NANETS treatment guidelines: well-differentiated neuroendocrine tumors of the stomach and pancreas

Neuroendocrine liver metastases: Contributions of endoscopy and surgery to primary tumor search

Neuroendocrine tumors (NETs) are diagnosed with increasing frequency and patients often present with liver metastases at the time of diagnosis. Apart from treatment of the metastases, resection of the primary tumor at an early phase is recommended to prevent complications, although it may be difficult to locate, especially in patients with functionally inactive NETs. Small and multifocal tumors in the jejunum and ileum represent a particular challenge. Primary hepatic neuroendocrine carcinoma is extremely rare and is diagnosed only after exclusion of other primary tumors. Therefore, some uncertainty may remain, as small non-hepatic primary tumors may escape detection. Diagnostic work-up in these patients includes biochemical assays and imaging modalities (also comprising specific techniques of scintigraphy and positron emission tomography). This editorial highlights the contributions of endoscopy and operative exploration to the search for the primary tumor. Besides esophago-gastro-duodenoscopy, endoscopic ultrasonography, colonoscopy and bronchoscopy, special endoscopic techniques such as balloon enteroscopy or capsule endoscopy are used with growing experience. Compared with balloon enteroscopy, capsule endoscopy is non-invasive and better tolerated, but it cannot localize a lesion precisely and does not allow biopsy or removal of lesions. Before proceeding to surgery, a discussion of the findings by a tumor board should be a standard procedure. Improvements in diagnostic tools have created new perspectives for the detection of obscure primary tumors in patients with neuroendocrine liver metastases, and these searches are best coordinated by a multidisciplinary team.

Incidental detection of pancreatic neuroendocrine tumors: an analysis of incidence and outcomes

BACKGROUND

Pancreatic neuroendocrine tumors (NETs) are increasingly discovered incidentally during radiologic or endoscopic examinations. The frequency of incidental detection is unknown. It is also unclear whether patients with incidentally discovered, early-stage, asymptomatic tumors should be treated similarly to patients who present with tumor-related symptoms.

METHODS

Patients with nonmetastatic pancreatic NETs treated at the H. Lee Moffitt Cancer Center between 1999 and 2010 were assigned a stage (I-III) on the basis of the new American Joint Committee on Cancer classification. The frequency of incidentally diagnosed tumors was evaluated and stratified by stage. Progression-free survival was measured by log rank testing to compare patients with incidentally detected versus symptomatic tumors. Multivariate analysis was performed controlling for other prognostic factors including tumor stage, grade, and location, and patient age.

RESULTS

Among 143 patients with nonmetastatic pancreatic NETs, 56 patients (40%) had tumors that were discovered incidentally. Most stage I tumors (55%) were incidental. The 5-year progression-free survival rate was 86% for incidentally diagnosed tumors, versus 59% for symptomatic tumors (P = 0.007). On multivariate analysis, incidental detection of tumors was the strongest prognostic factor for progression.

CONCLUSIONS

A sizable fraction of patients with early-stage pancreatic NETs are diagnosed incidentally during evaluations for other conditions or unrelated symptoms. This study highlights the necessity of developing guidelines for management of patients with incidentally discovered early-stage tumors.

[Medicinal therapy of metastasized neuroendocrine tumors of the gastroenteropancreatic system.]

Neuroendocrine neoplasms of the gastroenteropancreatic system are classified according to the WHO classification system 2010 into neuroendocrine tumors (NET) and neuroendocrine carcinomas (NEC). The proliferation index Ki-67 and the grading of NETs is essential for the prognosis and therapy plan. Also NET tumor biology and therapeutic options may differ depending on the primary NET tumor location. Palliative therapy of inoperable NETs involves local ablative methods in cases of primary liver metastasis, peptide receptor radionuclide therapy (PRRT) in NETs expressing somatostatin receptors and different options for medicinal therapy. This manuscript reviews the current role of biotherapy with somatostatin analogues and interferon-alpha for symptom and tumor control. In addition conventional chemotherapy regimens and novel molecular targeted therapeutic options, such as sunitinib or everolimus in NET of the pancreas are reviewed. Possible therapeutic algorithms are discussed.

