The octreotide suppression test and [111In-DTPA-D-Phe1]-octreotide scintigraphy in neuroendocrine tumours correlate with responsiveness to somatostatin analogue treatment

Role of biomarker tests for diagnosis of neuroendocrine tumours

Neuroendocrine tumours (NETs) are neoplasms that arise from neuroendocrine cells. Neuroendocrine cells and their tumours can secrete a wide range of amines and polypeptide hormones into the systemic circulation. This feature has triggered widespread investigation into circulating biomarkers for the diagnosis of NETs as well as for the prediction of the biological behaviour of tumour cells. Classic examples of circulating biomarkers for gastroenteropancreatic NETs include chromogranin A, neuron-specific enolase and pancreatic polypeptide as well as hormones that elicit clinical syndromes, such as serotonin and its metabolites, insulin, glucagon and gastrin. Biomarker metrics of general markers for diagnosing all gastroenteropancreatic NET subtypes are limited, but specific hormonal measurements can be of diagnostic value in select cases. In the past decade, methods for detecting circulating transcripts and tumour cells have been developed to improve the diagnosis of patients with NETs. Concurrently, modern scanning techniques and superior radiotracers for functional imaging have markedly expanded the options for clinicians dealing with NETs. Here, we review the latest research on biomarkers in the NET field to provide clinicians with a comprehensive overview of relevant diagnostic biomarkers that can be implemented in dedicated situations.

Circulating biomarkers in neuroendocrine tumors of the enteropancreatic tract: application to diagnosis, monitoring disease, and as prognostic indicators

Neuroendocrine tumors (NETs) are difficult to diagnose. Their symptoms may be vague or intermittent, and are frequently associated with much more common diseases; many of the tumors may be asymptomatic. Therefore, diagnosis can be delayed for some years. Because most NETs are secretory, the measurement of circulating biomarkers is helpful not only for diagnosis but also for assessing tumor response to treatment, monitoring disease progression, and use as prognostic indicators.

Plasma chromogranin A response to octreotide test: prognostic value for clinical outcome in endocrine digestive tumors

OBJECTIVES

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) expressing somatostatin receptors may be treated with somatostatin analogs (SSAs). Selection criteria are a positive Octreoscan or a >50% hormone level decrease after octreotide subcutaneous (s.c.) injection (octreotide test) (OT). Plasma chromogranin A (CgA) is the best general GEP-NET marker, but data on CgA response to OT are scanty. Thus, we evaluated whether plasma CgA response to OT could predict the clinical response to SSAs.

METHODS

At diagnosis, 38 GEP-NET patients received octreotide 200 microg s.c., with plasma CgA determination at 0, 3, and 6 h. Long-term SSA treatment was then given by monitoring symptomatic, biochemical, and objective responses, and survival.

RESULTS

Basal plasma CgA levels were significantly higher in patients with functioning than non-functioning tumors (median (range): 220 (18-2,230) vs. 46 (25-8,610) U/l, P=0.03) and in those with than without metastases (171 (18-8,610) vs. 43 (28-220) U/l, P=0.04). CgA levels significantly correlated with WHO classification, clinical TNM staging, and Ki-67 proliferative index. After OT, CgA levels decreased from 146 (18-8,610) to 61 (10-8,535) U/l (basal and nadir values), P<0.001. In patients responsive to OT, a successful objective response occurred in 21/31 patients (68%). Successful symptomatic response occurred in 13/18 patients (72%), biochemical response in 25/31 (81%), and objective response in 21/31 (68%). In the remaining seven unresponsive cases, with CgA decrement <30%, disease progressed to death in six (86%). Median survival from enrollment was 48 months (6-138) in responsive and 6 (6-30) in unresponsive patients (P=0.0005).

CONCLUSIONS

In GEP-NETs, plasma CgA is a reliable marker, and a >30% decrease after OT has a relevant prognostic meaning allowing the identification of the subgroup of patients most likely to be responsive to chronic SSAs.

