Cell biology, clinicopathological profile, and classification of gastro-enteropancreatic endocrine tumors

BRAF/MEK inhibitors for BRAF V600E-mutant cancers in non-approved setting: a case series

The management of cancer has been traditionally dependent on the primary tumour type and specific histologic subtypes. Recently, the introduction of molecular profiling tools and its increasing use in clinical practice has facilitated the emergence of novel genomically driven treatment options within the standard of care landscape as well as in the clinical trial setting. One such aberration is mutation in v-Raf murine sarcoma viral oncogene homolog B (BRAF), which results in hyperactivation of RAS-RAF-MEK-ERK signaling in the Mitogen-activated protein kinases (MAPK) pathway. BRAF and Mitogen-activated protein kinase, extracellular signal-regulated kinase kinase (MEK) inhibitors, although being currently approved for melanoma, non-small cell lung cancer (NSCLC) and colon cancer, have reported activity across other various cancers harbouring BRAF aberrations. It has been proposed that combined MEK and BRAF inhibition could overcome the acquired resistance commonly developed among patients receiving BRAF or MEK inhibitors as monotherapy. We report five cases of BRAF V600E (substitution of glutamic acid for valine in codon 600) aberrant refractory metastatic cancers treated with dual BRAF/MEK combination inhibitor therapy leading to an excellent clinical and radiological response and protracted duration of disease control.

Cytological Ki-67 in pancreatic endocrine tumors: a new "must"?

In the last decades, the incidence of neuroendocrine tumors (NETs) has been rising and this might be due to more awareness, improved diagnostic tools and a change in definition. The histopathological type of the tumor, its Ki-67 or MIB-1 proliferation index, size and location, as well as the age of the patient, seems to be the most important factor that affects prognosis and survival. In 2008, in one of our studies, we concluded that the cytological Ki-67 may improve the preoperative assessment of pancreatic NETs (pNETs), helping the clinician choosing the optimal therapeutical approach". Although the literature reports discordant opinions on the value of tumor proliferation markers in predicting a patient's prognosis, many studies have then reinforced the idea that Ki-67 expression in histological sections obtained from pNETs is an important predictor of their biological behaviour. The WHO classification of pNETs includes Ki-67 expression in the list of parameters (together with distant metastases, organ infiltration, dimension, angio/neuroinvasion, number of mitosis) determining the patient's prognosis. In conclusion we think that any study aimed to assess the correct biology and proliferative pattern of NETs contributes to the already known but still unclear attempt to define the correct individualized therapeutic strategy for each patient before surgery or any other therapeutic approach.

Histogenesis and natural history of gut neuroendocrine tumors: present status

Important progress has been made during the last decade in the histopathologic characterization and overall prognostic evaluation of gut neuroendocrine tumors. However, some issues like tumor histogenesis, typing, functional characterization, and preferred site of origin deserve further clarification. This is a survey of the present status of the matter outlining some of the open points. In particular, careful comparison of normal gut endocrine cell types with related endocrine tumors so far identified shows an unexplained lack of neoplasms involving upper small intestine cells like secretin, cholecystokinin, motilin, and GIP cells, as well as the equally unexplained concentration of serotonin EC cell tumors in the ileum and appendix or of somatostatin cell tumors in the duodenal papillary region, despite their wide distribution in the normal gut, not to mention gastrinomas arising in the pancreas, normally devoid of gastrin cells. Special functional (e.g., achlorhydria-driven hypergastrinemia) or pathologic (as chronic inflammation) conditions may locally influence the proliferative and differentiation state of the endocrine cells thus promoting tumor growth. Tumor histologic structure, differentiation level, and proliferative index as well as gastrointestinal wall barriers to tumor diffusion may account for most prognostic parameters, with considerable changes, however, according to the tumor type and site. Thus, further work is needed to develop tumor- and site-adjusted prognostic parameters.

Diffuse nesidioblastosis diagnosed on a Ga-68 DOTATATE positron emission tomography/computerized tomography

The authors describe a 50 days old pre-term infant with persistent hyperinsulinemic hypoglycemia of infancy in whom Ga-68 DOTATATE positron emission tomography/computerized tomography scan showed diffusely increased tracer uptake in the entire pancreas with no abnormal tracer uptake anywhere else in the body, suggestive of a diffuse variant of nesidioblastosis.

