Mutational analyses of multiple oncogenic pathways in intraductal papillary mucinous neoplasms 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.

BRAF V600E and Novel Somatic Mutations in Thyroid Cancer of Libyan Patients

BACKGROUND

Thyroid cancer (TC) is a common endocrine malignancy that frequently harbours the oncogenic V600E BRAF mutation. This mutation has received considerable attention in recent years for its potential utility in the risk stratification and management of TC. This study aims to investigate BRAF mutational status in thyroid cancer of Libyan patients and their association with clinicopathological factors.

METHODS

44 thyroid tissue samples were analysed for mutations in exon 15 of the BRAF gene by performing polymerase chain reaction and Sanger sequencing. The results of BRAF mutation screening were correlated to clinical and pathological characteristics of the studied thyroid cancer patients. Statistical analyses were performed using SPSS.

RESULTS

The BRAF exon 15 mutations were detected in 19 (43.2%) of the thyroid cancer cases. The V600E was the most frequent one found in 15/44 (34.1%) cases. We also detected 6 other variants in 7 patients (15.9%), the S616F, the W619R and the T599S. Three mutations were associated with V600E, the L584I, the D587Y and the synonymous L597L. None of these mutations were reported previously in thyroid cancers. No statistical association was found between BRAF mutations and clinicopathological factors except with papillary thyroid cancer type (p= 0,032).

CONCLUSIONS

Novel BRAF mutations and V600E were frequently detected in thyroid cancer of Libyan patients; this suggests a potential role of these novel mutations in carcinogenesis and in anti-EGFR therapy resistance.

Cystic pancreatic lesions, the endless dilemma

Cystic pancreatic lesions involve a wide variety of pathological entities that include neoplastic and non-neoplastic lesions. The proper diagnosis, differentiation, and staging of these cystic lesions are considered a crucial issue in planning further management. There are great challenges for their diagnostic models. In our time, new emerging methods for this diagnosis have been discovered. Endoscopic ultrasonography-guided fine-needle aspiration cytology with chemical and molecular analysis of cyst fluid and EUS-guided fine needle-based confocal laser endomicroscopy, through the needle microforceps biopsy, and single-operator cholangioscopy/pancreatoscopy are promising methods that have been used in the diagnosis of cystic pancreatic lesions. Hereby we discuss the diagnosis of cystic pancreatic lesions and the benefits of various diagnostic models.

Signal transduction pathway mutations in gastrointestinal (GI) cancers: a systematic review and meta-analysis

The present study was conducted to evaluate the prevalence of the signaling pathways mutation rate in the Gastrointestinal (GI) tract cancers in a systematic review and meta-analysis study. The study was performed based on the PRISMA criteria. Random models by confidence interval (CI: 95%) were used to calculate the pooled estimate of prevalence via Metaprop command. The pooled prevalence indices of signal transduction pathway mutations in gastric cancer, liver cancer, colorectal cancer, and pancreatic cancer were 5% (95% CI: 3-8%), 12% (95% CI: 8-18%), 17% (95% CI: 14-20%), and 20% (95% CI: 5-41%), respectively. Also, the mutation rates for Wnt pathway and MAPK pathway were calculated to be 23% (95% CI, 14-33%) and 20% (95% CI, 17-24%), respectively. Moreover, the most popular genes were APC (in Wnt pathway), KRAS (in MAPK pathway) and PIK3CA (in PI3K pathway) in the colorectal cancer, pancreatic cancer, and gastric cancer while they were beta-catenin and CTNNB1 in liver cancer. The most altered pathway was Wnt pathway followed by the MAPK pathway. In addition, pancreatic cancer was found to be higher under the pressure of mutation compared with others based on pooled prevalence analysis. Finally, APC mutations in colorectal cancer, KRAS in gastric cancer, and pancreatic cancer were mostly associated gene alterations.

