Influence of somatostatin receptor scintigraphy and CT/MRI on the clinical management of patients with gastrointestinal neuroendocrine tumors: an analysis in 188 patients

Neuroendocrine Neoplasms of the Small Bowel and Pancreas

The traditionally promulgated perspectives of neuroendocrine neoplasms (NEN) as rare, indolent tumours are blunt and have been outdated for the last 2 decades. Clear increments in their incidence over the past decades render them increasingly clinically relevant, and at initial diagnosis many present with nodal and/or distant metastases (notably hepatic). The molecular pathogenesis of these tumours is increasingly yet incompletely understood. Those arising from the small bowel (SB) or pancreas typically occur sporadically; the latter may occur within the context of hereditary tumour predisposition syndromes. NENs can also be associated with endocrinopathy of hormonal hypersecretion. Tangible advances in the development of novel biomarkers, functional imaging modalities and therapy are especially applicable to this sub-set of tumours. The management of SB and pancreatic neuroendocrine tumours (NET) may be challenging, and often comprises a multidisciplinary approach wherein surgical, medical, interventional radiological and radiotherapeutic modalities are implemented. This review provides a comprehensive overview of the epidemiology, pathophysiology, diagnosis and treatment of SB and pancreatic NETs. Moreover, we provide an outlook of the future in these tumour types which will include the development of precision oncology frameworks for individualised therapy, multi-analyte predictive biomarkers, artificial intelligence-derived clinical decision support tools and elucidation of the role of the microbiome in NEN development and clinical behaviour.

Unusual Sites of High-Grade Neuroendocrine Carcinomas: A Case Series and Review of the Literature

Case series

Patient: Female, 29 • Female, 69 • Female, 52 • Female, 71 • Male, 62 • Female, 67

Final Diagnosis: Neuroendocrine carcinoma

Symptoms: Abdominal pain

Medication: —

Clinical Procedure: —

Specialty: Oncology

Functional Imaging in the Follow-Up of Enteropancreatic Neuroendocrine Tumors: Clinical Usefulness and Indications

CONTEXT

Functional imaging tests (FITs) detecting somatostatin receptor expression [i.e., somatostatin receptor scintigraphy, 68Ga-DOTA positron emission tomography/computed tomography (CT)] have a pivotal role in the diagnosis of neuroendocrine tumors (NETs), although their indication during follow-up still needs to be clarified.

OBJECTIVE

Investigate the role of FITs after diagnosis of metastatic enteropancreatic NETs, identifying patients who might benefit from these exams.

DESIGN

Multicenter retrospective analysis of metastatic enteropancreatic NETs.

SETTING

Analysis of imaging tests performed between January 1995 and December 2015 in Rome, Berlin, Milan, Marburg, or Graz.

SUBJECTS

One hundred forty-three patients with metastatic pancreatic NETs and small intestine NETs, at least 2-year follow-up, and positive FITs.

INTERVENTIONS

Patients had received CT every 6 months (unless clinical conditions and tumor behavior required shorter intervals) and FIT every 12 months.

MAIN OUTCOME MEASURES

Clinical usefulness of FITs, defined as changes in patient management (indication to biopsy, medical therapy, surgery, or further imaging tests) due only to FITs.

RESULTS

FITs affected management in 73.4% of patients, mostly when G2 vs G1 [odds ratio (OR), 2.40; 95% confidence interval (CI), 1.09 to 5.27; P = 0.03]. Changes were observed in a 12-month time frame especially with pancreatic NETs vs small intestine NETs (OR, 2.89; 95% CI, 1.09 - 7.67; P = 0.03) or metastases since diagnosis vs developed during follow-up (OR, 4.00; 95% CI, 1.43 to 11.17; P < 0.01).

CONCLUSIONS

FITs used in addition to CT in the follow-up of stage IV enteropancreatic NETs improve patient management (especially for G2 tumors). Follow-up program should be tailored according to tumor features.

The status of neuroendocrine tumor imaging: from darkness to light?