Transarterial chemoembolization with miriplatin-lipiodol emulsion for neuroendocrine metastases of the liver

Miriplatin, a cisplatin derivative with a high affinity for iodized oil, is a novel chemotherapeutic agent designed for use in the transarterial treatment of hepatocellular carcinoma. This case report describes our experience with transarterial chemoembolization (TACE) using miriplatin in 2 patients with neuroendocrine liver metastases. A 38-year-old man with multiple neuroendocrine liver metastases was treated by whole liver chemoembolization, and a 35-year-old woman with a single hepatic lesion was treated by superselective chemoembolization. No serious adverse events were noted during the interventional procedures, or during the observation period of 3 mo in either patient. Sufficient iodized oil uptake was observed in the hypervascular lesions on the unenhanced computed tomography (CT) at 7 d after the procedure. Contrast-enhanced CT obtained at 3 mo after chemoembolization revealed that all hepatic lesions were substantially reduced in size irrespective of tumor vascularity or degree of cystic degeneration, although iodized oil accumulation was only marginal for lesions with cystic degeneration. Thus, TACE with miriplatin can be a safe and effective therapeutic option for the treatment of neuroendocrine metastases of the liver.

Survival following resection of pancreatic endocrine tumors: importance of R-status and the WHO and TNM classification systems

OBJECTIVE

The aim of this study was to delineate the clinical outcomes and pathological characteristics of surgically resected endocrine tumors of the pancreas and to determine the importance of the World Health Organization (WHO) and tumor-node metastasis (TNM) classifications, resection status, and Ki-67 expression for long-term survival.

PATIENTS AND METHODS

Sixty-nine patients underwent surgical tumor resection with curative intent during 1990-2007. Hospital records were reviewed retrospectively for medical, surgical, pathological, and radiological data.

RESULTS

Forty-one patients (59%) had non-functional tumors, 28 (41%) patients had functional tumors. Thirty-seven (54%) tumors were classified as WHO group 1 and the remaining 32 as WHO group 2. There were no poorly differentiated endocrine carcinomas. The overall R0-resection rate was 68%. Patients in whom all gross tumor was resected (R0/R1) had significantly better survival compared to patients with macroscopic residual disease (R2) (p < 0.001). There was no difference in survival between patients with R0 and R1 resections. Both the WHO (p < 0.001) and the TNM (p < 0.001) classifications significantly predicted five and 10-year survival after resection of the primary tumor. Survival analysis revealed significantly better outcome for patients with tumors with Ki-67 index < 2% (p = 0.003).

CONCLUSIONS

Both WHO and TNM classifications reliably predict long-term survival in patients with resectable pancreatic endocrine tumors. R2 resection status predicted poor prognosis. R0 status did not improve prognosis relative to R1 status. Ki-67 index > 2% is a predictor of poor long-term survival.

Novel use of somatostatin receptor scintigraphy in localization of focal congenital hyperinsulinism: promising but fallible

Congenital hyperinsulinism (CHI) is the most common cause of persistent hypoglycemia in infants and children. The pre-operative differentiation of focal from diffuse forms is extremely important from the management point of view. The current methods for pre-operative differentiation are invasive. We report a patient with CHI where somatostatin receptor scintigraphy was used to diagnose CHI but with limited success. A preoperative 68gallium DOTATOC-PET scan was performed which revealed highly localized radiotracer uptake in the body of the pancreas. 80% of the pancreas including the body was resected. The clinical problems did not completely resolve after surgery. Histopathology revealed hyperplastic islet cells at the resected margin and randomly throughout the pancreas. This case highlights the use of 68gallium DOTATOC-PET scan in a patient with severe CHI. The satellite foci that were missed may be either an inherent limitation of 68Ga DOTATOC scan or an underinterpretation due to lack of expertise. This report opens up a new option of using somatostatin analogue scintigraphy for pre-operative localization of hyperplastic islet cells in patients with CHI.

Treatment of endocrine pancreatic tumors

Endocrine pancreatic tumors are rare with an incidence of 4 per million inhabitants. Most tumors are malignant except for insulinomas that usually are benign. They are slowly growing in the majority of cases but there are exceptions with rapidly progressing malignant carcinomas. Because of the rarity of these tumors large randomized trials are difficult to accomplish. However, most physicians treating these patients agree that surgery should be considered in all cases and that medical treatment with chemotherapy and biotherapy is well established for this group of patients.

Contrast-enhanced sonography of nonfunctioning pancreatic neuroendocrine tumors

OBJECTIVE

Diagnosis of malignancy and prognostic assessment continue to be problems in the management of nonfunctioning pancreatic endocrine tumors. Histologic examination is the reference standard. The aim of our study was to compare B-mode and contrast-enhanced sonographic findings regarding nonfunctioning pancreatic endocrine tumors. Signs of malignancy, such as Ki67 index and presence of hepatic metastasis, were considered.

MATERIALS AND METHODS

We retrospectively reviewed the cases of 38 consecutively registered patients with nonfunctioning pancreatic endocrine tumors evaluated with B-mode and contrast-enhanced sonography and resected. At contrast-enhanced sonography all lesions were divided into hypovascular lesions and isovascular or hypervascular lesions. On the basis of homogeneity of enhancement, lesions were classified as homogeneous and inhomogeneous. During the late phase of contrast enhancement, all solid focal hypoechoic liver lesions detected at contrast-enhanced sonography were considered hepatic metastatic lesions. Among pathologic data, grading, mitotic index, and Ki67 index were evaluated. Spearman's test was used to compare contrast-enhanced sonographic enhancement pattern with pathologic grade.