Intraductal Pancreatic Mucinous Neoplasms: A Tumor-Biology Based Approach for Risk Stratification

Pancreatic ductal adenocarcinoma is one of the most lethal human cancers. Its precursor lesions include pancreatic intra-epithelial neoplasia, mucinous cystic neoplasm, and intraductal papillary mucinous neoplasm (IPMN). IPMNs usually present as an incidental finding at imaging in 2.6% of the population and, according to the degree of dysplasia, they are classified as low- or high-grade lesions. Since the risk of malignant transformation is not accurately predictable, the management of these lesions is based on morphological and clinical parameters, such as presence of mural nodule, main pancreatic duct dilation, presence of symptoms, or high-grade dysplasia. Although the main genetic alterations associated to IPMNs have been elucidated, they are still not helpful for disease risk stratification. The growing body of genomic and epigenomic studies along with the more recent development of organotypic cultures provide the opportunity to improve our understanding of the malignant transformation process, which will likely deliver biomarkers to help discriminate between low- and high-risk lesions. Recent insights on the topic are herein summarized.

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.

Cytologic Analysis of Pancreatic Juice Increases Specificity of Detection of Malignant IPMN-A Systematic Review

BACKGROUND & AIMS

Intraductal papillary mucinous neoplasms (IPMNs) of the pancreas can progress to cancer. Biomarkers have been identified that were reported to increase the accuracy of identification of malignant lesions; we performed a systematic review of the accuracy of these markers.

METHODS

We performed a systematic review of published studies on biomarkers of malignant IPMNs by searching MEDLINE and Web of Science databases from January 2005 through December 2017. Our methods were developed based on the Meta-analysis Of Observational Studies in Epidemiology guidelines. Pooled sensitivity, specificity, receiver operating characteristic curves, and their respective areas under the curve (AUC) were calculated from groups of markers (cell-, protein-, or DNA-based) measured in samples collected before and after surgery. A hypothetical test model was developed to determine how to meaningfully amend the revised Fukuoka guidelines, focusing on increasing test specificity for patients with IPMNs that have worrisome features.

RESULTS

We collected data from 193 published studies, comprising 12,297 patients, that analyzed 7 preoperative and 21 postoperative markers of IPMNs. The 3 biomarkers that identified malignant IPMNs with the largest AUC values were pancreatic juice cytology (AUC, 0.84; sensitivity, 0.54; specificity, 0.91), serum protein carbohydrate antigen 19-9 (AUC, 0.81; sensitivity, 0.45; specificity, 0.90), and cyst fluid cytology (AUC, 0.82; sensitivity, 0.57; specificity, 0.84). A combination of cytologic and immunohistochemical analysis of MUC1 and MUC2 in pancreatic juice samples identified malignant IPMNs with the largest AUC and sensitivity values (AUC, 0.85; sensitivity, 0.85; specificity, 0.65). In a test model, inclusion of cytologic analysis of pancreatic juice in the guideline algorithm significantly increased the specificity of detection of malignant IPMNs.

CONCLUSIONS

In a systematic review, we found cytologic analysis of pancreatic juice to have the greatest effect in increasing the specificity of detection of malignant IPMNs. We propose addition of this test to the Fukuoka guidelines for assessment of patients with IPMNs with worrisome features.

Metastatic Pancreatic Cancer Response to Treatment with Cetuximab and Gemcitabine plus Capecitabine: A Case Report and Review of the Literature

The treatment of pancreatic cancer remains a formidable challenge to clinicians. Here we describe the case of a 57-year-old man with metastatic pancreatic cancer who received combination treatment with cetuximab and capecitabine plus gemcitabine for four cycles. Repeat CT scan showed that the size of both the primary tumor in the pancreas and the metastatic lesions in the liver had shrunk significantly. Rapid reduction of the serum CA19-9 level was observed, and no serious toxic events occurred. The patient had a progression-free survival of eight months at the time we wrote this paper. The combination of cetuximab and capecitabine plus gemcitabine may be a useful therapy in metastatic pancreatic cancer. Free full text available at www.tumorionline.it

Modeling the Iatrogenic Pancreatic Cancer Risk After Islet Autotransplantation in Mouse