New treatment strategies in advanced neuroendocrine tumours

Malignant well-differentiated neuroendocrine tumours of the pancreas and the gastrointestinal tract are rare and clinically challenging heterogeneous neoplasms. This review focuses on neuroendocrine tumours grade 1 and grade 2 (new WHO classification 2010), in comparison to the neuroendocrine tumours grade 3 group, corresponding to poorly differentiated neuroendocrine carcinomas. Surgical resection of the primary and metastases remains the only curative treatment, however many patients with neuroendocrine tumours are diagnosed once unresectable metastases have occurred; management of functioning syndromes with somatostatin analogues remains the priority. Pasireotide, a new somatostatin analogue, is currently undergoing evaluation for carcinoid syndrome. Treatment options for advanced neuroendocrine tumours differ from pancreatic gastrointestinal tract neuroendocrine tumours: (a) in pancreatic neuroendocrine tumours, streptozotocin-based chemotherapies are challenged by other cytotoxic agents (dacarbazine, temozolomide and oxaliplatin); two randomized, placebo-controlled phase III studies have demonstrated that everolimus and sunitinib significantly improved progression-free-survival; (b) in midgut neuroendocrine tumours, octreotide improved time-to-progression in patients with a low proliferation index and low liver burden; preliminary data suggesting efficacy of bevacizumab are still to be confirmed; the effect of everolimus associated with octreotide was almost significant on progression-free-survival in a phase III trial. Liver-directed therapies are effective in both tumour types. New techniques of embolization need further evaluation and must be formally compared to other therapies. Finally, peptide receptor radionuclide therapy has shown promising activity in non-comparative studies in advanced neuroendocrine tumours.

Contemporary management of nonfunctioning pancreatic neuroendocrine tumors

BACKGROUND

This article reviews the current literature and recommendations pertaining to the management of nonfunctioning pancreatic neuroendocrine tumors.

DISCUSSION

In recent years the detection of nonfunctioning pancreatic neuroendocrine tumors has increased coincident with the increased use of cross-sectional imaging and is now thought to represent 2-10% of all pancreatic tumors. Improved understanding of the biology and behavior of these heterogeneous tumors is needed to guide therapy. The present review discusses diagnostics, therapeutics including emerging molecular analytics, and surveillance recommendations.

Neuroendocrine tumors of the pancreas

PURPOSE OF REVIEW

Pancreatic neuroendocrine tumors (PNETs) are rare tumors, with an incidence of one per 100, 000 individuals per year, and they account for 1-2% of all pancreatic neoplasms. PNETs are a heterogeneous group with varying clinical presentation, tumor biology and prognosis. This article reviews the current diagnostic strategy and treatment armamentarium for PNETs. Special attention is paid to recent and ongoing developments in treatment, particularly with regards to multimodality treatment and newer systemic therapies for unresectable disease.

RECENT FINDINGS

There has been significant progress in the genetic understanding of hereditary syndromes in regards to PNETs, as well as in the diagnosis and treatment of resectable and nonresectable PNETs. Whereas surgical therapy remains the most advisable therapy for resectable neuroendocrine tumors of the pancreas, there have been significant recent advances in systemic therapy for those with unresectable disease. Results from recent clinical trials examining mammalian target of rapamycin inhibitors and tyrosine kinase inhibitors for unresectable disease are promising in expanding treatment options for metastatic PNETs.

SUMMARY

Neuroendocrine tumors of the pancreas are a heterogeneous group of tumors with varying clinical presentation, tumor biology and prognosis. Clinicians must be aware of the variety of manifestations of this disease, as well as the role of systemic chemotherapy in treatment of unresectable disease.