Diagnostic imaging plays a pivotal role in the diagnosis, staging, treatment selection and follow-up for neuroendocrine tumors. The available diagnostic strategies are morphologic imaging, including computed tomography, magnetic resonance imaging (MRI) and ultrasound techniques, and molecular imaging, including scintigraphy with (111)In-pentetreotide and positron emission tomography with (68)Ga-DOTA-peptides, (18)F-DOPA and (11)C-5-HTP. A combination of anatomic and functional techniques is routinely performed to optimize sensitivity and specificity. The introduction of diffusion-weighted MRI and dynamic contrast-enhanced techniques represents a promising advance in radiologic imaging, whereas new receptor-binding peptides, including somatostatin agonists and antagonists, represent the recent most favorable innovation in molecular imaging. Future development includes the short-term validation of these techniques, but in extension also a more comprehensive multilevel integration of biologic information pertaining to a specific tumor and patient, possibly encompassing genomic considerations, currently evolving as a new entity denoted 'precision medicine'. The ideal is a diagnostic sequence that captures the global status of an individual's tumor and encompasses a multidimensional characterization of tumor location, metabolic performance and target identification. To date, advances in imagery have focused on increasing resolution, discrimination and functional characterization. In the future, the fusion of imagery with the parallel analysis of biological and genomic information has the potential to considerably amplify diagnosis.

Advanced small-cell colon carcinoma: a case report

Introduction

Small-cell colon carcinoma is a very rare disease among colon neoplasms; it is difficult to achieve long-term survival due to its aggressive tumor behavior. Here we report the long-term survival of a patient with advanced small-cell colon carcinoma achieved by a combination of surgery and continuous chemotherapy.

Case presentation

A 67-year-old Japanese man underwent abdominal computed tomography in our institution for follow up after gastrectomy, and abnormal thickness of the sigmoid colon wall was revealed. An endoscopy demonstrated a 20mm Bormann 2 lesion with central ulceration located 20cm from the anal verge. A sigmoidectomy was performed. Histologically, the tumor deeply invaded the tissue and extended beyond the serosa, and was diagnosed as small-cell carcinoma. Cisplatin plus irinotecan was administered for adjuvant chemotherapy. Nine months after surgery, a follow-up computed tomography showed an enlarged lymph node behind the inferior vena cava and a 15×8mm nodule located at the ventral side of the cecum. Under consideration of progressive disease, cisplatin plus irinotecan therapy was performed again using the same regimen. After nine cycles of cisplatin plus irinotecan therapy, a follow-up gastric endoscopy demonstrated external tumor invasion to the duodenum wall. Carboplatin plus etoposide therapy was selected as a third-line regimen. After six cycles of carboplatin plus etoposide therapy, the recurrence sites were maintained in a stable condition, and the survival time reached approximately 30 months after the initial surgery.

Conclusions

We report the long-term survival of a patient with advanced small-cell colon carcinoma. In the future, the accumulation and analysis of rare cases that obtain a better survival time will contribute to clarifying neuroendocrine carcinoma biology, and help to improve the prognosis.

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.

SPECT/CT stabilizes the interpretation of somatostatin receptor scintigraphy findings: a retrospective analysis of inter-rater agreement

OBJECTIVE

Correlating the anatomical information from CT with the functional information from SPECT improves diagnostic accuracy of somatostatin-receptor-scintigraphy (SRS) in patients with neuroendocrine tumors (NET). The aim of the present study was to investigate the impact of dual modality SPECT/CT on the inter-rater agreement in SRS.

METHODS

Twenty-five unselected patients with suspected or histologically proven NET in whom whole body planar imaging and low-dose SPECT/CT had been performed after injection of 200 MBq In-111-octreotide were included retrospectively. Images were interpreted independently by 2 nuclear medicine physicians, an experienced one and an inexperienced one. Both readers first re-evaluated the planar whole-body images alone, then added the SPECT images, and finally the CT-images. Lesions with pathologically increased tracer uptake were categorized according to the following 3-point score: equivocal, probably pathologic, and definitely pathologic. Cohen's linear-weighted kappa coefficient kappa was used to quantify inter-rater agreement.

RESULTS

A total number of 50 lesions were described in 23 of the 25 patients. The two readers showed only moderate agreement in the interpretation of the planar findings (kappa = 0.593). Agreement improved to substantial by adding SPECT (kappa = 0.736) and to very good by adding SPECT/CT (kappa = 0.860). SPECT/CT resulted in up-staging of 18% of the lesions and down-staging of 12% compared to planar + SPECT (experienced reader). In addition, SPECT/CT tended to reduce the frequency of indefinite scores (equivocal, probably pathologic), from 18% in planar + SPECT to 6% (p = 0.065). Change of lesion localization by SPECT/CT tended to contribute to the change of lesion score (p = 0.055).