Iatrogenic pancreatic cancer metastasis after islet infusion is a potential risk of islet autotransplantation performed after pancreatectomy. To model this risk, islets and/or pancreatic exocrine clusters obtained from a genetically engineered mouse model for pancreatic ductal adenocarcinoma (the LSL-Kras^G12D/+ ;LSL-Trp53^R172H/+ ;Pdx-1-Cre, termed KPC mouse) were transplanted via the portal vein in syngeneic wild type (WT) severely diabetic recipients in the following treatment groups: group A (n = 11) received KPC exocrine clusters in volume equal to 250 islet equivalents (IEQs); group B (n = 12) received 250 WT IEQs mixed with KPC exocrine clusters (1:1 volume ratio); group C (n = 5) received 250 KPC IEQs, and group D (n = 7) received 250 WT IEQs. The incidence of hepatic metastasis was assessed by magnetic resonance imaging and histology over the 13 months of follow-up. Overall survival was not different in the four groups. No mice developed liver metastases during the follow-up. Two mice developed spontaneous tumors: a liver hepatocellular tumor in group A and a malignant lymphoma in group D. Islets and/or exocrine clusters obtained by KPC mouse, a model that develops pancreatic cancer with 100% penetrance, do not retain the same risk of tumor development when transplanted via the portal vein in a syngeneic diabetic recipient.

KRAS, GNAS, and RNF43 mutations in intraductal papillary mucinous neoplasm of the pancreas: a meta-analysis

Background

The prevalence and clinical significances of KRAS, GNAS, and RNF43 mutations in patients with pancreatic intraductal papillary mucinous neoplasm (IPMN) remain elusive. To evaluate the incidence of the gene mutations and clinicopathologic differences between KRAS and GNAS mutations in pancreatic cystic lesions, we performed a meta-analysis of published 33 KRAS, 11 GNAS, and 4 RNF43 studies including 1253, 835, and 143 cases, respectively.

Methods

We pooled the results of relevant studies identified using the PubMed and EMBASE databases. The effect sizes of outcome parameters were computed by the prevalence rate, weighted mean difference, or odds ratio (OR) using a random-effects model.

Results

The pooled prevalence of KRAS, GNAS, and RNF43 mutations in IPMN was 61, 56, and 23 %, respectively. The KRAS (OR 7.4 and 71.2) and GNAS (OR 30.2 and 15.3) mutations were more frequently found in IPMNs than in mucinous cystic neoplasms and in serous cystadenomas, respectively. Of the microscopic subtypes of IPMN, KRAS and GNAS were frequently mutated in gastric type (OR 2.7, P < 0.001) and intestinal type (OR 3.0, P < 0.001), respectively. KRAS mutation was infrequently found in high-grade dysplasia lesions of IPMN (OR 0.6, P = 0.032). GNAS mutation was associated with male (OR 1.9, P = 0.012).

Conclusions

This meta-analysis supports that KRAS and GNAS mutations could be diagnostic markers for IPMN. In addition, the frequencies of KRAS and GNAS mutations in IPMNs are highly variable according to the microscopic duct subtypes, reflecting their independent roles in the IPMN-adenocarcinoma sequence.

Electronic supplementary material

The online version of this article (doi:10.1186/s40064-016-2847-4) contains supplementary material, which is available to authorized users.

The genetic classification of pancreatic neoplasia

Cancer is caused by the accumulation of inherited and/or acquired alterations in specific genes. The recent decline in the cost of DNA sequencing has allowed tumor sequencing to be conducted on a large scale, which, in turn, has led to an unprecedented understanding of the genetic events that drive neoplasia. This understanding, when integrated with meticulous histologic analyses and with clinical findings, has direct clinical implications. The recent sequencing of all of the major types of cystic and noncystic neoplasms of the pancreas has revealed opportunities for molecular diagnoses and for personalized treatment. This review summarizes the results from these recent studies focusing on the clinical relevance of genomic data.

Intraductal papillary mucinous neoplasm: clinical surveillance and management decisions

Intraductal papillary mucinous neoplasm (IPMN) of the pancreas is a relatively rare cystic neoplasm. Although most IPMNs appear to be benign and may be managed by surveillance, all IPMNs are considered premalignant lesions with malignant potential. As such, current efforts are focused on identifying those neoplasms that are at high risk for malignancy to optimize treatment strategy and outcome. IPMNs with invasive carcinoma have clinical outcomes that approach those of conventional pancreatic ductal adenocarcinoma. Management guidelines recommend surgical resection for IPMNs with high-risk imaging or cytologic features. The role of adjuvant therapy is unclear, and we review the evidence for chemoradiation here. Some studies suggest adjuvant chemoradiation may have the greatest impact in malignant IPMNs with adverse histologic features, that is, lymph node metastasis at the time of diagnosis or positive surgical margins. As more IPMNs are recognized and treated, more evidence will accumulate to guide clinicians regarding appropriate use of radiotherapy in the management of IPMN.

