Profiling of somatostatin receptor subtype expression by quantitative PCR and correlation with clinicopathological features in pancreatic endocrine tumors

Predictive Factors for Resistant Disease with Medical/Radiologic/Liver-Directed Anti-Tumor Treatments in Patients with Advanced Pancreatic Neuroendocrine Neoplasms: Recent Advances and Controversies

Simple Summary

Tumor resistance, both primary and acquired, is leading to increased complexity in the nonsurgical treatment of patients with advanced panNENs, which would be greatly helped by reliable prognostic/predictive factors. The importance in identifying resistance is being contributed to by the increased array of possible treatments available for treating resistant advanced disease; the variable clinical course as well as response to any given treatment approach of patients within one staging or grading system, the advances in imaging which are providing increasing promising results/parameters that correlate with grading/outcome/resistance, the increased understanding of the molecular pathogenesis providing promising prognostic markers, all of which can contribute to selecting the best treatment to overcome resistance disease. Several factors have been identified that have prognostic/predictive value for identifying development resistant disease and affecting overall survival (OS)/PFS with various nonsurgical treatments of patients with advanced panNENs. Prognostic factors identified for patients with advanced panNENs for both OS/PFSs include various clinically-related factors (clinical, laboratory/biological markers, imaging, treatment-related factors), pathological factors (histological, classification, grading) and molecular factors. Particularly important prognostic factors for the different treatment modalities studies are the recent grading systems. Most prognostic factors for each treatment modality for OS/PFS are not specific for a given treatment option. These advances have generated several controversies and new unanswered questions, particularly those related to their possible role in predicting the possible sequence of different anti-tumor treatments in patients with different presentations. Each of these areas is reviewed in this paper.

Abstract

Purpose: Recent advances in the diagnosis, management and nonsurgical treatment of patients with advanced pancreatic neuroendocrine neoplasms (panNENs) have led to an emerging need for sensitive and useful prognostic factors for predicting responses/survival. Areas covered: The predictive value of a number of reported prognostic factors including clinically-related factors (clinical/laboratory/imaging/treatment-related factors), pathological factors (histological/classification/grading), and molecular factors, on therapeutic outcomes of anti-tumor medical therapies with molecular targeting agents (everolimus/sunitinib/somatostatin analogues), chemotherapy, radiological therapy with peptide receptor radionuclide therapy, or liver-directed therapies (embolization/chemoembolization/radio-embolization (SIRTs)) are reviewed. Recent findings in each of these areas, as well as remaining controversies and uncertainties, are discussed in detail, particularly from the viewpoint of treatment sequencing. Conclusions: The recent increase in the number of available therapeutic agents for the nonsurgical treatment of patients with advanced panNENs have raised the importance of prognostic factors predictive for therapeutic outcomes of each treatment option. The establishment of sensitive and useful prognostic markers will have a significant impact on optimal treatment selection, as well as in tailoring the therapeutic sequence, and for maximizing the survival benefit of each individual patient. In the paper, the progress in this area, as well as the controversies/uncertainties, are reviewed.

Role of Somatostatin Receptor in Pancreatic Neuroendocrine Tumor Development, Diagnosis, and Therapy

Pancreatic neuroendocrine tumors (pNETs) are rare and part of the diverse family of neuroendocrine neoplasms (NENs). Somatostatin receptors (SSTRs), which are widely expressed in NENs, are G-protein coupled receptors that can be activated by somatostatins or its synthetic analogs. Therefore, SSTRs have been widely researched as a diagnostic marker and therapeutic target in pNETs. A large number of studies have demonstrated the clinical significance of SSTRs in pNETs. In this review, relevant literature has been appraised to summarize the most recent empirical evidence addressing the clinical significance of SSTRs in pNETs. Overall, these studies have shown that SSTRs have great value in the diagnosis, treatment, and prognostic prediction of pNETs; however, further research is still necessary.