RESULTS

In the arterial phase, 24 of 38 nonfunctioning pancreatic endocrine tumors (63.1%) were hypervascular, seven (18.4%) were isovascular, and seven (18.4%) were hypovascular. Positive correlation was found between contrast-enhanced sonographic findings and Ki67 index (r(s) = 0.62; p < 0.0001). The difference between contrast-enhanced and B-mode sonography in the diagnosis of nonfunctioning pancreatic endocrine tumors was statistically significant (p < 0.05). Use of contrast-enhanced sonography increased diagnostic confidence in the detection of hepatic metastasis. The areas under the receiver operating characteristic curves were 0.916 for B-mode sonography and 1.000 for contrast-enhanced sonography (p < 0.05). There was moderate positive correlation between contrast-enhanced sonographic enhancement pattern and the presence of hepatic metastasis at diagnosis (r(s) = 0.46; p = 0.004) and between Ki67 index and the presence of hepatic metastasis (r(s) = 0.48; p = 0.0022).

CONCLUSION

The contrast-enhanced sonographic enhancement pattern of nonfunctioning pancreatic endocrine tumors has a positive correlation with Ki67 index, which is considered the most reliable independent predictor of the presence of malignancy.

Molecular imaging of neuroendocrine tumors

Molecular imaging represents tissue-specific imaging and quantification of physiologically functional and molecular events in tumors, utilizing new noninvasive imaging modalities. It combines anatomic, physiologic and metabolic information in a single imaging session. Neuroendocrine tumors (NETs) present unique features to use specific nuclear imaging, such as somatostatin receptor scintigraphy (SRS), metaiodobenzylguanidine scans and PET scanning. NETs express somatostatin receptors on tumor cells and can, thus, be visualized by ¹¹¹In-gadolinium-diethylenetriame pentaacetic acid-octreotide (OctreoScan^®), which is currently the most common scanning technique for NETs. Every patient with a NET should be subjected to SRS. Technetium-labeled somatostatin analogs are currently growing in importance. Metaiodobenzylguanidine scanning was previously the only method for detection and follow-up of NETs, but is nowadays more or less replaced by octreotide scanning. During the last decade, PET scanning has been developed for detection and follow-up of patients with NETs. It has clearly demonstrated the highest sensitivity and specificity in the range of 85-95%. It detects smaller tumors down to 3 mm, compared with SRS, which has a size limit of approximately 1 cm. ⁶⁸Ga-DOTA-octreotide will, in the future, replace SRS owing to its higher sensitivity and specificity, and also reduce the time for investigation. It will also offer the possibility to evaluate the number of somatostatin receptors in a specific tumor. In the future, PET scanning will be more readily available and less expensive, and it will be possible to study tumor biology, vascularization and gene expression in NETs with the development of new tracers.

Hepatic cytoreductive surgery for neuroendocrine cancer

Patients with gut-based metastatic neuroendocrine tumors (NET) often present late in the course of their slowly progressive disease, when cancer has extended beyond the point of reasonable expectation for surgical cure. At this stage of disease, the tumor's overwhelming hormonal production often significantly impairs the patient's quality of life. Unlike patients with other malignancies that might involve a heavy burden of hepatic metastatic disease, many patients with metastatic NET continue to live for a long time despite escalating hormone-related symptoms. This establishes the justification and rationale for cytoreduction, a noncurative surgical intervention that reduces tumor burden and hormonal burden and thereby can significantly increase symptom-free survival in the setting of an often slow but inevitable disease progression.

Nuclear imaging of neuroendocrine tumours

The diagnosis of neuroendocrine tumours (NETs) and monitoring of therapy in many patients relies mainly on morphological imaging techniques such as computed tomography (CT), ultrasound (US) and magnetic resonance imaging (MRI). However, functional imaging modalities--such as somatostatin receptor scintigraphy (SRS)--have great impact on patient management by providing tools for better staging of the disease, visualization of occult tumour, and evaluation of eligibility for somatostatin analogue treatment. Positron emission tomography (PET) using (18)F-fluoro-deoxy-glucose (FDG) is a powerful functional modality for oncological imaging. Unfortunately, FDG is not accumulated in NETs except in the case of dedifferentiated tumours and tumours with high proliferative activity. Based on the concept of amine precursor uptake and decarboxylation (APUD), the (18)F- and (11)C-labelled amine precursors L-dihydroxyphenylalanine and 5-hydroxy-L-tryptophan (5-HTP) have been utilized for PET imaging of NETs. In comparative studies of patients with a variety of NETs, (11)C5-HTP-PET proved better than CT and SRS by visualizing additional small lesions. With carbidopa premedication orally before (11)C5-HTP-PET examination the tumour uptake could be increased and the urinary radioactivity concentration considerably reduced. This concept may also be applied to (18)F-L-DOPA-PET, a method which in a limited number of studies has gained additional diagnostic information in NET patients compared to SRS and morphological imaging. (68)Ga is available from an in-house generator and has been utilized for labelling of somatostatin analogues for PET imaging of NETs with promising results in a small number of patients. However, SRS is an established functional imaging method for patients with NETs, whereas the role for PET in the clinical routine needs further evaluation in comparative studies in larger groups of patients.