Pancreatic cancer genomes: toward molecular subtyping and novel approaches to diagnosis and therapy

Pancreatic neoplasms represent a broad range of clinical entities, many of which have drastic effects on the lives of patients. Recently, high-throughput sequencing analyses have been performed in many pancreatic neoplasms, providing deep insights into the underlying biology of these neoplasms as well as novel approaches to diagnosis and treatment. This review discusses the molecular alterations underlying pancreatic neoplasms as well as the clinical impact of these alterations for diagnosis and treatment.

Integration of KRAS testing in the diagnosis of pancreatic cystic lesions: a clinical experience of 618 pancreatic cysts

With improvements in abdominal imaging, detection of incidental pancreatic cysts are becoming increasingly common. Analysis of pancreatic cyst fluid from fine-needle aspiration is particularly important in identifying intraductal papillary mucinous neoplasms (IPMNs) and mucinous cystic neoplasms (MCNs), which have significant implications in clinical intervention and follow-up. Previous controlled studies have shown that KRAS mutations in cyst fluid are highly specific for mucinous differentiation in pancreatic cysts; however, this has not been examined in the clinical setting. Over a 6-year study period, 618 pancreatic cyst fluids obtained by fine-needle aspiration at the time of endoscopic ultrasound were tested for KRAS mutations as part of routine evaluation for a cystic neoplasm. Of the 618 specimens, 603 (98%) from 546 patients were satisfactory for molecular analysis. Patients ranged in age from 17 to 90 years (mean, 63.9 years) and were predominantly female (68%). Pancreatic cysts were relatively evenly distributed throughout the pancreas and ranged in size from 0.6 to 11.0 cm (mean, 2.3 cm). Mutations in KRAS were detected in 232 of 603 (38%) aspirates. Although sufficient for molecular analysis, 320 of 603 (53%) specimens were either less than optimal (38%) or unsatisfactory (15%) for cytopathologic diagnosis. Surgical follow-up information was available for 142 (26%) patients and consisted of 53 KRAS-mutated and 89 KRAS-wild-type cysts. Overall, KRAS mutations had a specificity of 100%, but a sensitivity of 54% for mucinous differentiation. When stratified by cyst type, KRAS had a sensitivity of 67% and 14% for IPMNs and MCNs, respectively. In summary, KRAS mutations were highly specific for mucinous differentiation, but were inadequate in identifying MCNs. Future molecular studies and the combination of other fluid markers are required to improve the detection and classification of pancreatic mucinous neoplasms by endoscopic ultrasound fine-needle aspiration.

Pathology and molecular genetics of pancreatic neoplasms

Cancer is fundamentally a genetic disease caused by the accumulation of somatic mutations in oncogenes and tumor suppressor genes. In the last decade, rapid advances in sequencing and bioinformatic technology led to an explosion in sequencing studies of cancer genomes, greatly expanding our knowledge of the genetic changes underlying a variety of tumor types. Several of these studies of cancer genomes have focused on pancreatic neoplasms, and cancers from the pancreas are some of the best characterized tumors at the genetic level. Pancreatic neoplasms encompass a wide array of clinical diseases, from benign cysts to deadly cancers, and the genetic alterations underlying neoplasms of the pancreas are similarly diverse. This new knowledge of pancreatic cancer genomes has deepened our understanding of tumorigenesis in the pancreas and has opened several promising new avenues for novel diagnostics and therapeutics.

Risk factors for intraductal papillary mucinous neoplasm (IPMN) of the pancreas: a multicentre case-control study

OBJECTIVES

To investigate environmental, personal, and hereditary risk factors associated with the occurrence of intraductal papillary mucinous neoplasms of the pancreas (IPMNs).

METHODS

Multicentre case-control study. Risk factors were identified from a questionnaire collecting data on family and medical history, and environmental factors. Cases were prevalent IPMNs seen at the participating units within an 18-month timeframe. Matched controls were enrolled alongside patients seen at outpatient clinics.