Effects of novel somatostatin-dopamine chimeric drugs in 2D and 3D cell culture models of neuroendocrine tumors

Control of symptoms related to hormonal hypersecretion by functioning neuroendocrine tumors (NETs) is challenging. New therapeutic options are required. Since novel in vitro tumor models seem to better mimic the tumor in vivo conditions, we aimed to study the effect of somatostatin and dopamine receptor agonists (octreotide and cabergoline, respectively) and novel somatostatin-dopamine chimeric multi-receptor drugs (BIM-065, BIM-23A760) using 2D (monolayer) and 3D (spheroids) cultures. Dose-response studies in 2D and 3D human pancreatic NET cell cultures (BON-1 and QGP-1) were performed under serum-containing and serum-deprived conditions. Cell proliferation, somatostatin and dopamine receptor expression (SSTs and D2R), apoptosis, lactate dehydrogenase, as well as serotonin and chromogranin A (CgA) release were assessed. The following results were obtained. 3D cultures of BON-1/QGP-1 allowed better cell survival than 2D cultures in serum-deprived conditions. SSTs and D2R mRNA levels were higher in the 3D model vs 2D model. Octreotide/cabergoline/BIM-065/BIM-23A760 treatment did not affect cell growth or spheroid size. In BON-1 2D-cultures, only BIM-23A760 significantly inhibited CgA release -this effect being more pronounced in 3D cultures. In BON-1 2D cultures, cabergoline/BIM-065/BIM-23A760 treatment decreased serotonin release (maximal effect up to 40%), being this effect again more potent in 3D cultures (up to 67% inhibition; with BIM-23A760 having the most potent effects). In QGP-1, cabergoline/BIM-065 treatment decreased serotonin release only in the 3D model. In conclusion, cultures of NET 3D spheroids represent a promising method for evaluating cell proliferation and secretion in NET cell-line models. Compared to 2D models, 3D models grow relatively serum independent. In 3D model, SST-D2R multi-receptor targeting drugs inhibit CgA and serotonin secretion, but not NET cell growth.

Clinicopathological characteristics of non-functioning cystic pancreatic neuroendocrine tumors

BACKGROUND/OBJECTIVES

The biological features of cystic pancreatic neuroendocrine tumors (PNETs) remain unclear. The aim of this study was to clarify the clinicopathological characteristics of non-functioning PNETs (NF-PNETs) with a cystic component.

METHODS

The medical records of 75 patients with NF-PNETs who had undergone resection in our institution were retrospectively reviewed. Clinicopathological factors were compared between PNETs with and without a cystic component. Expression of somatostatin 2 receptor (SSTR-2) was also analyzed.

RESULTS

Cystic PNETs were diagnosed in 14 patients (19%). The proportion of men was significantly higher for cystic than solid PNETs (79% vs. 44%, P < 0.05) and cystic PNETs were significantly larger than solid PNETs (25 mm vs. 17 mm, P < 0.01). However, there were no significant differences in the prevalence of lymph node metastases (14% vs. 10%, P = 0.64), hepatic metastasis (7% vs. 3%, P = 0.54), or disease-free survival rate (both 86%, P = 0.29) between PNETs with and without a cystic component. SSTR-2 expression was more frequently observed in PNETs with a cystic component than in those without (100% vs. 70%, P < 0.01).

CONCLUSIONS

Although cystic PNETs were larger upon diagnosis than solid PNETs in this study, prognosis after surgical resection did not differ significantly between these types of PNET. Somatostatin receptor scintigraphy and somatostatin analogues may be more useful for diagnosing and treating cystic PNETs, respectively.