CONCLUSION

The present results suggest that low-dose SPECT/CT stabilizes report quality in SRS by improving inter-rater agreement.

Differential efficacy of SSTR1, -2, and -5 agonists in the inhibition of C6 glioma growth in nude mice

Somatostatin receptors (SSTR1-5) mediate antiproliferative effects. In C6 rat glioma cells, somatostatin is cytostatic in vitro via phosphotyrosine phosphatase-dependent inhibition of ERK1/2 activity mediated by SSTR1, -2, and -5. Here we analyzed the effects of SSTR activation on C6 glioma growth in vivo and the intracellular mechanisms involved, comparing somatostatin effects with selective agonists for SSTR1, -2, and -5 (BIM-23745, BIM-23120, BIM-23206) or receptor biselective compounds (SSTR1 and -2, BIM-23704; and SSTR2 and -5, BIM-23190). Nude mice subcutaneously xenografted with C6 cells were treated with somatostatin, SSTR agonists (50 μg, twice/day), or vehicle. Tumor growth was evaluated every 3 days for 19 days. The intracellular pathways responsible of SSTR effects in vivo were evaluated measuring Ki-67, phospho-ERK1/2, and p27(kip1) expression by immunohistochemistry in sections from explanted tumors. Somatostatin and SSTR1, -2, and -5 agonists strongly inhibited in vivo C6 tumor growth, intratumoral neovessel formation, Ki-67 expression, and ERK1/2 phosphorylation and induced upregulation of p27(Kip1), whereas only a modest activation of caspase-3 was observed. Somatostatin (acting on SSTR1, -2, and -5) displayed the highest efficacy; SSTR5 selective agonist showed a stronger effect than SSTR1 agonist, and SSTR2 agonist was less effective. On the other hand, SSTR1 and -2 agonists maximally reduced tumor neovascularization. The combined activation of SSTR1 and -2 showed a synergistic activity, reaching a higher efficacy than BIM-23206, whereas the simultaneous activation of SSTR2 and -5 resulted in a response resembling SSTR5 effects. Thus the simultaneous activation of different SSTRs inhibits glioma cell proliferation in vivo through both direct cytotostatic and antiangiogenic effects.

Clinical outcome and long-term survival in 118 consecutive patients with neuroendocrine tumours of the pancreas

BACKGROUND

The aim was to assess the clinical relevance of the World Health Organization and tumour node metastasis (TNM) classifications in patients with pancreatic neuroendocrine tumours (pNETs).

METHODS

Prospectively collected data from 118 consecutive patients with a pNET receiving surgical intervention were analysed.

RESULTS

Forty-one patients had well differentiated neuroendocrine tumours, 64 had well differentiated neuroendocrine carcinomas and 13 had poorly differentiated neuroendocrine carcinomas. Five-year survival rates were 95, 44 and 0 per cent respectively (P < 0.001). There was no difference in survival after R0 and R1/R2 resections in patients with neuroendocrine carcinomas (P = 0.905). In those with well differentiated neuroendocrine carcinomas, any resection and having a clinically non-functional tumour significantly increased survival (P = 0.003 and P = 0.037 respectively). The TNM stage was I in 37 patients, II in 15 patients, III in 32 patients and IV in 34 patients. There were significant differences in 5-year survival between stage I and II (88 and 85 per cent respectively) and stage III and IV (31 and 42 per cent respectively) (P = 0.010).

CONCLUSION

Both classifications accurately reflect the clinical outcome of patients with pNET. The resection status may not be critical for long-term survival in patients with pNET.

Gastroenteropancreatic endocrine tumors: clinical characterization before therapy

Gastroenteropancreatic endocrine tumors (GEP ETs) constitute a spectrum of tumors that arise throughout the entire body but are drawn together under a common definition based on the expression of proteins derived from granules, vesicles, or both. GEP ET characterization is dependent on the primary tumor, and encompasses various factors: the WHO classification; hormone-related symptom recognition; hormone marker measurements; screening for inherited syndromes; staging; and somatostatin receptor characterization. Hypervascularization and somatostatin expression constitute major features of endocrine tumors that affect diagnosis, imaging, and therapy. GEP ET prognosis is characterized by its diversity, including a subgroup of patients with slowly progressive disease even at the metastatic stage. Prognosis assessment is mainly based on WHO classification and staging. A second cancer and cardiovascular comorbidity might also play a major prognostic part when present. Mastery of several key points analyzed in this Review, to be applied during the diagnostic and prognostic processes, is essential for defining a tailored therapeutic management.