Gastroenteropancreatic neuroendocrine tumors: new insights in the diagnosis and therapy

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are relatively rare and heterogenous malignancies. Recent advances in histopathological classification according to the anatomical site of origin, proliferation rate, and extend of the disease have created a valid and powerful tool for the prognostic stratification of GEP-NETs. Chromogranin A is still the best available marker used for the biochemical confirmation of these tumors, but new more sensitive markers are urgently required. Although scintigraphy with (111)In-octreotide has widely been applied for the localization and staging of GEP-NETs, newer imaging modalities based on the functional characteristics of these tumors are evolving aiming not only to facilitate the diagnosis but also prognosis and evaluation of treatment. Somatostatin receptors are the primary therapeutic targets through somatostatin analogs and peptide receptor radionuclide therapy (PRRT) producing symptomatic, biochemical and to a lesser extent antiproliferative effects. Due to the relatively limited and erratic response to chemotherapy, new molecular targeted therapies exploiting some of the biological properties of GEP-NETs such as increased vascularity and inhibition of pathways involved in downstream signal transduction have evolved. Some of these therapies, the mTOR inhibitor everolimus and the tyrosine kinase inhibitor sunitinib, have been recently validated in phase III studies producing practice changing outcomes. In addition, two oral chemotherapeutic agents temozolomide and capecitabine, show promising effects and may replace streptozotocin-based regimens whereas combination therapies with the angiogenesis inhibitor bevacizumab are being investigated. Although progression free survival is used as a feasible primary end point due to the long survival of patients even in the presence of extensive disease prolongation of overall survival following the introduction of new therapies needs to be established.

Quality of clinical trials in gastroenteropancreatic neuroendocrine tumours

BACKGROUND

The heterogeneity of neuroendocrine tumours (NETs) makes interpretation of clinical trials in this disease challenging. Our aim was to review the quality of treatment trials in NETs in order to inform the design and reporting of future studies.

METHODS

We identified studies by searching MEDLINE. We considered all phase II and III trials of systemic antineoplastic treatments published between 2000 and 2011. Information on trial design, study population, end points, statistical considerations and results was abstracted from each article using a standardized form.

RESULTS

Seven phase III and 39 phase II trials were identified. The make-up of the study population was variable: only 24% of trials included patients with one type of tumour (pancreatic NET or carcinoid tumour), 41% included patients with both tumour types, and 35% of trials included other endocrine cancers. Disease progression at baseline was often not reported and was documented for all patients in 22% of the trials. The functional status of the tumour, tumour differentiation, and Ki67 index were reported in 35, 43, and 15% of trials, respectively. The primary end point was clearly defined in 72% of trials. Identifiable statistical design, and predefined sample size were reported in 74 and 61% of trials, respectively. Conflicts of interest and study sponsorship were reported in 46 and 85% of trials.

CONCLUSIONS

The quality of the design and reporting of phase II/III NET trials, as described in other cancers, is poor. Future trials should include more homogenous patient populations while adhering to rigorous selection, reporting and interpretation of population and trial parameters.

A renaissance in therapeutic options for pancreatic neuroendocrine tumors

The field of pancreatic neuroendocrine tumors (NETs) has seen a remarkable renaissance in recent years with exponential increases in published research, clinical trials, and U.S. Food and Drug Administration (FDA)-approved treatments. Surgical resection remains the foundation for management of locoregional disease. However, for patients with advanced disease, novel therapeutic options have emerged. Two separate randomized placebo-controlled studies have shown prolonged progression-free survival (PFS) with everolimus or sunitinib. Future studies are designed to answer questions about the role of somatostatin analogs as antiproliferative agents, combinations of biologic therapies, and new cytotoxic chemotherapy backbones.

A multimodal approach to the management of neuroendocrine tumour liver metastases

Neuroendocrine tumours (NETs) are often indolent malignancies that commonly present with metastatic disease in the liver. Surgical, locoregional, and systemic treatment modalities are reviewed. A multidisciplinary approach to patient care is suggested to ensure all therapeutic options explored.