Rap1/B-Raf signaling is activated in neuroendocrine tumors of the digestive tract and Raf kinase inhibition constitutes a putative therapeutic target

OBJECTIVE

Molecular pathogenesis of digestive neuroendocrine tumors (dNETs) is largely unknown. Recently, the serine-threonine kinase B-Raf was identified as an oncogene in endocrine cancer such as thyroid carcinoma. In endocrine cells, the small G-protein Rap1 stimulates mitogen-activated protein kinase (MAPK) signaling by activating B-Raf. We examined the expression of Rap1 and B-Raf in dNETs and their contribution to MAPK signaling in neuroendocrine cell lines. In addition, we explored the effect of suppressing B-Raf kinase by the recently developed inhibitor BAY43-9006 (Sorafinib) on growth, apoptosis and MAPK activation neuroendocrine cell lines.

METHODS AND RESULTS

Expression of Rap1 and B-Raf in dNETs (19 insulinomas, 15 carcinoid tumors and 10 gastrinomas) was examined by immunohistochemistry, which revealed that Rap1 and B-Raf were highly prevalent in the majority of dNETs. Overexpression of Rap1 and B-Raf activated MAPK extracellular dependent kinase (ERK) ERK-2 and ERK-dependent transcription factor Elk-1 in neuroendocrine cell lines Bon and INS-1. Suppression of B-Raf by BAY43-9006 inhibited growth and induced apoptosis in Bon and INS-1 cells. In addition, BAY43-9006 suppressed phosphorylation of MAPK ERK1/2 and its upstream kinase MEK1/2 in Bon and INS-1 cells.

CONCLUSION

These results indicate that Rap1-B-Raf signaling may contribute to pathogenesis of dNETs and provides a molecular target for treatment of dNETs.

Gastrin-releasing-peptide in neuroendorine tumours

In a substantial proportion of cases with endocrine malignant disease the primary lesion cannot be localised and the pathologist hesitates upon the origin of the tumour. Well differentiated neuroendocrine carcinomas of the small bowel can usually be identified by the strong serotonin immunoreactivity, but foregut carcinoids may also stain positive for serotonin and the differential diagnosis between the various foregut tumours may be difficult. We examined if immunostaining for gastrin-releasing-peptide (GRP) may aid in establishing the origin of an unknown neuroendocrine tumour. Tumour tissue from 79 patients (27 lung carcinoids, 4 thymic carcinoids, 4 gastric neuroendocrine tumours, 17 pancreatic well differentiated neuroendocrine carcinomas, 1 duodenal well differentiated neuroendocrine tumour and 26 well differentiated neuroendocrine carcinomas of the small bowel) were immunostained with antibodies against GRP and serotonin. Positive staining for GRP was found in 12/27 lung carcinoids. All other tumour types were consistently GRP-negative (p?<?0.0001). We conclude that immunostaining for GRP may aid in defining the origin of the tumour, and that GRP-immunoreactivity increases the suspicion of a lung carcinoid.

Treatment of advanced carcinoid tumors

PURPOSE OF REVIEW

Carcinoid tumors often present with metastatic disease. Generally, these tumors can be treated conservatively. New evidence exists, however, that stage IV disease may be better managed with more aggressive medical and surgical treatment. Headway is also being made into understanding the associated fibrosis seen with advanced disease and in better understanding signaling pathways with the hope of offering future treatment options.

RECENT FINDINGS

Recent literature has advocated for more aggressive surgical treatment of carcinoid tumors, especially in the setting of hepatic metastases and peritoneal carcinomatosis. Octreotide and lanreotide are further being described for treating metastatic carcinoids. Radiolabeled somatostatin analogues may prove to be as effective for treating carcinoids as for visualizing them. Other potential treatment modalities include pharmacologic activation of signaling pathways to control excess hormone production. Research into fibrosis - a cause of pain, bowel obstruction, retroperitoneal vascular constriction and right heart failure - has shown that serotonin and tachykinins may be the key mediators.

SUMMARY

Patients with stage IV carcinoid tumors may benefit from more aggressive surgical management and new treatment modalities. The growing body of knowledge regarding important molecular signaling pathway may lead to new medical therapies and further understanding of the sequelae of excess hormone production.