Somatostatin receptor expression related to TP53 and RB1 alterations in pancreatic and extrapancreatic neuroendocrine neoplasms with a Ki67-index above 20

Somatostatin receptor 2A expression is a feature of well-differentiated neuroendocrine neoplasms and is important for their diagnosis and therapy. Little is known about somatostatin receptor 2A expression in poorly differentiated neuroendocrine neoplasms in relation to TP53 and RB1 status and how these features may contribute to the separation of well from poorly differentiated neuroendocrine neoplasms with a proliferation index above 20%. This study investigates the expression of somatostatin receptors, p53 and Rb1, and TP53 alterations in pancreatic and extrapancreatic well and poorly differentiated neuroendocrine neoplasms (Ki67-index >20%). Thirty-seven poorly differentiated neuroendocrine neoplasms of pancreatic (n=12) and extrapancreatic origin (n=25) as well as 10 well-differentiated neuroendocrine neoplasms of the pancreas (n=9) and rectum (n=1) with a Ki67-index >20% were immunostained for synaptophysin, chromogranin A, Ki67, CD56, p53, Rb1, ATRX, DAXX, progesterone receptor, somatostatin receptor 2A, somatostatin receptor 5, and cytokeratin 20, and sequenced for TP53, exons 5-9. Somatostatin receptor 2A was positive in 6/37 of poorly differentiated and in 8/10 of well-differentiated neuroendocrine neoplasms. One well-differentiated and two poorly differentiated neuroendocrine neoplasms expressed somatostatin receptor 5. Abnormal nuclear p53 and Rb1 staining was found in 29/37 and 22/37 poorly differentiated neuroendocrine neoplasms, respectively, whereas all well-differentiated neuroendocrine neoplasms showed normal p53 and Rb1 expression. TP53 gene alterations were restricted to poorly differentiated neuroendocrine neoplasms (24/34) and correlated well with p53 expression. All cases were progesterone receptor negative. Somatostatin receptor 2A expression is not limited to well-differentiated neuroendocrine neoplasms but also occurs in 16% of poorly differentiated neuroendocrine neoplasms from various sites. Most poorly differentiated neuroendocrine neoplasms are characterized by TP53 alterations and Rb1 loss, usually in the absence of somatostatin receptor 2A expression. In the pancreas, these criteria contribute to separate well-differentiated neuroendocrine neoplasms with a Ki67-index above 20% from poorly differentiated neuroendocrine neoplasms.

Antisecretory Effects of Chimeric Somatostatin/Dopamine Receptor Ligands on Gastroenteropancreatic Neuroendocrine Tumors

OBJECTIVES

The recent finding that gastroenteropancreatic neuroendocrine tumors expressed the dopaminergic D2 receptor in addition to somatostatin (sst) receptors suggested that multiple targeting approaches might decrease hormone hypersecretion more effectively than sst agonists alone.

METHODS

To test this hypothesis, (i) we measured the expression of sst receptor type 2 (sst2 receptor) and D2 receptor in 11 gastroenteropancreatic neuroendocrine tumors and (ii) we compared the ability of lanreotide, cabergoline, their combination, and sst/D2 chimeric ligands to decrease chromogranin A (CgA), gastrin, or serotonin release in primary cultures derived from these tumors.

RESULTS

Moderate to high positivity was observed for sst2 receptor and D2 receptor, the latter being more expressed in pancreatic tumors. Lanreotide decreased CgA secretion in all cultures, but only 3 tumors responded to cabergoline. No additivity was observed in lanreotide. BIM 23A781 decreased CgA release to the same extent as lanreotide, whereas the other chimeric ligands were less efficient. However, BIM 23A781 was 50 times less potent than lanreotide. Similar patterns were found for gastrin or serotonin.

CONCLUSION

No improvement was brought by the sst/D2 combination or chimeric ligands. Factors that underlie these tissue-specific differences remain to be elucidated.

Association Between Somatostatin Receptor Expression and Clinical Outcomes in Neuroendocrine Tumors

OBJECTIVE

Somatostatin receptors (SSTRs), products of gene superfamily SSTR1-5, are commonly expressed in neuroendocrine tumors (NETs). Somatostatin analogs (SSAs) bind to SSTRs and are used as therapeutic agents in patients with advanced NETs. We hypothesized that tumor SSTR expression status would be associated with clinical outcomes in NET.

