a minority of these cases progress to cancer. Our aim was to compare the accuracy to detect malignancy of the 2015 American Gastroenterological Association (AGA), the 2012 International Consensus/Fukuoka (Fukuoka guidelines [FG]), and the 2010 American College of Radiology (ACR) guidelines.We conducted a retrospective study at 3 referral centers for all patients who underwent resection for an asymptomatic pancreatic cyst between January 2008 and December 2013. We compared the accuracy of 3 guidelines in predicting high-grade dysplasia (HGD) or cancer in resected cysts. We performed logistic regression analyses to examine the association between cyst features and risk of HGD or cancer.A total of 269 patients met inclusion criteria. A total of 228 (84.8%) had a benign diagnosis or low-grade dysplasia on surgical pathology, and 41 patients (15.2%) had either HGD (n = 14) or invasive cancer (n = 27). Of the 41 patients with HGD or cancer on resection, only 3 patients would have met the AGA guideline's indications for resection based on the preoperative cyst characteristics, whereas 30/41 patients would have met the FG criteria for resection and 22/41 patients met the ACR criteria. The sensitivity, specificity, positive predictive value, negative predictive value of HGD, and/or cancer of the AGA guidelines were 7.3%, 88.2%, 10%, and 84.1%, compared to 73.2%, 45.6%, 19.5%, and 90.4% for the FG and 53.7%, 61%, 19.8%, and 88% for the ACR guidelines. In multivariable analysis, cyst size >3 cm, compared to ≤3 cm, (odds ratio [OR] = 2.08, 95% confidence interval [CI] = 1.11, 4.2) and each year increase in age (OR = 1.07, 95% CI = 1.03, 1.11) were positively associated with risk of HGD or cancer on resection.In patients with asymptomatic branch duct-intraductal papillary mucinous neoplasms or mucinous cystic neoplasms who underwent resection, the prevalence rate of HGD or cancer was 15.2%. Using the 2015 AGA criteria for resection would have missed 92.6% of patients with HGD or cancer. The more "inclusive" FG and ACR had a higher sensitivity for HGD or cancer but lower specificity. Given the current deficiencies of these guidelines, it will be important to determine the acceptable rate of false-positives in order to prevent a single true-positive.

Insights into the Pathogenesis of Pancreatic Cystic Neoplasms

With the current epidemic of diagnosed pancreatic cystic neoplasms on the rise, a substantial amount of work has been done to unravel their biology, thus leading to implications on clinical decision making. Recent genetic profiling of resected human specimens has identified alterations in signaling pathways involving KRAS and GNAS signaling as early events in the pathogenesis of intraductal pancreatic mucinous neoplasms. Progressively, mutations in genes such as TP53, SMAD4, RNF43, and others are thought to characterize invasive and advanced lesions. The role of inflammation in fueling the growth and transformation of these cysts has also begun to be studied with greater interest. A number of promising clinical studies have attempted to integrate these genetic insights into classifying these cysts and treating patients. We have reviewed existing literature on similar lines besides commenting on some useful animal models that recapitulate molecular and phenotypic progression of these cysts.

Molecular Genetics of Pancreatic Neoplasms

Pancreatic neoplasms have a wide range of histologic types with distinct clinical outcomes. Recent advances in high-throughput sequencing technologies have greatly deepened our understanding of pancreatic neoplasms. Now, the exomes of major histologic types of pancreatic neoplasms have been sequenced, and their genetic landscapes have been revealed. This article reviews the molecular changes underlying pancreatic neoplasms, with a special focus on the genetic changes that characterize the histologic types of pancreatic neoplasms. Emphasis is also made on the molecular features of key genes that have the potential for therapeutic targets.

Mutant allele specific imbalance in oncogenes with copy number alterations: Occurrence, mechanisms, and potential clinical implications

Mutant allele specific imbalance (MASI) was initially coined to describe copy number alterations associated with the mutant allele of an oncogene. The copy number gain (CNG) specific to the mutant allele can be readily observed in electropherograms. With the development of genome-wide analyses at base-pair resolution with copy number counts, we can now further differentiate MASI into those with CNG, with copy neutral alteration (also termed acquired uniparental disomy; UPD), or with loss of heterozygosity (LOH) due to the loss of the wild-type (WT) allele. Here we summarize the occurrence of MASI with CNG, aUPD, or MASI with LOH in some major oncogenes (such as EGFR, KRAS, PIK3CA, and BRAF). We also discuss how these various classifications of MASI have been demonstrated to impact tumorigenesis, progression, metastasis, prognosis, and potentially therapeutic responses in cancer, notably in lung, colorectal, and pancreatic cancers.