RESULTS

Three-hundred and ninety patients with IPMN and 390 matched controls (166 males, mean age 65 in each group) were enrolled. Of the IPMNs, 310 had branch-duct involvement and 80 main-duct involvement. The only cancer with a 1st degree family history significantly higher in IPMN was pancreatic ductal adenocarcinoma (PDAC) (5.4% vs. 1.5%). Previous history of diabetes (13.6% vs. 7.5%), chronic pancreatitis (CP) (3.1% vs. 0.3%), peptic ulcer (7.2% vs. 4.3%), and insulin use (4.9% vs. 1.1%) were all more frequent with IPMNs. Logistic regression multivariate analysis revealed that history of diabetes (odds ratio (OR): 1.79, confidence interval (CI) 95%: 1.08-2.98), CP (OR: 10.10, CI 95%: 1.30-78.32), and family histories of PDAC (OR: 2.94, CI 95%: 1.17-7.39) were all independent risk factors. However, when analysis was restricted to diabetics who had taken insulin, risk of IPMN became stronger (OR: 6.03, CI 95%: 1.74-20.84). The association with all these risk factors seemed stronger for the subgroup with main duct involvement.

CONCLUSIONS

A previous history of diabetes, especially with insulin use, CP, and family history of PDAC are all relevant risk factors for the development of IPMN. These results suggest an overlap between certain risk factors for PDAC and IPMN.

Intraductal papillary mucinous neoplasm of the pancreas: an update

Intraductal papillary mucinous neoplasm (IPMN) is a cystic tumor of the pancreas. The etiology is unknown, but increasing evidence suggests the involvement of several tumorigenesis pathways, including an association with hereditary syndromes. IPMN occurs more commonly in men, with the mean age at diagnosis between 64 and 67 years old. At the time of diagnosis, it may be benign, with or without dysplasia, or frankly malignant with an invasive carcinoma. Tumors arising from the main pancreatic duct are termed main-duct IPMNs, those involving the branch ducts, branch-duct IPMNs. In general, small branch-duct IPMNs are benign, particularly in asymptomatic patients, and can be safely followed. In contrast, main-duct tumors should be surgically resected and examined carefully for an invasive component. In the absence of invasion, patient's survival is excellent, from 94 to 100%. For patients with an IPMN-associated invasive carcinoma, the prognosis overall is better than those with a de novo pancreatic ductal adenocarcinoma, with a 5-year survival of 40% to 60% in some series. However, no survival advantage can be demonstrated if the invasive component in an IPMN patient is that of the conventional tubular type (versus mucinous carcinoma). Several histomorphologic variants are recognized, although the clinical significance of this "subtyping" is not well defined.

Genetic markers of malignant transformation in intraductal papillary mucinous neoplasm of the pancreas: a meta-analysis

OBJECTIVES

The objective of this study was to determine the relationship between specific genetic alterations and malignant transformation in intraductal papillary mucinous neoplasm (IPMN) of the pancreas.

METHODS

Quantitative meta-analysis was conducted of studies through October 2010 that adhered to the 1996 World Health Organization guidelines for distinguishing adenoma and borderline IPMN versus carcinoma in surgically resected specimens using a random-effects model. We developed a 6-point scoring system to assess study quality.

RESULTS

Thirty-nine studies (1235 IPMN samples) satisfied the inclusion criteria, and we conducted pooled analysis of 8 genetic markers: MUC1, MUC2, MUC5AC, kRas, p53, hTERT (human telomerase reverse transcriptase), cyclooxygenase 2, and Shh (Sonic hedgehog). Markers having the strongest association with malignant IPMN were hTERT (odds ratio [OR], 11.4; 95% confidence interval [CI], 3.5-36.7) and Shh (OR, 6.9; 95% CI, 2.4-20.2), whereas MUC5AC (OR, 1.0; 95% CI, 0.1-13.9) and kRas (OR, 2.0; 95% CI, 1.0-4.3) showed weak association with IPMN histologic progression.

CONCLUSIONS

Expression of hTERT is strongly associated with malignant transformation in IPMN, consistent with up-regulation of hTERT as a key step in progression of IPMN to cancer. Expression of kRas and MUC5AC is common but not strongly associated with IPMN histologic progression. The quality criteria used here may guide future reporting of genetic markers related to malignant transformation of IPMN.

