Chromogranins as diagnostic and prognostic markers in neuroendocrine tumours

Inflammation Related to Obesity in the Etiopathogenesis of Gastroenteropancreatic Neuroendocrine Neoplasms

Gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) are rare neoplasms, which, due to their heterogeneous nature, non-specific symptoms, and lack of specific tumor markers pose many diagnostic and clinical challenges. In recent years, the effectiveness of GEP-NEN diagnosis has increased, which is probably associated with the greater availability of diagnostic tests and the cooperation of many experienced specialists in various scientific disciplines. In addition to the possible genetic etiology, the cause of GEP-NET development is not fully understood. Inflammation and obesity are known risks that contribute to the development of many diseases. Chronic inflammation accompanying obesity affects the hormonal balance and cell proliferation and causes the impairment of the immune system function, leading to neoplastic transformation. This review explores the role of inflammation and obesity in GEP-NETs. The exact mechanisms inducing tumor growth are unknown; however, the profile of inflammatory factors released in the GEP-NET tumor microenvironment is responsible for the progression or inhibition of tumor growth. Both the excess of adipose tissue and the impaired function of the immune system affect not only the initiation of cancer but also reduce the comfort and lifetime of patients.

Surgical treatment of liver metastases in patients with neuroendocrine tumors

Liver metastases occur in 75% to 80% of patients with neuroendocrine tumors (NETs), and are considered significant adverse prognostic indicators. Management of NETs liver metastases is challenging and requires aggressive therapy. Currently, there are many therapeutic options for metastatic NETs. However, there is considerable controversy regarding the optimal management. Although complete surgical resection remains the optimal therapy, a variety of other minimally invasive surgical and medical options are available, this includes thermal ablative techniques (e.g., radiofrequency ablation, microwave ablation, cryotherapy), embolization using transcatheter embolization, chemoembolization, or radioembolization, and medical therapy (e.g., chemotherapy, biotherapy with somatostatin analogues and interferon). Currently there is no evidence-based data directly comparing surgical versus alternative liver-directed treatment options. An aggressive surgical approach, coupled with additional liver-directed procedures is often recommended as it extends the overall survival. Optimal patient care should be directed by a multidisciplinary team to assure that all treatment options are explored for decision-making while treating this aggressive disease.

Hepatic arterial embolization in patients with neuroendocrine tumors

Liver metastases occur in 46-93% of patients with neuroendocrine neoplasms (NENs). Presence and extension of liver metastases are considered important prognostic factors, as they may significantly impair the patient's quality of life, because of either tumor bulk or hormonal hypersecretion. Therapies for NEN liver metastases include surgical resection, liver transplantation, chemotherapy and biotherapy. Surgery is the gold standard for curative therapy, but in most of NEN patients with liver metastases, when surgery can not be applied, minimally invasive therapeutic approaches are adopted. They include trans-arterial embolization (TAE), trans-arterial chemoembolization (TACE), radiofrequency thermal ablation and new emerging techniques.TAE is based on selective infusion of particles in the branch of the hepatic artery supplying the tumor lesions. The goal of TAE is to occlude tumor blood vessels resulting in ischemia and necrosis. Many reports have shown that TAE can reduce tumor size and hormone output, resulting in palliation of symptoms without the use of cytotoxic drugs, resulting in better tolerability. This review will focus on TAE performance and safety in NEN patients with liver metastases.

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.

Chromogranin A as potential target for immunotherapy of malignant pheochromocytoma

Currently, no effective treatment for malignant pheochromocytoma exists. The aim of our study was to investigate the role of chromogranin A (CgA) as a specific target molecule for immunotherapy in a murine model for pheochromocytoma. Six amino acid-modified and non-modified CgA peptides were used for dendritic cell vaccination. Altogether, 50 mice received two different CgA vaccination protocols; another 20 animals served as controls. In vitro tetramer analyses revealed large increases of CgA-specific cytotoxic T cells (CTL) in CgA-treated mice. Tumors of exogenous applied pheochromocytoma cells showed an extensive infiltration by CD8+ T cells. In vitro, CTL of CgA-treated mice exhibited strong MHC I restricted lysis capacities towards pheochromocytoma cells. Importantly, these mice showed strongly diminished outgrowth of liver tumors of applied pheochromocytoma cells. Our data clearly demonstrate that CgA peptide-based immunotherapy induces a cytotoxic immune response in experimental pheochromocytoma, indicating potential for therapeutic applications in patients with malignant pheochromocytoma.

Multimodal management of neuroendocrine liver metastases

BACKGROUND

The incidence of neuroendocrine tumours (NET) has increased over the past three decades. Hepatic metastases which occur in up to 75% of NET patients significantly worsen their prognosis. New imaging techniques with increasing sensitivity enabling tumour detection at an early stage have been developed. The treatment encompasses a panel of surgical and non-surgical modalities.