METHODS

Expression of the 5 SSTRs was evaluated by immunohistochemistry, using tissue microarrays comprising 173 primary NETs, 24 matched metastases, and 22 metastatic NETs from 195 patients. Cox proportional hazards regression analysis was used to assess the association of SSTR expression status (high vs low) with clinical outcomes, adjusting for potential confounders.

RESULTS

High expression of SSTR2 was associated with longer overall survival (OS) in the cohort overall (multivariate hazard ratio, 0.42; 95% confidence interval, 0.21-0.84; P = 0.013). In a subgroup of patients with metastatic small intestine NET treated with SSAs and evaluable for progression, SSTR2 expression was associated with both longer progression-free survival (PFS) and OS. No associations with PFS or OS were observed with expression of other SSTRs.

CONCLUSIONS

Our study demonstrated that expression of SSTR2, but not other SSTRs, is associated with longer OS. In patients treated with SSAs, expression of SSTR2 is associated with longer PFS survival.

Epidrug-induced upregulation of functional somatostatin type 2 receptors in human pancreatic neuroendocrine tumor cells

Somatostatin receptors are a pivotal target for treatment of pancreatic neuroendocrine tumors (pNET), either with somatostatin analogues (SSA) or radiolabeled SSA. The highest affinity target for the most commonly used SSA is the somatostatin receptor type 2 (sst₂ ). An important factor that may complicate treatment efficacy, is the variable number of receptors expressed on pNETs. Gene expression is subject to complex regulation, in which epigenetics has a central role. In this study we explored the possible role of epigenetic modifications in the variations in sst₂ expression levels in two human pNET cell lines, BON-1 and QGP-1. We found upregulation of sst₂ mRNA after treatment with the epidrugs 5-aza-2'-deoxycytidine (5-aza-dC) and valproic acid (VPA), an increased uptake of radiolabeled octreotide, as well as increased sensitivity to the SSA octreotide in functional cAMP inhibition. At epigenetic level we observed low methylation levels of the sst₂ gene promoter region irrespective of expression. Activating histone mark H3K9Ac can be regulated with epidrug treatment, with an angle of effect corresponding to the effect on mRNA expression. Repressive histone mark H3K27me3 is not regulated by either 5-aza-dC or VPA. We conclude that epidrug treatment, in particular with combined 5-aza-dC and VPA treatment, might hold promise for improving and adding to current SSA treatment strategies of patients with pNETs.

Ki-67 prognostic and therapeutic decision driven marker for pancreatic neuroendocrine neoplasms (PNENs): A systematic review

BACKGROUND

We systematically evaluate the current evidence regarding Ki-67 as a prognostic factor in pancreatic neuroendocrine neoplasms to evaluate the differences of this marker in primary tumors and in distant metastases as well as the values of Ki-67 obtained by fine needle aspiration and by histology.

METHODS

The literature search was carried out using the MEDLINE/PubMed database, and only papers published in the last 10 years were selected.

RESULTS

The pancreatic tissue suitable for Ki-67 evaluation was obtained from surgical specimens in the majority of the studies. There was a concordance of 83% between preoperative and postoperative Ki-67 evaluation. Pooling the data of the studies which compared the Ki-67 values obtained in both cytological and surgical specimens, we found that they were not related. The assessment of Ki-67 was manual in the majority of the papers considered for this review. In order to eliminate manual counting, several imaging methods have been developed but none of them are routinely used at present. Twenty-two studies also explored the role of Ki-67 utilized as a prognostic marker for pancreatic neuroendocrine neoplasms and the majority of them showed that Ki-67 is a good prognostic marker of disease progression. Three studies explored the Ki-67 value in metastatic sites and one study demonstrated that, in metachronous and synchronous liver metastases, there was no significant variation in the index of proliferation.

CONCLUSIONS

Ki-67 is a reliable prognostic marker for pancreatic neuroendocrine neoplasms.

mRNA expression of somatostatin receptor subtypes SSTR-2, SSTR-3, and SSTR-5 and its significance in pancreatic cancer

Background

The aim of this study is to investigate the expressions of somatostatin receptor (SSTR), SSTR-2, SSTR-3, and SSTR-5, in pancreatic tissue and non-cancerous tissue and elucidate their clinical significance.