Surgical management of pancreatic neuroendocrine tumors

This study outlines the surgical management and clinicopathological findings of pancreatic neuroendocrine tumors (P-NETs). There are various surgical options, such as enucleation of the tumor, spleen-preserving distal pancreatectomy, distal pancreatectomy with splenectomy, pancreatoduodenectomy, and duodenum-preserving pancreas head resection. Lymph node dissection is performed for malignant cases. New guidelines and classifications have been proposed and are now being used in clinical practice. However, there are still no clear indications for organ-preserving pancreatic resection or lymph node dissection. Hepatectomy is the first choice for liver metastases of well-differentiated neuroendocrine carcinoma without extrahepatic metastases. On the other hand, cisplatin-based combination therapy is performed as first-line chemotherapy for metastatic poorly differentiated neuroendocrine carcinoma. Other treatment options are radiofrequency ablation, transarterial chemoembolization/embolization, and liver transplantation. Systematic chemotherapy and biotherapy, such as that with somatostatin analogue and interferon-α, are used for recurrence after surgery. The precise surgical techniques for enucleation of the tumor and spleen-preserving distal pancreatectomy are described.

New therapeutic options for metastatic malignant insulinomas

Insulinomas are the most common, functioning, pancreatic neuroendocrine tumours. The great majority (>90%) of insulinomas are nonmetastatic at presentation and can be surgically cured. The <10% patients with distant (liver-bone) metastases have a median survival of < 2 years. Everolimus and sunitinib have been recently introduced as targeted therapies for metastatic pancreatic neuroendocrine tumours. An additional advantage of everolimus in the treatment of patients with metastatic insulinomas is its capability to increase blood glucose levels. Peptide receptor radiotherapy using radiolabelled somatostatin analogues has also been shown to be successful in controlling tumour growth of metastatic pancreatic neuroendocrine tumours. In patients with metastatic insulinomas, this therapeutic modality was also effective in controlling hypoglycaemia, even in the presence of tumour regrowth. With the introduction of these new therapeutic modalities, the therapeutic arsenal for the 'tailor-made' approach of patients with metastatic insulinomas is further expanded.

Comparison of clinicopathologic factors in 122 patients with resected pancreatic and ileal neuroendocrine tumors from a single institution

BACKGROUND

Recent population-based studies have demonstrated significant differences in outcome between patients with pancreatic and ileal neuroendocrine tumors. The objective of this study was to examine the clinicopathologic differences between ileal and pancreatic neuroendocrine tumors following resection.

METHODS

A retrospective chart review was performed and data on clinicopathologic variables, biochemical markers, and follow-up of patients with resected ileal (INETs) and pancreatic (PNETs) neuroendocrine tumors were collected. The t test or analysis of variance (ANOVA) was used to compare means. Survival analysis was performed using the Kaplan-Meier method.

RESULTS

Between 1998 and 2010, 122 patients with PNETs and INETs were explored (70 PNETs and 52 INETs). Several variables were found to be significantly different between patients in both groups. INETs were more often associated with flushing (44 vs. 14%; P < 0.001) and diarrhea (63 vs. 16%; P < 0.001) and were more often associated with elevation in preoperative serum levels of pancreastatin (88 vs. 42%; P < 0.001), chromogranin A (78 vs. 54%; P = 0.036), and serotonin (90 vs. 43%; P < 0.001). INETs more frequently had vascular invasion on pathology (96 vs. 60%; P < 0.001), and presented more often with nodal and/or distant metastases (77 vs. 37%; P < 0.001). There was no significant difference in overall survival between patients in both groups.

CONCLUSION

In this series, patients with INETs presented with a more advanced stage of disease compared with PNETs, had higher preoperative levels of 3 markers, and were more often symptomatic. Despite these factors, there was no significant difference in overall survival between patients with these 2 tumor types.