METHODS

This article reviews the published literature related to management of hepatic neuroendocrine metastases.

RESULTS

Abdominal computer tomography, magnetic resonance tomography and somatostatin receptor scintigraphy are widely accepted imaging modalities. Hepatic resection is the only potentially curative treatment. Liver transplantation is justified in highly selected patients. Liver-directed interventional techniques and locally ablative measures offer effective palliation. Promising novel therapeutic options offering targeted approaches are under evaluation.

CONCLUSIONS

The treatment of neuroendocrine liver metastases still needs to be standardized. Management in centres of expertise should be strongly encouraged in order to enable a multidisciplinary approach and personalized treatment. Development of molecular prognostic factors to select treatment according to patient risk should be attempted.

Identifying tumor antigens in endocrine malignancies

Tumor antigens are surface molecules that are mostly cancer specific, often overexpressed and recognized by the immune system. Therefore, identifying tumor antigens is of key importance for developing new immunotherapies for incurable cancers. For endocrine malignancies, several different tumor-associated antigens have been described, including polypeptide hormones and/or vesicle-associated antigens in Th1-mediated autoimmune diseases. Other antigens have been identified by screening tumor DNA libraries. Furthermore, vaccination studies in humans and animal models have revealed a tumor-antigen-specific immunity and clinical responses with reduced tumor size. Here, we provide an overview of the recent progress achieved in identifying tumor antigens and predict how this knowledge can be used in the future for developing anti-tumor vaccinations.

Chronic subacute bowel obstruction caused by carcinoid tumour misdiagnosed as irritable bowel syndrome: a case report

Background

Carcinoid tumours are well-differentiated neuroendocrine tumours with secretory properties. Although fairly rare, they are the most common malignancy seen to affect the distal small bowel. Presentation is often non-specific with symptoms mimicking those of irritable bowel syndrome. Given this, the condition is often diagnosed late following disease progression, by which time the prognosis is poor.

Case presentation

A 74 year old Caucasian lady presented with a two week history of loose stools, nausea and one episode of vomiting. This sub-acute presentation occurred on a background of a four year history of intermittent abdominal pain and bloating, previously diagnosed as irritable bowel syndrome. CT scans identified dilated loops of small bowel proximal to a spiculated mass in the region of the terminal ileum. This ileal lesion was removed at laparotomy and identified as a carcinoid tumour.

Conclusion

This case highlights the issue of misdiagnosis of intestinal malignancy as the benign condition of irritable bowel syndrome. There have been several other references to this happenstance in the literature, and the problem is reflected in the percentage of patients with widespread disease at the time of diagnosis. Prognosis in this condition can be dramatically improved with early diagnosis, and surgical management at this stage is often curative. For this reason it is imperative to keep this differential diagnosis in the back of one's mind when assessing patients presenting with symptoms of intermittent partial bowel obstruction. The clinical presentation of this tumour, along with investigation and management of these cases, is discussed here.

Concordance between results of somatostatin receptor scintigraphy with 111In-DOTA-DPhe 1-Tyr 3-octreotide and chromogranin A assay in patients with neuroendocrine tumours

PURPOSE

Somatostatin receptor scintigraphy (SRS) and chromogranin A (CgA) assay have successfully been implemented in the clinical work-up and management of neuroendocrine tumour (NET) patients. However, there is still a lack of studies comparing results in these patients. Our aim was to compare directly in NET patients SRS and CgA assay results with special regard to tumour features such as grade of malignancy, primary origin, disease extent and function.

METHODS

One hundred twenty consecutive patients with histological confirmed NETs were investigated with (111)In-DOTA-DPhe(1)-Tyr(3)-octreotide ((111)In-DOTA-TOC) SRS and CgA immunoradiometric assay. Tumours were classified by cell characteristics [well-differentiated NETs, well-differentiated neuroendocrine carcinomas, poorly differentiated neuroendocrine carcinomas (PDNECs)], primary origin (foregut, midgut, hindgut, undetermined), disease extent (limited disease, metastases, primary tumour and metastases) and functionality (secretory, nonsecretory).

RESULTS

SRS was positive in 107 (89%) patients; CgA levels were increased in 95 (79%) patients. Overall, concordance between SRS and CgA results was found in 84 patients. Positive SRS but normal CgA level were found in 24 patients, with higher prevalence (p<0.05) in patients with nonsecretory tumours. Conversely, negative SRS but CgA level increased were seen in 12 patients, with higher proportion (p<0.05) in patients with PDNECs and tumours of hindgut origin.

CONCLUSIONS

Overall, (111)In-DOTA-TOC SRS proved to be more sensitive than CgA in NETs patients. Tumour differentiation, disease extent and presence of liver metastases impact both SRS and CgA results, whereas nonsecretory activity is a negative predictor of only CgA increase. PDNECs and hindgut origin of tumours predispose to discrepancies with negative SRS but increased CgA levels.