Prognostic and predictive factors in endocrine tumours

This review encompasses the diagnostic features of malignancy, the routinely observable prognostic features and the prognostic and predictive features emerging from research techniques in the principal endocrine neoplasms: pancreatic and extrapancreatic endocrine cell tumours, thyroid and parathyroid neoplasia, adrenal cortical neoplasms and adrenal and extra-adrenal paragangliomas. While each endocrine tissue has its own set of diagnostic features for malignancy, and prognostic features once a diagnosis of malignancy has been established, there are a few common themes. For several endocrine neoplasms, definite recognition of malignancy can be difficult and may depend upon frank invasive or metastatic growth at presentation. Endocrine tissues are dynamic, with hyperplastic and regressive phenomena, some of which may mimic malignancy. Even when unequivocal features of malignancy are available for observation, their distribution in tissue may be very focal, necessitating thorough sampling. The accurate documentation of routinely observable histological features interpreted in the light of current literature has not been superseded by special techniques in the statement of diagnosis or prognosis in the vast majority of endocrine neoplasms.

Nuclear medicine in the detection, staging and treatment of gastrointestinal carcinoid tumours

Carcinoid tumours belong to the family of neuroendocrine tumours with a capacity to take up and concentrate amines and precursors as well as peptides, and can thereby be detected by nuclear medicine techniques. These rare tumours are difficult to diagnose at earlier stages because of small size and multiplicity. Computed tomography (CT) and magnetic resonance imaging (MRI) are mostly of benefit for detection of larger primary tumours (1-3 cm) and liver and lymph-node metastases. A majority of carcinoid tumours express somatostatin receptors, particularly receptor type 2, and thus somatostatin receptor scintigraphy (SRS) can be used for detection and staging of carcinoid tumours. The detection rate of carcinoid tumours has been reported to be somewhere between 80 and 100% in different studies. The scintigraphy gives a good staging of the disease and detection of unexpected tumour sites, which were not determined by conventional imaging. This method also indicates content of somatostatin receptors, which might indicate efficacy of treatment with octreotide or other somatostatin analogues. Another new non-invasive technique for detection of carcinoid tumours is positron emission tomography (PET). The biological substance for study can be labelled for radioactive imaging with radionuclears, such as (11)C, (15)O and (18)F, with emission of positrons. More than 95% of patients studied displayed high tracer uptake from PET with (11)C-5HTP (5-hydroxytryptophan), which is significantly higher compared to both computer tomography and somatostatin receptor scintigraphy. MIBG has been used for decades to visualize carcinoid tumours, because MIBG is concentrated in the endocrine cells. It was initially developed to detect phaeochromocytomas of the adrenal with reported high sensitivity (87%) and specificity as high as 99%. The method can be used when other methods fail to localize carcinoid tumours and particularly when treatment with (131)I-MIBG is being considered. Tumour-targeted treatment for malignant carcinoid tumour is still investigational, but has become of significant interest with the use of radiolabelled somatostatin analogues. Since a majority of carcinoid tumours present somatostatin receptors and can therefore be visualized in vivo by using radiolabelled somatostatin analogues, it seems logical to try to target these tumours with radioactive substances, not only for visualization but also for treatment. (111)Indium-DTPA-octreotide has been used as the first tumour-targeted treatment, with rather low response rates (in the order of 10-20%) and no significant tumour shrinkage. The second radioactive analogue which has been applied in the clinic is (90)yttrium-DOTA-Tyr3-octreotide, which has given partial and complete remissions in 20-30% of patients. The most significant side-effects have been kidney dysfunction, thrombocytopenia and liver toxicity. The most recent compound is (177)lutetium-DOTA-Tyr3-octreotate, which has been applied by the Rotterdam group and has been reported to give partial remission in about 40% of the patients. In the near future, combined treatment with both (90)yttrium and (177)lutetium coupled to a somatostatin analogue might come into clinical trials. (177)Lutetium may be more effective for smaller tumours whereas (90)yttrium may be more effective for larger tumours.

Somatostatin-producing pancreatic endocrine carcinoma presented as relapsing cholangitis -- a case report

Somatostatin-producing endocrine tumors are rare neoplasms usually arising in the pancreas and duodenum and they account for less than 1% of all gastrointestinal endocrine tumors. Besides somatostatinoma syndrome, which is characterized by diabetes mellitus, steatorrhea and cholelithiasis, patients with somatostatin-producing endocrine tumors commonly complain of nonspecific symptoms such as vague abdominal pain, weight loss or changes in bowel habits. Tumor behavior cannot be predicted by histological features alone, and malignancy is determined by the presence of metastases. We report here a case of malignant pancreatic endocrine tumor producing somatostatin presented as relapsing cholangitis who was treated with Whipple pancreatoduodenectomy.