Methods

The expression of somatostatin receptor subtypes SSTR-2, SSTR-3, and SSTR-5 messenger RNA (mRNA) in 108 cases of cancer tissue and adjacent tissue in patients with pancreatic cancer was detected by reverse transcriptase polymerase chain reaction (RT-PCR). Expression of SSTR-2, SSTR-3, and SSTR-5 mRNA was evaluated after specimens were taken from selected patients who underwent surgical resection by Whipple’s operation. We speculated the clinical significance of the expression of somatostatin receptor (SSTR) subtype genes SSTR-2, SSTR-3, and SSTR-5 in pancreatic tissue and non-cancerous tissue and further elucidated their clinical significance.

Results

The expression rates of SSTR-2 mRNA in cancer and adjacent tissue of 108 patients with pancreatic cancer were 81.5% (88/108) and 97.2% (105/108), respectively; SSTR-3 mRNA expression rates were 69.4% (75/108) and 55.6% (60/108). SSTR-5 mRNA expression rates were 13.0% (14/108) and 18.5% (20/108).

Conclusion

We propose that SSTR-2 plays an important role in clinical implications for patients with pancreatic cancer undergoing somatostatin or its analog therapy.

Electronic supplementary material

The online version of this article (doi:10.1186/s12957-015-0467-z) contains supplementary material, which is available to authorized users.

Somatostatin receptor 2 and 5 expressions in gastroenteropancreatic neuroendocrine tumors in Turkey

BACKGROUND

Gastroenteropancreatic neuroendocrine tumors (GNs) are slow growing and although their incidence has increased in recent years, they are relatively rarely seen. Somatostatin analogues are used in the treatment of GNs that express somatostatin receptor (SR). We aimed to investigate the expression of SR2 and SR5 in GNs.

MATERIALS AND METHODS

In this study the expression of SR2 and SR5 was investigated immunohistochemically in 49 cases (26 males, 23 females) diagnosed and graded with GN according to the World Health Organization classification 2010.

RESULTS

The percentage of SR2 staining was 91.0% in grade 1, 82.8% in grade 2 and 100% in grade 3. On the other hand, the percentage of SR5 staining was 81.8% % in grade 1, 60.0% in grade 2 and 0% in grade 3. According to the tumor localization, the percentages of SR2 expression were as follows: pancreas 85.7%, stomach 100%, small bowel 70%, appendix 85.7% and rectum 100%. The percentages of SR5 expression were: pancreas 61,9%, stomach 37.5%, small bowel 70%, appendix 71.5% and rectum 66.6%. There was a significant negative correlation between ki67 percentage and SR5 expression (r=-0.341, p=0.016).

CONCLUSIONS

In this study, GNs were found to highly express SR2 and SR5. Although the expression of SR2 and SR5 changed according to tumor localization, the expression of SR2 was higher than the expression of SR5 in GN. There was a significant negative correlation between ki67 and SR5. Accordingly, SR5 may be a prognostic indicator of GN.

The usefulness of endoscopic ultrasound-guided fine-needle aspiration for the diagnosis of pancreatic neuroendocrine tumors based on the World Health Organization classification

BACKGROUND

We assessed the controversial topic of using 22-gauge needles in endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) for the diagnosis and evaluation of Ki67 labeling indices (Ki67LI) of pancreatic neuroendocrine tumors (pNET).

METHODS

Thirty-eight patients with pNET who underwent EUS-FNA between January 1, 2008 and December 31, 2012 were enrolled in this study. When available, the Ki67LI and WHO classifications obtained by EUS-FNA and surgical resection were compared.

RESULTS

EUS-FNA with a 22-gauge needle acquired sufficient histological sample to correctly diagnose pNET in 35 cases (92.1%). Both EUS-FNA and surgical histological specimens were available for 19 cases, and grading classes of the 2 procedures were consistent in 17 cases (89.5%) according to the WHO classification based on the Ki67LI. Tumor size was associated with a difference in the Ki67LI between the 2 procedures, although the Ki67LI was almost completely consistent for tumors less than 18 mm in size.