Plasma chromogranin A or urine fractionated metanephrines follow-up testing improves the diagnostic accuracy of plasma fractionated metanephrines for pheochromocytoma

CONTEXT

The initial diagnosis of pheochromocytoma relies on plasma fractionated metanephrines levels. Normal levels exclude pheochromocytoma, but positive tests have a low positive predictive value due to the disease's rarity.

OBJECTIVES

The objective of the study was to evaluate three approaches to distinguish between true-positive and false-positive tests: 1) increased cutoff for plasma fractionated metanephrines, 2) measurement of serum/plasma chromogranin A (CGA), and 3) urine fractionated metanephrine testing.

DESIGN

We studied retrospectively all Mayo Clinic patients with positive plasma fractionated metanephrine tests over a 15-month period and determined their final diagnosis based on histology, imaging, additional biochemical tests, and more than 1 yr follow-up. For a subgroup, urine fractionated metanephrine results were available. All original plasma samples were retested for CGA.

RESULTS

Of 140 patients, 40 had a chromaffin tumor confirmed and 100 excluded, indicating a positive predictive value of plasma fractionated metanephrines of 28.6%. Increasing the threshold for a positive test improved specificity to 98% but missed eight cases (20%). Incorporation of urine fractionated metanephrine testing as follow-up test achieved 80% specificity and 91% sensitivity. The corresponding figures for CGA were 71 and 87% for all patients and 89 and 87% when patients taking proton pump inhibitors were excluded.

CONCLUSIONS

Unless plasma fractionated metanephrines levels are elevated more than 4-fold above the upper limit of normal, patients with a positive plasma fractionated metanephrines test should be evaluated with urine fractionated metanephrines and serum/plasma CGA assays before being subjected to imaging or invasive diagnostic tests.

Prospective study of the ability of serial measurements of serum chromogranin A and gastrin to detect changes in tumor burden in patients with gastrinomas

BACKGROUND

Assessment of tumor burden changes is essential for the management of patients with neuroendocrine gastrointestinal (GI) tumors. Chromogranin A (CgA) is a tumor marker for such tumors; however, to the authors' knowledge, there is little information on whether serial assessments can assess changes in tumor burden. In this prospective study of patients with gastrinomas, serial changes in serum CgA levels were compared with changes in levels of the specific tumor marker gastrin to determine whether they reflected changes in tumor burden.

METHODS

In 72 consecutive patients, the mean CgA and gastrin levels from three determinations were measured on each visit. Changes in markers were correlated with changes in tumor burden determined by imaging. By assessing daily changes, significance changes in CgA and gastrin levels were determined.

RESULTS

During 103 follow-up visits (mean, 9.6 months), an increased tumor size occurred in 25% of patients, no change occurred in 62% of patients, and a decrease occurred in 13% of patients. In patients who had increasing tumor size, CgA levels increased numerically in 77% of patients, gastrin levels increased in 54% of patients, and the increases were significant in 60-80% of patients. In patients who had tumor stabilization, CgA levels in 63% of patients and gastrin levels in 73% of patients did not show a significant change. Decreased tumor size postresection showed a significant decrease in CgA and gastrin levels in all patients. The sensitivity of CgA and gastrin was as follows: sensitivity for detecting an increase, 62% for CgA and 31% for gastrin; sensitivity for detecting no change, 42% for CgA and 75% for gastrin; and sensitivity for detecting a decrease in tumor size, 85% for CgA and 85% for gastrin. The specificity varied from 53% to 99% for CgA and from 49% to 93% for gastrin.

CONCLUSIONS

In patients with gastrinomas, serum CgA and gastrin levels varied considerably from day to day, and this must be taken into consideration. Both markers had low sensitivity and specificity for detecting tumor increases and stabilization. For large tumor decreases postresection, both markers had high sensitivity and specificity. The current results suggest that these markers do not have sufficient sensitivity to replace serial imaging studies for detecting important smaller changes in tumor burden in patients with gastrinomas.

Catecholaminergic pathways, chromaffin cells, and human disease

Recent studies demonstrate major effects of adrenal medullary and catecholaminergic pathways on a wide variety of normal physiologic and regulatory events. Alterations in these pathways, involving changes in catecholamines or in proteins and peptides costored and coreleased with catecholamines, may lead to profound changes in autonomic, cardiovascular, neuroendocrine, metabolic, nociceptive, and immune function. These findings have important implications for a variety of human disease states. In addition, molecules associated with catecholaminergic function may provide novel diagnostic and therapeutic strategies for human disease and suggest specific genetic loci as important and fruitful targets for further genetic and pharmacogenetic studies.