Circulating markers for endocrine tumours of the gastroenteropancreatic tract

The diffuse endocrine system (DES) includes a wide range of secretory cells that may be the source of tumours. Gastroenteropancreatic endocrine (GEP) tumours arising within the DES secrete a variety of peptides and amines that are found in the circulation and are responsible for the syndromes associated with these tumours. In this review, the most common tumours of the GEP tract are outlined and the circulating products of these tumours identified. Where differential diagnosis is difficult these points are addressed. The peptides most commonly secreted by GEP neuroendocrine tumours are identified and described and their biological activities are discussed. Current methods available for measurement of these peptides are described. Attention is drawn towards molecular specificity where appropriate, as many pancreatic and gut peptides fall within families which show considerable homology, such as the tachykinin family or the glucagon family. Other peptides such as gastrin circulate in multiple molecular forms. This homology and diversity may cause difficulty in the interpretation of peptide measurements in the clinical situation if assays are not specific.

MEN1 family with a novel frameshift mutation

Multiple endocrine neoplasm type 1 (MEN1) syndrome predisposes to the development of endocrine and non-endocrine tumors with an autosomal dominant pattern of inheritance. Different mutations have been found throughout the gene with a variable phenotype expression. The proband, a Caucasian man, was admitted to our department in 2001, at the age of 51 because of a 1-yr history of diarrhoea and hypertension. He reported a previous intestinal resection for bowel occlusion with a histological diagnosis of unspecified mesenchymal neoplasia. He had also undergone a left adrenalectomy for a large nonfunctioning adrenal adenoma. Subsequently, he had suffered from gastralgia and melena; a gastroduodenoscopy showed an erosive gastritis. His family history was negative for endocrine disorders. On physical examination, multiple abdominal cutaneous lipomas and facial angiofibromas were observed. Biochemical screening revealed a primary hyperparathyroidism and an increase in circulating levels of PRL, chromogranin-A, gastrin and glucagon. The whole body computed tomography (CT) scan, the 111In-octreotide scan and the pituitary magnetic resonance imaging (MRI) did not reveal any abnormality. The presence of small neuroendocrine tumors was suspected by a positron emission tomography uptake in the epigastric region. The endoscopic ultrasound revealed a pancreatic lesion sized 1.1 cm that is under evaluation. Direct DNA sequencing analysis of the proband MEN1 gene revealed the 579delG frameshift mutation in the exon 3. The genetic screening of the family revealed the same mutation in 3 out of 5 offspring. The biochemical screening revealed some features of the MEN1 syndrome in all three of them. In conclusion, a novel frameshift MEN1 mutation was found in kindred with an apparently negative family history. Our experience confirms that MEN1 syndrome is a complex and underestimated condition, unless specifically investigated by trained specialists.

Endocrine tumours of the gastrointestinal tract. Biotherapy for metastatic endocrine tumours

Somatostatin analogues have been the mainstay of symptomatic management of patients with neuroendocrine tumours (NETs) for two decades with the main mechanism of action being inhibition of peptide release. Evidence base for interferon use is perhaps less clear. It may contribute to symptom control by abrogating peptide release, and there is some evidence that it has an anti-proliferative action. Combination of somatostatin analogues and interferon provides symptom control, mainly by effecting a reduction in the amount of circulating, physiologically active, peptide hormones. Treatment can also provide disease stabilisation in a proportion of patients. In a minority of patients treatment may lead to partial response.

Teste agudo com octreotide subcutâneo como preditor de resposta ao tratamento com octreotide LAR®

Os análogos da somatostatina são muito utilizados no tratamento da acromegalia. Com o objetivo de determinar o valor do teste agudo (TA) com octreotide subcutâneo (SC) como preditor da resposta ao tratamento com octreotide LAR®, analisamos os dados de 20 pacientes. Para o TA, amostras de sangue foram colhidas antes e duas horas após a administração de octreotide SC para a dosagem de GH. Os níveis de GH antes e após o TA foram 21,9 (2,3-143,4) e 3,1ng/mL (0,3-61,3), respectivamente. Foi considerado controle de doença: GH< 2,5ng/mL e IGF-I normal em algum momento durante o tratamento. A sensibilidade, especificidade e os valores preditivos positivo e negativo do TA foram 0,9, 0,6, 0,69 e 0,86 para redução de 75% do GH no teste. Concluímos que, em nossa casuística, um decréscimo de 75% dos níveis de GH no TA teve um bom poder discriminatório entre pacientes com maior e menor chance de resposta ao tratamento.