Nature and management of pancreatic mucinous cystic neoplasm (MCN): A systematic review of the literature

BACKGROUND

The current management of pancreatic mucinous cystic neoplasms (MCN) is defined by the consensus European, International Association of Pancreatology and American College of Gastroenterology guidelines. However, the criterion for surgical resection remains uncertain and differs between these guidelines. Therefore through this systematic review of the existing literature we aimed to better define the natural history and prognosis of these lesions, in order to clarify recommendations for future management.

METHODS

A systematic literature search was performed (PubMed, EMBASE, Cochrane Library) for studies published in the English language between 1970 and 2015.

RESULTS

MCNs occur almost exclusively in women (female:male 20:1) and are mainly located in the pancreatic body or tail (93-95%). They are usually found incidentally at the age of 40-60 years. Cross-sectional imaging and endoscopic ultrasound are the most frequently used diagnostic tools, but often it is impossible to differentiate MCNs from branch duct intraductal papillary mucinous neoplasms (BD-IPMN) or oligocystic serous adenomas pre-operatively. In resected MCNs, 0-34% are malignant, but in those less than 4 cm only 0.03% were associated with invasive adenocarcinoma. No surgically resected benign MCNs were associated with a synchronous lesion or recurrence; therefore further follow-up is not required after resection. Five-year survival after surgical resection of a malignant MCN is approximately 60%.

CONCLUSIONS

Compared to other pancreatic tumors, MCNs have a low aggressive behavior, with exceptionally low rates of malignant transformation when less than 4 cm in size, are asymptomatic and lack worrisome features on pre-operative imaging. This differs significantly from the natural history of small BD-IPMNs, supporting the need to differentiate mucinous cyst subtypes pre-operatively, where possible. The findings support the recommendations from the recent European Consensus Guidelines, for the more conservative management of MCNs.

KRAS-related proteins in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is a highly metastatic disease with a high mortality rate. Genetic and biochemical studies have shown that RAS signaling mediated by KRAS plays a pivotal role in disease initiation, progression and drug resistance. RAS signaling affects several cellular processes in PDAC, including cellular proliferation, migration, cellular metabolism and autophagy. 90% of pancreatic cancer patients harbor somatic oncogenic point mutations in KRAS, which lead to constitutive activation of the molecule. Pancreatic cancers lacking KRAS mutations show activation of RAS via upstream signaling through receptor mediated tyrosine kinases, like EGFR, and in a small fraction of patients, oncogenic activation of the downstream B-RAF molecule is detected. RAS-stimulated signaling of RAF/MEK/ERK, PI3K/AKT/mTOR and RalA/B is active in human pancreatic cancers, cancer cell lines and mouse models of PDAC, although activation levels of each signaling arm appear to be variable across different tumors and perhaps within different subclones of single tumors. Recently, several targeted therapies directed towards MEK, ERK, PI3K and mTOR have been assayed in pancreatic cancer cell lines and in mouse models of the disease with promising results for their ability to impede cellular growth or delay tumor formation, and several inhibitors are currently in clinical trials. However, therapy-induced cross activation of RAS effector molecules has elucidated the complexities of targeting RAS signaling. Combinatorial therapies are now being explored as an approach to overcome RAS-induced therapeutic resistance in pancreatic cancer.

The oncocytic subtype is genetically distinct from other pancreatic intraductal papillary mucinous neoplasm subtypes

In 2010, the World Health Organization reclassified the entity originally described as intraductal oncocytic papillary neoplasm as the 'oncocytic subtype' of intraductal papillary mucinous neoplasm. Although several key molecular alterations of other intraductal papillary mucinous neoplasm subtypes have been discovered, including common mutations in KRAS, GNAS, and RNF3, those of oncocytic subtype have not been well characterized. We analyzed 11 pancreatic 'oncocytic subtype' of intraductal papillary mucinous neoplasms. Nine pancreatic 'oncocytic subtype' of intraductal papillary mucinous neoplasms uniformly exhibited typical entity-defining morphology of arborizing papillae lined by layers of cells with oncocytic cytoplasm, prominent, nucleoli, and intraepithelial lumina. The remaining two were atypical. One lacked the arborizing papilla and had flat oncocytic epithelium only; the other one had focal oncocytic epithelium in a background of predominantly intestinal subtype intraductal papillary mucinous neoplasm. Different components of this case were analyzed separately. Formalin-fixed, paraffin-embedded specimens of all cases were microdissected and subjected to high-depth-targeted next-generation sequencing for a panel of 300 key cancer-associated genes in a platform that enabled the identification of sequence mutations, copy number alterations, and select structural rearrangements involving all targeted genes. Fresh frozen specimens of two cases were also subjected to whole-genome sequencing. For the nine typical pancreatic 'oncocytic subtype' of intraductal papillary mucinous neoplasms, the number of mutations per case, identified by next-generation sequencing, ranged from 1 to 10 (median=4). None of these cases had KRAS or GNAS mutations and only one had both RNF43 and PIK3R1 mutations. ARHGAP26, ASXL1, EPHA8, and ERBB4 genes were somatically altered in more than one of these typical 'oncocytic subtype' of intraductal papillary mucinous neoplasms but not in the other two atypical ones. In the neoplasm with flat oncocytic epithelium, the only mutated gene was KRAS. All components of the intestinal subtype intraductal papillary mucinous neoplasms with focal oncocytic epithelium manifested TP53, GNAS, and RNF43 mutations. In conclusion, this study elucidates that 'oncocytic subtype' of intraductal papillary mucinous neoplasm is not only morphologically distinct but also genetically distinct from other intraductal papillary mucinous neoplasm subtypes. Considering that now its biologic behavior is also being found to be different than other intraductal papillary mucinous neoplasm subtypes, 'oncocytic subtype' of intraductal papillary mucinous neoplasm warrants being recognized separately.