Mutation and genomic amplification of the PIK3CA proto-oncogene in pituitary adenomas

The tumorigenesis of pituitary adenomas is poorly understood. Mutations of the PIK3CA proto-oncogene, which encodes the p110-α catalytic subunit of PI3K, have been reported in various types of human cancers regarding the role of the gene in cell proliferation and survival through activation of the PI3K/Akt signaling pathway. Only one Chinese study described somatic mutations and amplification of the PIK3CA gene in a large series of pituitary adenomas. The aim of the present study was to determine genetic alterations of PIK3CA in a second series that consisted of 33 pituitary adenomas of different subtypes diagnosed by immunohistochemistry: 6 adrenocorticotropic hormone-secreting microadenomas, 5 growth hormone-secreting macroadenomas, 7 prolactin-secreting macroadenomas, and 15 nonfunctioning macroadenomas. Direct sequencing of exons 9 and 20 assessed by qPCR was employed to investigate the presence of mutations and genomic amplification defined as a copy number ≥4. Previously identified PIK3CA mutations (exon 20) were detected in four cases (12.1%). Interestingly, the Chinese study reported mutations only in invasive tumors, while we found a PIK3CA mutation in one noninvasive corticotroph microadenoma. PIK3CA amplification was observed in 21.2% (7/33) of the cases. This study demonstrates the presence of somatic mutations and amplifications of the PIK3CA gene in a second series of pituitary adenomas, corroborating the previously described involvement of the PI3K/Akt signaling pathway in the tumorigenic process of this gland.

Somatic mutations in PIK3CA and activation of AKT in intraductal tubulopapillary neoplasms of the pancreas

Intraductal tubulopapillary neoplasm (ITPN) is a recently recognized rare variant of intraductal neoplasms of the pancreas. Molecular aberrations underlying the neoplasm remain unknown. We investigated somatic mutations in PIK3CA, PTEN, AKT1, KRAS, and BRAF. We also investigated aberrant expressions of phosphorylated AKT, phosphatase and tensin homolog (PTEN), tumor protein 53 (TP53), SMAD4, and CTNNB1 in 11 cases of ITPNs and compared these data with those of 50 cases of intraductal papillary mucinous neoplasm (IPMN), another distinct variant of pancreatic intraductal neoplasms. Mutations in PIK3CA were found in 3 of 11 ITPNs but not in IPMNs (P = 0.005; Fisher exact test). In contrast, mutations in KRAS were found in none of the ITPNs but were found in 26 of the 50 IPMNs (P = 0.001; Fisher exact test). PIK3CA mutations were associated with strong expression of phosphorylated AKT (P < 0.001; the Mann-Whitney U test). Moreover, the expression of phosphorylated AKT was apparent in most ITPNs but only in a few IPMNs (P < 0.001; the Mann-Whitney U test). Aberrant expressions of TP53, SMAD4, and CTNNB1 were not statistically different between these neoplasms. Mutations in PIK3CA and the expression of phosphorylated AKT were not associated with age, sex, tissue invasion, and patients' prognosis in ITPNs. These results indicate that activation of the phosphatidylinositol 3-kinase pathway may play a crucial role in ITPNs but not in IPMNs. In contrast, the mutation in KRAS seems to play a major role in IPMNs but not in ITPNs. The activated phosphatidylinositol 3-kinase pathway may be a potential target for molecular diagnosis and therapy of ITPNs.

Genetic and epigenetic alterations in pancreatic carcinogenesis

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers worldwide. Despite significant progresses in the last decades, the origin of this cancer remains unclear and no efficient therapy exists. PDAC does not arise de novo: three remarkable different types of pancreatic lesions can evolve towards pancreatic cancer. These precursor lesions include: Pancreatic intraepithelial neoplasia (PanIN) that are microscopic lesions of the pancreas, Intraductal Papillary Mucinous Neoplasms (IPMN) and Mucinous Cystic Neoplasms (MCN) that are both macroscopic lesions. However, the cellular origin of these lesions is still a matter of debate.