The clinical impact of a combined gamma camera/CT imaging system on somatostatin receptor imaging of neuroendocrine tumours

AIM

With a combined gamma camera/CT imaging system, CT images are obtained which are inherently registered to the emission images and can be used for the attenuation correction of SPECT and for mapping the functional information from these nuclear medicine tomograms onto anatomy. The aim of this study was to evaluate the clinical impact of SPECT/CT using such a system for somatostatin receptor imaging (SRI) of neuroendocrine tumours.

MATERIALS AND METHODS

SPECT/CT imaging with (111)In-Pentetreotide was performed on 29 consecutive patients, the majority of whom had carcinoid disease. All SPECT images were first reported in isolation and then re-reported with the addition of the CT images for functional anatomical mapping (FAM).

RESULTS

Fifteen of the 29 SPECT images were reported as abnormal, and in 11 of these abnormal images (73%) FAM was found to either establish a previously unknown location (7/11) or change the location (4/11) of at least one lesion. The revised location could be independently confirmed in 64% of these cases. Confirmation of location was not possible in the other patients due to either a lack of other relevant investigations, or the fact that lesions seen in the SPECT images were not apparent in the other investigations. FAM affected patient management in 64% of the cases where the additional anatomical information caused a change in the reported location of lesions.

CONCLUSION

These results imply that FAM can improve the reporting accuracy for SPECT SRI with significant impact on patient management.

Value of image fusion using single photon emission computed tomography with integrated low dose computed tomography in comparison with a retrospective voxel-based method in neuroendocrine tumours

The objective was the evaluation of single photon emission computed tomography (SPECT) with integrated low dose computed tomography (CT) in comparison with a retrospective fusion of SPECT and high-resolution CT and a side-by-side analysis for lesion localisation in patients with neuroendocrine tumours. Twenty-seven patients were examined by multidetector CT. Additionally, as part of somatostatin receptor scintigraphy (SRS), an integrated SPECT-CT was performed. SPECT and CT data were fused using software with a registration algorithm based on normalised mutual information. The reliability of the topographic assignment of lesions in SPECT-CT, retrospective fusion and side-by-side analysis was evaluated by two blinded readers. Two patients were not enrolled in the final analysis because of misregistrations in the retrospective fusion. Eighty-seven foci were included in the analysis. For the anatomical assignment of foci, SPECT-CT and retrospective fusion revealed overall accuracies of 91 and 94% (side-by-side analysis 86%). The correct identification of foci as lymph node manifestations (n=25) was more accurate by retrospective fusion (88%) than from SPECT-CT images (76%) or by side-by-side analysis (60%). Both modalities of image fusion appear to be well suited for the localisation of SRS foci and are superior to side-by-side analysis of non-fused images especially concerning lymph node manifestations.

Clinical endocrinology and metabolism. The somatostatin neuroendocrine system: physiology and clinical relevance in gastrointestinal and pancreatic disorders

Somatostatin is produced in enteroendocrine D cells and intrinsic neurons of the stomach, intestines and pancreas. Its physiologic actions are mediated primarily by somatostatin receptors type 2 and 5, and include the inhibition of secretion of most endocrine and exocrine factors. Diseases directly attributable to somatostatin excess or deficiency are rare, although there is a complex pathogenic relationship between persistent Helicobacter pylori infection and reduced somatostatin in chronic gastritis. Abundant somatostatin receptors on many neoplastic and inflammatory cells are the basis for sensitive in vivo imaging with radiolabeled somatostatin analogs and provide a therapeutic target. Current indications for somatostatin therapy include hormone-expressing neuroendocrine tumors, intractable diarrhea and variceal bleeding secondary to portal hypertension. Exciting advances are being made in the development of high-affinity nonpeptide analogs with receptor-subtype selectivity and increased bioavailability. Somatostatin analogs coupled to high-energy radionuclides show promise as novel cytotoxic agents for certain metastatic tumors.