CONCLUSIONS

EUS-FNA with a 22-gauge needle is a safe and highly accurate technique for the diagnosis of pNET. There was a clear correlation between the Ki67LI of histological specimens acquired by EUS-FNA and surgery. EUS-FNA with a 22-gauge needle is useful to predict the WHO classification of pNET.

Pancreatic neuroendocrine tumors: pathologic and molecular characteristics

Pancreatic neuroendocrine neoplasms include mainly well-differentiated neuroendocrine tumors but also rare poorly differentiated neuroendocrine carcinomas. Molecular mechanisms underlying pancreatic neuroendocrine tumorigenesis have recently been elucidated. While alterations in the chromatin remodeling and PI3K/Akt/mTOR pathways are present in most well-differentiated pancreatic neuroendocrine tumors, mutations in TP53 and RB may contribute to the development of pancreatic poorly differentiated neuroendocrine carcinomas. With these discoveries, new molecular targeted therapies have become available and show promise in some patients with pancreatic well-differentiated neuroendocrine tumor.

Gastric inhibitory polypeptide receptor (GIPR) is a promising target for imaging and therapy in neuroendocrine tumors

BACKGROUND

Ligands binding the somatostatin receptor type 2 (SSTR2) are useful for imaging and treatment of neuroendocrine tumors (NETs), but not all tumors express high levels of these receptors. The aim of this study was to evaluate gene expression of new therapeutic targets in NETs relative to SSTR2.

METHODS

RNA was extracted from 103 primary small bowel and pancreatic NETs, matched normal tissue, and 123 metastases. Expression of 12 candidate genes was measured by quantitative polymerase chain reaction normalized to internal controls; candidate gene expression was compared with SSTR2.

RESULTS

Relative to normal tissue, primary NET expression of SSTR2, GPR98, BRS3, GIPR, GRM1, and OPRK1 were increased by 3, 8, 13, 13, 17, and 20-fold, respectively. Similar changes were found in metastases. Although most candidate genes showed lesser absolute expressions than SSTR2, absolute GIPR expression was closest to SSTR2 (mean dCT 3.6 vs. 2.7, P = .01). Absolute OPRK1 and OXTR expression varied greatly by primary tumor type and was close to SSTR2 in small bowel NETs but not pancreatic NETs.

CONCLUSION

Compared with the current treatment standard SSTR2, GIPR has only somewhat lesser absolute gene expression in tumor tissue but much lesser expression in normal tissue, making it a promising new target for NET imaging and therapy.

Overexpression of membrane proteins in primary and metastatic gastrointestinal neuroendocrine tumors

BACKGROUND

Small bowel and pancreatic neuroendocrine tumors (SBNETs and PNETs) are rare tumors whose incidence is increasing. Drugs targeting the somatostatin receptor are beneficial in these tumors. To identify additional cell-surface targets, we recently found receptors and membrane proteins with gene expression significantly different from adjacent normal tissues in a small number of primary SBNETs and PNETs. We set out to validate these expression differences in a large group of primary neuroendocrine tumors and to determine whether they are present in corresponding liver and lymph node metastases.

METHODS

Primary SBNETs and PNETs, normal tissue, nodal, and liver metastases were collected and mRNA expression of six target genes was determined by quantitative PCR. Expression was normalized to GAPDH and POLR2A internal controls, and differences as compared to normal tissue were assessed by Welch's t test.

RESULTS

Gene expression was determined in 45 primary PNETs with 20 nodal and 17 liver metastases, and 51 SBNETs with 50 nodal and 29 liver metastases. Compared to normal tissue, the oxytocin receptor (OXTR) showed significant overexpression in both primary and metastatic SBNETs and PNETs. Significant overexpression was observed for MUC13 and MEP1B in PNET primary tumors, and for GPR113 in primary SBNETs and their metastases. SCTR and ADORA1 were significantly underexpressed in PNETs and their metastases. OXTR protein expression was confirmed by immunohistochemistry.