Classically, neoplasm initiation or progression is driven by several genetic and epigenetic alterations. The aim of this review is to assemble the current information on genetic mutations and epigenetic disorders that affect genes during pancreatic carcinogenesis. We will further discuss the interest of the genetic and epigenetic alterations for the diagnosis and prognosis of PDAC. Large genetic alterations (chromosomal deletion/amplification) and single point mutations are well described for carcinogenesis inducers. Mutations classically occur within key regions of the genome. Consequences are various and include activation of mitogenic pathways or silencing of apoptotic processes. Alterations of K-RAS, P16 and DPC4 genes are frequently observed in PDAC samples and have been described to arise gradually during carcinogenesis. DNA methylation is an epigenetic process involved in imprinting and X chromosome inactivation. Alteration of DNA methylation patterns leads to deregulation of gene expression, in the absence of mutation. Both genetic and epigenetic events influence genes and non-coding RNA expression, with dramatic effects on proliferation, survival and invasion. Besides improvement in our fundamental understanding of PDAC development, highlighting the molecular alterations that occur in pancreatic carcinogenesis could provide new clinical tools for early diagnosis of PDAC and the molecular basis for the development of new effective therapies.

Intraductal papillary mucinous neoplasm

Intraductal papillary mucinous neoplasm (IPMN) is a grossly visible (≥1 cm), mucin-producing neoplasm that arises in the main pancreatic duct and/or its branches. Patients with intraductal papillary mucinous neoplasm can present with symptoms caused by obstruction of the pancreatic duct system, or they can be asymptomatic. There are 3 clinical subtypes of intraductal papillary mucinous neoplasm: main duct, branch duct, and mixed. Five histologic types of intraductal papillary mucinous neoplasm are recognized: gastric foveolar type, intestinal type, pancreatobiliary type, intraductal oncocytic papillary neoplasm, and intraductal tubulopapillary neoplasm. Noninvasive intraductal papillary mucinous neoplasms are classified into 3 grades based on the degree of cytoarchitectural atypia: low-, intermediate-, and high-grade dysplasia. The most important prognosticator, however, is the presence or absence of an associated invasive carcinoma. Some main duct-intraductal papillary mucinous neoplasms progress into invasive carcinoma, mainly tubular adenocarcinoma (conventional pancreatic ductal adenocarcinoma) and colloid carcinoma. Branch duct-intraductal papillary mucinous neoplasms have a low risk for malignant transformation. Preoperative prediction of the malignant potential of an intraductal papillary mucinous neoplasm is of growing importance because pancreatic surgery has its complications, and many small intraductal papillary mucinous neoplasms, especially branch duct-intraductal papillary mucinous neoplasms, have an extremely low risk of progressing to an invasive cancer. Although most clinical decision making relies on imaging, a better understanding of the molecular genetics of intraductal papillary mucinous neoplasm could help identify molecular markers of high-risk lesions. When surgery is performed, intraoperative frozen section assessment of the pancreatic resection margin can guide the extent of resection. Intraductal papillary mucinous neoplasms are often multifocal, and surgically resected patients should be followed for metachronous disease.

Recurrent GNAS mutations define an unexpected pathway for pancreatic cyst development

More than 2% of the adult U.S. population harbors a pancreatic cyst. These often pose a difficult management problem because conventional criteria cannot always distinguish cysts with malignant potential from those that are innocuous. One of the most common cystic neoplasms of the pancreas, and a bona fide precursor to invasive adenocarcinoma, is called intraductal papillary mucinous neoplasm (IPMN). To help reveal the pathogenesis of these lesions, we purified the DNA from IPMN cyst fluids from 19 patients and searched for mutations in 169 genes commonly altered in human cancers. In addition to the expected KRAS mutations, we identified recurrent mutations at codon 201 of GNAS. A larger number (113) of additional IPMNs were then analyzed to determine the prevalence of KRAS and GNAS mutations. In total, we found that GNAS mutations were present in 66% of IPMNs and that either KRAS or GNAS mutations could be identified in 96%. In eight cases, we could investigate invasive adenocarcinomas that developed in association with IPMNs containing GNAS mutations. In seven of these eight cases, the GNAS mutations present in the IPMNs were also found in the invasive lesion. GNAS mutations were not found in other types of cystic neoplasms of the pancreas or in invasive adenocarcinomas not associated with IPMNs. In addition to defining a new pathway for pancreatic neoplasia, these data suggest that GNAS mutations can inform the diagnosis and management of patients with cystic pancreatic lesions.