Regression of liver metastases of occult carcinoid tumor with slow release Lanreotide therapy

Few clinical studies have demonstrated an anti-proliferative activity of somatostatin (SST) analogs in carcinoids. We report the case of a woman with liver metastases of neuroendocrine tumor and no evidence of the primary tumor. The liver metastases were characterized by high proliferation index, immunoreactiviy for somatostatin receptor (SSTR)-1, 2, 3 and 5 and positive octreoscan. Urinary 5-hydroxyindolacetic acid, serum serotonin and chromogranin A were elevated. Slow release lanreotide (SR-LAN) therapy for 3 mo controlled clinical and biochemical signs of carcinoid tumor and caused a clear-cut reduction in the diameter of two liver metastases and disappearance of another lesion, with further reduction after 6 and 18 mo. We demonstrated a clear-cut long-lasting anti-proliferative effect of SR-LAN on liver metastases of occult carcinoid with high proliferation index and immunoreactivity for SSTR-1, 2, 3, and 5. Immuno-histochemistry for SSTRs could be a suitable method for the selection of patients with metastatic carcinoid that may benefit from SST analog therapy.

The importance of preoperative localisation procedures in organic hyperinsulinism--experience in 67 patients

BACKGROUND

Preoperative localisation of insulinomas has been regarded unnecessary, given the significantly higher detection rates of intraoperative ultrasonography and bidigital palpation. These are mandatory before endoscopic surgery.

METHODS

67 patients operated on for organic hyperinsulinism were retrospectively analysed regarding tumour localisation within the pancreas, tumour size, histological findings, sensitivities of preoperative imaging methods, and surgical techniques.

RESULTS

59 patients (88%) had solitary insulinomas, four patients (6%) multiple insulinomas and four adult patients (6%) nesidioblastosis. Well-differentiated neuroendocrine tumours with benign behaviour (including four patients with nesidioblastosis) were diagnosed in 53 patients (79%), tumours with uncertain behaviour in nine patients (13%) and well-differentiated neuroendocrine carcinomas in five (8%). Tumours were evenly distributed throughout the pancreas. Endoscopic ultrasound localised tumours in 15 out of 21 patients (71%), conventional computed tomography (CT) in 7 out of 21 (33%), single-slice helical CT in 7 out of 12 (58%), multidetector CT in 5 out of 5 (100%), magnetic resonance imaging in 11 out of 13 (85%) and angiography in 15 out of 23 (65%). Various combinations of available methods achieved a sensitivity of 88% (49 patients true positive, 4 true negative, 7 false negative). Of 59 patients, solitary insulinomas were enucleated in 47 (80%), 11 patients underwent conventional open resection and one patient endoscopic distal pancreatic resection. Patients with nesidioblastosis or multiple tumours underwent pancreatic resections alone or in combination with enucleations.

CONCLUSION

After biochemical diagnosis of organic hyperinsulinism, preoperative localisation is necessary for planning endoscopic pancreatic surgery, because of the possibility of multiple insulinomas, malignancy or nesidioblastosis in adults.

Survival and clinical outcome of patients with neuroendocrine tumors of the gastroenteropancreatic tract in a german referral center

Neuroendocrine tumors (NETs) are rare neoplasms. Approximately 75% of all cases manifest in the gastroenteropancreatic (GEP) system. Because of the low incidence of NETs, limited data about the clinical outcome and prognostic variables are available. In an attempt to identify prognostic parameters, we investigated the distribution of primary tumors, pattern of metastasis formation, clinical presentation, histological classification, and outcome of therapeutic interventions in a large patient cohort cared for in a German referral center. In 254 patients with GEP-NETs, the primary tumor was of foregut, midgut, or hindgut origin in 44.1% (28.7% pancreas), 43.7% (34.7% jejunoileum), and 4.3%, respectively. No primary tumor was found in 7.9%. Metastases occurred preferentially in lymph nodes and the liver. The overall 5-year survival rate was 57.1%. In the absence or presence of metastases at initial diagnosis the 5-year survival rate was 80.0% and 51.7%, respectively. The 5-year survival rate was related to the localization of the primary and was 75.0% and 42.9% for jejunoileal and pancreatic tumors, respectively. The size of the primary tumor (<2 cm) and histological grading as low-grade malignant were both associated with a significantly longer survival. Surgery with curative intent was attempted in 141 patients. However, an R(0) resection was achieved in only 66.0% of these patients. Five-year survival rate in the latter group was significantly higher (77.3%) as compared with all surgical patients (55.4%). Long-term tumor-free survival was obtained in only 53.7% of successfully resected patients. Palliative medical treatment, either with chemotherapy (i.e., especially for foregut NETs) or biotherapy (especially for midgut NETs), was only moderately effective for both therapeutic regimens.