Genetics and biology of pancreatic ductal adenocarcinoma

Ying et al. review pancreatic ductal adenocarcinoma (PDAC) genetics and biology, particularly altered cancer cell metabolism, the complexity of immune regulation in the tumor microenvironment, and impaired DNA repair processes.

With 5-year survival rates remaining constant at 6% and rising incidences associated with an epidemic in obesity and metabolic syndrome, pancreatic ductal adenocarcinoma (PDAC) is on track to become the second most common cause of cancer-related deaths by 2030. The high mortality rate of PDAC stems primarily from the lack of early diagnosis and ineffective treatment for advanced tumors. During the past decade, the comprehensive atlas of genomic alterations, the prominence of specific pathways, the preclinical validation of such emerging targets, sophisticated preclinical model systems, and the molecular classification of PDAC into specific disease subtypes have all converged to illuminate drug discovery programs with clearer clinical path hypotheses. A deeper understanding of cancer cell biology, particularly altered cancer cell metabolism and impaired DNA repair processes, is providing novel therapeutic strategies that show strong preclinical activity. Elucidation of tumor biology principles, most notably a deeper understanding of the complexity of immune regulation in the tumor microenvironment, has provided an exciting framework to reawaken the immune system to attack PDAC cancer cells. While the long road of translation lies ahead, the path to meaningful clinical progress has never been clearer to improve PDAC patient survival.

American Gastroenterological Association guidelines are inaccurate in detecting pancreatic cysts with advanced neoplasia: a clinicopathologic study of 225 patients with supporting molecular data

BACKGROUND AND AIMS

The American Gastroenterological Association (AGA) recently reported evidence-based guidelines for the management of asymptomatic neoplastic pancreatic cysts. These guidelines advocate a higher threshold for surgical resection than prior guidelines and imaging surveillance for a considerable number of patients with pancreatic cysts. The aims of this study were to assess the accuracy of the AGA guidelines in detecting advanced neoplasia and present an alternative approach to pancreatic cysts.

METHODS

The study population consisted of 225 patients who underwent EUS-guided FNA for pancreatic cysts between January 2014 and May 2015. For each patient, clinical findings, EUS features, cytopathology results, carcinoembryonic antigen analysis, and molecular testing of pancreatic cyst fluid were reviewed. Molecular testing included the assessment of hotspot mutations and deletions for KRAS, GNAS, VHL, TP53, PIK3CA, and PTEN.

RESULTS

Diagnostic pathology results were available for 41 patients (18%), with 13 (6%) harboring advanced neoplasia. Among these cases, the AGA guidelines identified advanced neoplasia with 62% sensitivity, 79% specificity, 57% positive predictive value, and 82% negative predictive value. Moreover, the AGA guidelines missed 45% of intraductal papillary mucinous neoplasms with adenocarcinoma or high-grade dysplasia. For cases without confirmatory pathology, 27 of 184 patients (15%) with serous cystadenomas (SCAs) based on EUS findings and/or VHL alterations would continue magnetic resonance imaging (MRI) surveillance. In comparison, a novel algorithmic pathway using molecular testing of pancreatic cyst fluid detected advanced neoplasias with 100% sensitivity, 90% specificity, 79% positive predictive value, and 100% negative predictive value.

CONCLUSIONS

The AGA guidelines were inaccurate in detecting pancreatic cysts with advanced neoplasia. Furthermore, because the AGA guidelines manage all neoplastic cysts similarly, patients with SCAs will continue to undergo unnecessary MRI surveillance. The results of an alternative approach with integrative molecular testing are encouraging but require further validation.