Octreotide in insulinoma patients: efficacy on hypoglycemia, relationships with Octreoscan scintigraphy and immunostaining with anti-sst2A and anti-sst5 antibodies

OBJECTIVE

We studied the efficacy of octreotide treatment on hypoglycaemia in patients with insulinoma and its relationships with Octreoscan scintigraphy and the presence of tumoral somatostatin receptors sst2A and sst5.

DESIGN AND METHODS

17 patients with insulinoma were evaluated using (i) evaluation of blood glucose, insulin and C-peptide during a short 100 mug octreotide test in fasting patients and/or treatment over 8 days-8 months with octreotide, (ii) Octreoscan scintigraphy and (iii) immunostaining of the tumor with anti-sst2A and anti-sst5.

RESULTS

Octreotide was effective on hypoglycaemia in 10/17 patients. Octreoscan scintigraphy detected 4/17 insulinomas. sst2A receptor was detected in 7/17 insulinomas and sst5 in 15/17 insulinomas. Octreotide was effective on hypoglycaemia in those seven patients with sst2A receptor-expressing insulinoma, and in three patients with undetectable sst2A receptor and detectable sst5; it was ineffective in six patients whose tumor expressed the sst5 receptor with undetectable sst2A and in one patient with undetectable sst2A and sst5 receptor.

CONCLUSIONS

Octreotide is an effective treatment of hypoglycaemia in more than 50% of patients with insulinoma. Detection of responsive patients was better based on a positive short test with subcutaneous octreotide than on the results of Octreoscan scintigraphy. Positive anti-sst2 receptor immunostaining is associated with efficacy of octreotide treatment, but does not account for all cases of responsiveness to octreotide. Expression of sst5 receptor does not appear to explain per se the efficacy of octreotide on sst2A-negative insulinomas.

Poorly differentiated small cell neuroendocrine carcinoma localized in three different endocrine glands: response to chemotherapy and octreotide LAR

Neuroendocrine tumors represent a heterogeneous category of neoplasm, with conflicting diagnostic and therapeutic demands. We here describe the case of a 72-yr-old woman with evidence of a poorly differentiated small-cell neuroendocrine carcinoma (NEC) localized in different endocrine glands and other non-endocrine organs. In particular, a large ovarian mass, multinodular thyroid goiter, right adrenal mass, cystic liver metastases and anterior mediastinum lymph node metastasis were present. The largest thyroid nodule caused tracheal restriction and dyspnea. Diagnosis of poorly differentiated metastasized NEC of unknown origin was made on the basis of histological and immunohistochemical findings, and treatment with etoposide (100 mg/m2 in days 1, 2 and 3) and cisplatinum (45 mg/m2 in days 2 and 3) was initiated. Simultaneously, im administration of octreotide LAR 20 mg every 28 days was started, according to the presence of SS receptors at 111In-octreotide scan. Rapid improvement of dyspnea and a reduction of the largest thyroid nodule, liver metastases and adrenal mass by 50% were observed after 3 months of treatment; the dimensions remained stable thereafter, while the pericardial lymph node disappeared. In conclusion, poorly differentiated NEC of unknown primary site is a well-recognized category, usually with an aggressive behavior, rapid growth rate and wide dissemination. Median survival of these patients is 6 months if left untreated. Our patient is alive 18 months after beginning the treatment, reporting good general condition and quality of life over the whole follow-up period.

Receptor-Mediated Tumor Targeting with Radiopeptides. Part 1. General Concepts and Methods: Applications to Somatostatin Receptor-Expressing Tumors

Radiolabeled peptides have become important tools in nuclear oncology, both as diagnostics and more recently also as therapeutics. They represent a distinct sector of the molecular targeting approach, which in many areas of therapy will implement the old "magic bullet" concept by specifically directing the therapeutic agent to the site of action. In this three-part review, we present a comprehensive overview of the literature on receptor-mediated tumor targeting with the different radiopeptides currently studied. Part I summarizes the general concepts and methods of targeting, the selection of radioisotopes, chelators, and the criteria of peptide ligand development. Then, the >400 studies on the application to somatostatin/somatostatin-release inhibiting factor receptor-mediated tumor localization and treatment will be reviewed, demonstrating that peptide radiopharmaceuticals have gained an important position in clinical medicine.