Conundrums and Caveats in Neuroendocrine Tumors of the Pancreas

Pancreatic neuroendocrine tumors (Pan-NETs) are the second most common epithelial neoplasm of the pancreas after ductal adenocarcinoma. They can be clinically defined as functional, nonfunctional, and hereditary. This review addresses typical and atypical pathologic features of Pan-NETs, with a focus on practical issues involved in differential diagnosis, immunohistochemical work-up, intraoperative frozen section interpretation, sources of diagnostic errors, and classification. The diagnosis of a Pan-NET requires analysis of all available clinical and radiographic information and pathologic characteristics of the tumor, and it is crucial to understand the clinical impact of the pathologic interpretation.

[Pharmacologic therapy for neuroendocrine tumours]

Neuroendocrine tumours are heterogeneous and rare malignancies arising from endocrine cells located in various anatomical locations. Neuroendocrine tumours can be functional and may produce a wide variety of mediators, however, the majority of neuroendocrine tumours do not produce biologically active hormones (non-functioning tumours). On the basis of their pathological and biological characteristics they can be well differentiated as low malignant and poorly differentiated highly malignant tumours. In the case of the advanced low malignant tumours the application of somatostatin analogues not only may control symptoms but they also have direct anti-tumour effect. The use of higher doses of somatostatin analogues or new subtype selective agonists, and chimeric or pan-somatostatin analogues will probably improve the clinical management of the patients who fail to respond to standard somatostatin analogue treatment. Data show that somatostatin analogues and interferon have a synergistic effect. The currently used chemotherapy in progressive neuroendocrine tumors is mainly devoted to poorly differentiated tumours, but also to well differentiated carcinomas which are either not eligible or resistant to other therapies. However, the new anti-tumoural agents, could eventually replace these old recipes in the near future. Clinical trials show that telozomide with capecitabine result in more favorable toxic profile and higher and longer response rate in the case of well-differentiated tumours. Targeted therapy became a new possibility in neuroendocrine tumours too. The monoclonal antibody bevacizumab, which affects the vascular endothelial growth factor receptors, has beneficial effects both in monotherapies and in combination with somatostatin analogues or with oxaliplatine and capecitabine. Recently, the low molecular multikinase inhibitor, sunitinib has demonstrated efficacy in pancreas neuroendocrine tumors, which was proven in a phase 3 trial. The mammalian target of the rapamycin inhibitor everolimus, currently investigated in phase 3 trials, was also efficient in the same subtype. Further trials are needed to determine that in the case of other types of neuroendocrine tumours which targeted therapy could be efficient. Radioisotope-labeled peptide receptor therapy with ¹³¹I-MIBG, ⁹⁰Y-DOTA-TOC or ¹⁷⁷Lu-DOTA-TOC may offer a highly effective option for patients with progressive and advanced stage of neuroendocrine tumours. The purpose of this review is to review and analyze data available regarding contemporary chemotherapeutic management of neuroendocrine tumours in order to determine which therapy should be applied in the therapeutic arsenal.

A clinical perspective on gastric neuroendocrine neoplasia

The incidence of gastric neuroendocrine tumors (NETs) has increased exponentially based on widespread use of endoscopy and a greater pathological awareness of the condition. A key concern is the potential association with hypergastrinemia induced by proton pump inhibitor administration. Previous confusion regarding diagnosis and therapy has been diminished by a series of international consensus statements defining the biology and management strategies for the disease. Overall, gastric NETs are categorized as well-differentiated or poorly differentiated neoplasms. Well-differentiated gastric NETs are enterochromaffin-like (ECL) cell tumors subclassified into three types based on their relationship to gastrin, a key regulator of ECL cell neoplastic transformation. The treatment of type 1 and type 2 tumors depends on the size and invasiveness of the tumor, whereas type 3 tumors and poorly differentiated neuroendocrine carcinomas warrant aggressive surgical resection. The disease-specific 5-year survival ranges from about 95% in type 1 gastric carcinoids to about 25% in poorly differentiated gastric NECs. Elucidation of the precise biology of a gastric NET is critical to diagnosis and delineation of a type-specific management strategy.