Tumour biology of gastroenteropancreatic neuroendocrine tumours

Neuroendocrine tumours of the gastroenteropancreatic tract (GEP NETs) represent a rare and heterogeneous group of tumours. Based on their ontogenetic origin, GEP NETs are classified into foregut, midgut and hindgut tumours. Although they have many features in common, their molecular backgrounds are obviously different. Elucidation of the key factors determining tumour biology has been hampered by the low incidence and high variability of these tumours in terms of origin, morphology and growth. However, recent years have shed some light on molecular genetics of these tumours, revealing important genetic factors as the RET proto-oncogene and the tumour suppressor menin as well as knowledge about the role of growth factors like IGF-1, TGF-beta, VEGF and PDGF for the regulation of differentiation, growth and secretion. In the future, emerging molecular tools in rapid individual genome analysis and in proteomic and array technologies may help to delineate common patterns of NET disease.

Expression of somatostatin receptor subtypes 1 to 5 in tumor tissue and intratumoral vessels in malignant endocrine pancreatic tumors

Somatostatin analogs are well established in the treatment of malignant endocrine pancreatic tumors (EPTs). Our goal is to individualize their treatment using receptor-subtype-specific analogs and, therefore, exploring the receptor expression is highly important. We have examined the expression of somatostatin receptor (sst) subtypes 1-5 on tumor cells and in intratumoral vessels in 28 tumor tissues from malignant EPTs with immunohistochemistry using sst-subtype-specific polyclonal antibodies. We found that sst(2) and sst(4) stained positive in 90% and sst(1) in 70% of the tumor tissues, whereas sst(3) and sst(5) stained positive in only 50% of the tumor tissues. Sst expression in intratumoral vessels was high for sst(2) and sst(4) (80%), moderate for sst(1) (40%), and low for sst(3) and sst(5) (10%). The ssts were evenly distributed among the different tumor subtypes. However, tumors belonging to the same subgroup of EPTs showed a variable expression of receptor subtypes. No differences in receptor-subtype expression could be seen between poorly and welldifferentiated tumors, nor between primary tumors and metastases. Prior medical treatment did not influence sst expression pattern. In conclusion, sst(2) and sst(4) were expressed in most tumor tissues and intratumoral vessels from EPTs. However, sst(3) and sst(5) were lacking in half of the tumor tissues and in most of the intratumoral vessels. These differences indicate the importance of determining each tumor s subset of receptors before treatment with receptor-subtype-specific analogs is initiated. The importance of sst expression in intratumoral vessels is not yet known.

Solitary versus multiple carcinoid tumors of the ileum: a clinical and pathologic review of 68 cases

It is well known that small intestinal carcinoid tumors may occur as solitary or multiple lesions. However, the biologic significance of multiple carcinoid tumors has not been clearly defined. The purpose of this study was to compare the clinical and pathologic features and prognosis of patients with solitary versus multiple carcinoid tumors of the ileum. Sixty-eight patients, including 50 with solitary and 18 with multiple carcinoid tumors, were included in the study. Hematoxylin and eosin-stained slides from routinely processed tumor resection specimens of the ileum were evaluated for a variety of histologic features such as tumor size, depth of invasion, tumor stage, and venous, perineural, and lymphovascular invasion. Follow-up and clinical data, such as patient age, gender, presenting complaints, presence of synchronous or metachronous malignancies, and presence of the carcinoid syndrome, were obtained and the results were compared between the two patient groups. Fifty patients with solitary carcinoid tumors (male/female ratio, 27:23) and 18 patients with multiple tumors (male/female ratio, 7:11) were identified. Patients with multiple carcinoid tumors were significantly younger than patients with solitary tumors at the time of diagnosis (55 years vs 63 years, p = 0.006). There was a high association between multiple carcinoid tumors and the carcinoid syndrome (4 of 18 vs 1 of 50, p = 0.004) as compared with patients with solitary carcinoid tumors. There was also an association between tumor multiplicity and venous invasion, but this relationship was not statistically significant (p = 0.07). The follow-up period was similar for both groups (mean 36 months, median 26 months, range 1-139 months). A significantly higher proportion of patients with multiple carcinoid tumors were either alive with disease or died of disease (56%) compared with those with solitary carcinoid tumors (18%, p = 0.002), and this relationship persisted in multivariate analysis (p = 0.02). Overall, no significant differences were observed between these two patient groups with respect to other clinicopathologic features such as tumor size, depth of invasion, presence of distant metastases, lymphatic or perineural invasion, or presence of an associated malignancy (p >0.05). In conclusion, we found that patients with multiple carcinoid tumors are younger, have a significantly greater risk of developing the carcinoid syndrome, and have a poorer prognosis than patients with solitary tumors.