CONCLUSIONS

OXTR is significantly overexpressed relative to normal tissue in primary SBNETs and PNETs, and this overexpression is present in their liver and lymph node metastases, making OXTR a promising target for imaging and therapeutic interventions.

Characterization of neuroendocrine tumors of the pancreas by real-time quantitative polymerase chain reaction. A methodological approach

The aim of this study was to assess the suitability of using real-time quantitative PCR (RT-qPCR) to characterize neuroendocrine (NE) tumors of the pancreas. For a series of tumors, we evaluated several genes of interest, and the data were matched with the "classical" immunohistochemical (IHC) features. In 21 cases, we extracted RNA from formalin-fixed paraffin-embedded (FFPE) blocks, and in nine cases, we also extracted RNA from fresh-frozen tissue. The RT-qPCR procedure was performed using two sets of customized arrays. The test using the first set, covering 96 genes of interest, was focused on assessing the feasibility of the procedure, and the results were used to select 18 genes indicative of NE differentiation, clinical behavior, and therapeutic responsiveness for use in the second set of arrays. Threshold cycle (Ct) values were used to calculate the fold-changes in gene expression using the 2-∆∆Ct method. Statistical procedures were used to analyze the results, which were matched with the IHC and follow-up data. Material from fresh-frozen samples performed better in terms of the level of amplification, but acceptable and concordant results were also obtained from FFPE samples. In addition, high concordance was observed between the mRNA and protein expression levels of somatostatin receptor type 2A (R = 0.52, p = 0.016). Genes associated with NE differentiation, as well as the gastrin-releasing peptide receptor and O-6-methylguanine-DNA methyltransferase genes, were underexpressed, whereas angiogenesis-associated markers (CDH13 and SLIT2) were overexpressed in tissues with malignant behavior. The RT-qPCR procedure is practical and feasible in economic terms for the characterization of NE tumors of the pancreas and can complement morphological and IHC-based evaluations. Thus, the results of the RT-qPCR procedure might offer an objective basis for therapeutic choices.

EUS-FNA for pancreatic neuroendocrine tumors: a tertiary cancer center experience

OBJECTIVES

Pancreatic neuroendocrine tumors (PNET) are fairly uncommon. Recent data highlight the importance of EUS in diagnosis of PNET. With this background, we decided to review our experience from a tertiary cancer center with regard to the presentation and clinical features of PNET and the diagnostic utility of EUS-FNA in this scenario.

METHODS

We identified patients who underwent EUS at our institution between January 1st 2001 and December 31st 2009 for a suspected PNET. Data on clinical features, cross-sectional imaging findings, EUS findings, and cytology results were collected.

RESULTS

A total of 81 patients were referred for EUS-FNA for a suspected PNET. Mean age was 58.1 years. There were 41 (50.6%) males. PNET was found incidentally in 38 (46.9%) patients. Computed tomography scanning identified a pancreatic mass in 72 out of 79 (91.1%) cases. Mean diameter of the largest lesion seen on EUS was 27.5 mm (range: 6.9-80 mm). The most common site (34; 42%) was the head of the pancreas. EUS-FNA correctly confirmed a PNET in 73 out of 81 cases with diagnostic accuracy of 90.1%. Seven (8.6%) out of 81 patients had functional lesions, including three gastrinomas and four insulinomas. Liver metastases were found in 31 out of 81 (38.3%) cases. Of the 31 patients with liver metastasis, the mean diameter of lesions on EUS was 33.9 mm compared with 23.5 mm in patients without liver metastasis (P = 0.005).

CONCLUSION

EUS-FNA is a reliable modality for further characterization of suspected lesions and for establishing a tissue diagnosis. The occurrence of complications of EUS-FNA in this setting is low. Non-functional PNET are more frequently encountered than functional PNET.