Differential protein immunoexpression profiles in appendiceal mucinous neoplasms: a special reference to classification and predictive factors

Appendiceal mucinous neoplasms have been the focus of considerable debate in recent years. We histologically classified 70 appendiceal mucinous neoplasms into three categories: 32 mucinous adenoma, 23 mucinous neoplasm of uncertain malignant potential, and 15 mucinous adenocarcinomas. Immunohistochemistry was performed for 24 proteins in different functional categories, specifically, oncogenic proteins (bcl-2, beta-catenin, CEA, C-erbB2, c-kit, Cox-2, Cyclin D1, EGFR, Ki-67, NF-kappaB, VEGF), tumor suppressors (E-cadherin, FHIT, hMLH1, p53, p63, smad4), cell-cycle regulators (p21, p27, p16), and mucin proteins (MUC1, MUC2, MUC5AC, MUC6). Our data showed that 9 out of the 24 proteins were more frequently altered in the mucinous adenocarcinoma group than in the mucinous adenoma group (P<0.05), including beta-catenin (13% in mucinous adenoma vs 60% in mucinous adenocarcinoma), CyclinD1 (44 vs 87%), Ki-67 (high labeling index: 31 vs 67%), NF-kappaB (19 vs 60%), VEGF (16 vs 87%), E-cadherin (0 vs 47%), p53 (6 vs 40%), MUC2 (9 vs 67%), and MUC5AC (3 vs 40%). The distinct immunoexpression profile of mucinous neoplasm of uncertain malignant potential was placed between those of mucinous adenoma and mucinous adenocarcinoma (P<0.05). Moreover, the mucinous adenoma, mucinous neoplasm of uncertain malignant potential, and mucinous adenocarcinoma categories displayed differences in terms of the number of altered markers among the nine proteins (P<0.05; mean 1.4 vs 2.6 vs 5.5, respectively). In mucinous adenocarcinoma, the p53 status was related to disease-free survival and overall survival of patients (P<0.05, both). NF-kappaB status and the number of altered protein markers made statistically marginal impacts on disease-free survival; also beta-catenin loss, on overall survival of patients. In conclusion, protein immunoexpression profiles may facilitate the classification of appendiceal mucinous neoplasms. In our study, the three tumor categories of mucinous adenoma, mucinous neoplasm of uncertain malignant potential, and mucinous adenocarcinoma exhibited distinct immunoexpression profiles. Five and more altered protein markers, p53 overexpression, NF-kappaB positivity, and beta-catenin loss were predictive factors of adverse clinical outcomes in appendiceal mucinous adenocarcinomas.

Multidisciplinary approach to diagnosis and management of intraductal papillary mucinous neoplasms of the pancreas

Intraductal papillary mucinous neoplasms have gained recognition in recent years as premalignant precursors to pancreatic cancer that enable early detection and often are found incidentally at imaging. Accurate diagnosis and optimal, finely tuned management of these lesions are important and require collaboration across various disciplines, including radiology, endoscopy, surgery, and pathology. Several imaging modalities can visualize these lesions adequately, each with specific advantages and disadvantages. Multidetector computed tomography and magnetic resonance cholangiopancreatography are generally the first-line imaging modalities; endoscopic imaging such as endoscopic ultrasound and endoscopic retrograde cholangiopancreatography are beneficial when the former 2 modalities are equivocal. Surgical candidates generally include patients with main duct lesions or branch duct lesions greater than 3 cm or any possessing a solid component. A management algorithm indicating when surgery should be pursued is proposed. For nonsurgical and postsurgical patients, follow-up management is important to monitor growth and recurrence, and risks from repeated radiation exposure should be taken into account. Furthermore, issues of multifocality and increased predisposition of the pancreas to ductal adenocarcinoma must be addressed at follow-up evaluation. A follow-up management algorithm also is proposed in this review.

Molecular biology of pancreatic cancer

Pancreatic cancer is a leading cause of cancer death. This devastating disease has the horrible honour of close to equal incidence and mortality rates. Late diagnosis and a constitutive resistance to every chemotherapy approach are responsible for this scenario. However, molecular biology tools in cooperation with translational efforts have dissected several secrets that underlie pancreatic cancer. Progressive acquisition of malignant, invasive phenotypes from pre-malignant lesions, recent revelations on core signalling pathways and new targeted designed trials offer a better future for pancreatic cancer patients. This review will summarise recent advances in the molecular biology of pancreatic cancer.