Prevalence and prognostic significance of acinar cell differentiation in pancreatic endocrine tumors

We have noted that many histologically and immunohistochemically confirmed pancreatic endocrine tumors show immunophenotypic evidence of acinar cell differentiation, but the clinical relevance of this finding is unknown. We performed this study to evaluate the prevalence and prognostic significance of exocrine differentiation by immunohistochemistry in pancreatic endocrine tumors that do not show morphologic features of acinar cell differentiation. Routinely processed tissue sections from 87 pancreatic endocrine tumors were immunohistochemically stained with monoclonal antibodies against acinar (lipase, chymotrypsin, trypsin) and endocrine cell markers (chromogranin A, neuron-specific enolase, synaptophysin, Leu-7) and for the proliferation-associated peptide Ki67. The degree of staining with each marker was graded on a three-tier scale for acinar markers (grade 0, <5%; grade 1, 5-10%; grade 2, 11-25%; and grade 3, >25%) and on a four-tier scale for endocrine markers (grade 0, <5%; grade 1, 5-25%; grade 2, 26-50%; grade 3, 51-75%; and grade 4, >75%), and the results were correlated with clinical outcome (mean follow-up 53 months). Greater than 75% of the tumor cells stained for chromogranin A, neuron-specific enolase, synaptophysin, and Leu-7 in 100%, 96%, 93%, and 27% of cases, respectively. Overall, 66% of tumors stained positively for at least one acinar cell marker, 31% stained for at least two acinar cell markers, and 13% stained for all three acinar cell markers. Forty-seven percent stained for lipase (23 grade 1, 11 grade 2, seven grade 3), 37% for trypsin (22 grade 1, three grade 2, seven grade 3), and 25% stained for chymotrypsin (13 grade 1, five grade 2, four grade 3). No correlation was noted between the presence or extent of expression of any single or combination of acinar cell markers and clinical outcome. However, higher tumor stage correlated with a poor clinical outcome (p = 0.002), and location in the tail of the pancreas was associated with a longer interval to tumor recurrence (p = 0.03). The presence of synaptophysin (p = 0.03) and Leu-7 expression (p = 0.03) correlated significantly with less aggressive clinical behavior. An association was observed between increased Ki67 labeling and poorer clinical outcome, but this was not statistically significant (p >0.05). In conclusion, immunophenotypic evidence of acinar cell differentiation is common in pancreatic endocrine tumors, but this feature does not have any relevance to clinical prognosis. However, in addition to tumor stage, location in the pancreatic tail and the immunohistochemical expression of synaptophysin and/or Leu-7 may be useful prognostic indicators in patients with these lesions.

Standardisation of imaging in neuroendocrine tumours: results of a European delphi process

In 1998 and 1999, a delphi consensus procedure was performed to establish guidelines for standardised diagnostic imaging of neuroendocrine tumours. The procedure included four consecutive workshops of a European group of experts in neuroendocrine tumours as well as feedback given by specialists from the departments of radiology, nuclear medicine, surgery and internal medicine of the according home institutions. Diverging approaches among the centres, which became apparent during the discussion, reflect a lack of controlled studies specifically for rare subgroups of neuroendocrine tumours. This paper summarises the standards for diagnostic imaging as developed during the delphi process. In particular, the diagnostic workflows as well as the technical properties of different imaging modalities are described in detail.

Isolation, maintenance, and characterization of human pancreatic islet tumor cells expressing vasoactive intestinal peptide

Tissue from a vasoactive intestinal peptide (VIP)-secreting human tumor has been used to establish and characterize human neuroendocrine primary cell cultures from which permanent, clone-derived cell lines have been established. Viable cells were obtained by enzymatic and mechanical dissociation of freshly resected pancreatic islet tumor and hepatic metastatic tumor tissues. Aliquots of tumor cells were established ex vivo under culture conditions including porous substrata coated with type IV collagen and laminin and a low serum, hormonally defined culture medium. The small (<10 microm) rounded, grape-like cells had a very slow growth rate of doubling times estimated at several weeks or more. After several passages, morphologically uniform cells were derived that strongly expressed neuroendocrine markers of synaptophysin and synaptobrevin. Although chromogranin A and VIP had somewhat weaker expression, both demonstrated phorbol ester-stimulated secretion. The morphologic and secretory properties were maintained by the cells for nearly 2 years in culture. The establishment of this novel VIP-secreting human neuroendocrine cell line (HuNET) makes available a culture model with which to study a transformed version of this pancreatic islet cell type and offers approaches by which to establish islet tumor cell lines.

Human Insulinomas: Clinical, Cellular, and Molecular Aspects

Insulinoma is the most frequently encountered functioning endocrine pancreatic tumor in humans. In this overview we summarize morphological and clinical features of insulinomas, report about the proinsulin-insulin conversion in normal and neoplastic B-cells, discuss the new classification, the criteria of malignancy, and the clonal composition of endocrine pancreatic tumors, and outline recent findings on the molecular pathology of these tumors.