Minute gastric carcinoid tumor with regional lymph node metastasis: A case report and review of literature

We have encountered an unusual case of gastric carcinoid tumor. Gastroscopic examination of this 32-year-old male patient showed a smooth protrusion at the greater curvature of the gastric body with a central depression, identified by subsequent biopsy as carcinoma. The patient had a normal serum gastrin level and was negative for anti-parietal cell antibody. Histological examination of the resected gastric tissues showed that the tumor was a carcinoid, 0.3 cm × 0.3 cm in size with only one regional lymph node metastasis. We reviewed the pathogenesis, clinical presentation, diagnosis and treatment of gastric carcinoids and raise the possibility of being a lymph vessel-related metastasis even for a minute carcinoid tumor. Sentinel lymph node biopsy is recommended for surgery of minute carcinoid tumors.

Malignant bronchial carcinoid tumor metastatic to the pituitary in a thyroid carcinoma patient: successful treatment with surgery, radiotherapy and somatostatin analog

A carcinoid pituitary metastasis is very rare, and is reported scarcely in a few patients. We describe an unusual case of metastatic atypical bronchial carcinoid to the anterior pituitary gland in a 47-year-old male who presented with bitemporal hemianopsia and hypopituitarism. His primary bronchial carcinoid was resected two years previously. Foci of metastatic papillary thyroid carcinoma were also identified in the lung resected for the bronchial carcinoid. He thereby underwent total thyroidectomy followed by radioiodine ablative treatment. Transsphenoidal partial removal of the suprasellar mass was performed, and atypical carcinoid metastasis was identified. He received conventional fractionated sellar radiotherapy, which was supplemented with octreotide (Sandostatin LAR) injections following a positive pituitary uptake on octreotide scan. This treatment suppressed his elevated 5-HIAA urinary excretion to a normal level. His vision has returned to normal and the pituitary mass diminished in size.

The clinical management of neuroendocrine tumors with long-acting repeatable (LAR) octreotide: comparison with standard subcutaneous octreotide therapy

Neuroendocrine tumors are rare, occurring in less than 1% of the population. They are divided clinically into functionally active or non-active tumors. Functionally active tumors produce a variety of substances (mainly peptides or serotonin) that are responsible for symptoms and sometimes can lead to the death of the patient independently from tumor proliferation. The most important compounds that can control symptoms in these patients are somatostatin analogs. Native somatostatin is not suitable for long-term clinical application due to its short half-life. Therefore, synthetic drugs were developed with improved pharmacokinetic characteristics. The best-characterized analog, octreotide, has been successfully applied to patients with functioning tumors. Octreotide can ameliorate symptoms in 30%-70% of the patients, mainly through a direct inhibitory effect on hormone production from the tumors. There is little or no effect on tumor growth during octreotide therapy; clinical responses were recorded in only 10%-30% of the patients. Recently, significant improvement in the management of the disease has been demonstrated with long-acting repeatable (LAR) octreotide. This new formulation requires only one monthly intramuscolar injection, and shows better acceptability and patient compliance to therapy. Data available to date show superimposable results of both standard octreotide and LAR octreotide in controlling symptoms, lowering hormone and tumor marker levels, and in reducing tumor growth. The availability of long-acting molecules have permitted the exploration of high-dose therapy in increasing tumor shrinkage and prolonging survival. Although there is a clear dose-response trend, the published data are not conclusive and further investigations are needed. The possible lack of cross-resistance between LAR octreotide and a different analog, Lanreotide, is a very stimulating finding and this might lead to the development of new therapeutical strategies in the management of neuroendocrine tumors.

Recent advances in systemic therapy for gastrointestinal neuroendocrine tumors

Neuroendocrine tumors of the gastrointestinal tract are rare tumors which can be classified as amine precursor uptake and decarboxylation tumors (APU-Domas). Although the majority of clinically apparent tumors are malignant, they are frequently slow growing. Despite this characteristic, they may generate disabling hormonal syndromes requiring aggressive treatment to achieve palliation. Recent advances in understanding the pathophysiology of these tumors has led to better medical therapy with chemotherapeutic agents, somatostatin analogues, and biologic therapies. This review will update the recent efforts in systemic therapies of the gastrointestinal neuroendocrine tumors.