(131)I-MIBG radionuclide therapy is safe and cost-effective in the control of symptoms of the carcinoid syndrome

High-specific-activity iodine 131 metaiodobenzylguanidine for the treatment of metastatic pheochromocytoma or paraganglioma: a novel therapy for an orphan disease

PURPOSE OF REVIEW

Pheochromocytomas and paragangliomas represent less than 1% of all endocrine tumors. Approximately 15-20% of these tumors are malignant. The definition of malignancy relies on the presence of metastasis. Metastatic pheochromocytomas and paragangliomas are usually advanced, incurable tumors with limited therapeutic options. About 50-60% of these tumors express the noradrenaline transporter in their cell membranes. Recently, the United States Food and Drug Administration approved high-specific-activity iodine 131 metaiodobenzylguanidine (HSA-I-131-MIBG) for the treatment of metastatic pheochromocytomas and paragangliomas that express the noradrenaline transporter. This review reports the benefits and toxicity of HSA-I-131-MIBG, its physical and dosimetric aspects, and radiation safety precautions, as well as its potential therapeutic value for other malignancies (neuroblastoma, gastroenteropancreatic neuroendocrine tumors, and medullary thyroid carcinoma).

RECENT FINDINGS

A phase 2 clinical trial with HSA-I-131-MIBG reported an impressive clinical benefit rate, acceptable toxicity and long-term benefits.

SUMMARY

HSA-I-131-MIBG is an effective medication for metastatic pheochromocytomas and paragangliomas that express the noradrenaline transporter.

Carcinoid syndrome: update on the pathophysiology and treatment

Approximately 30-40% of patients with well-differentiated neuroendocrine tumors present with carcinoid syndrome, which is a paraneoplastic syndrome associated with the secretion of several humoral factors. Carcinoid syndrome significantly and negatively affects patients' quality of life; increases costs compared with the costs of nonfunctioning neuroendocrine tumors; and results in changes in patients' lifestyle, such as diet, work, physical activity and social life. For several decades, patients with neuroendocrine tumors and carcinoid syndrome have been treated with somatostatin analogues as the first-line treatment. While these agents provide significant relief from carcinoid syndrome symptoms, there is inevitable clinical progression, and new therapeutic interventions are needed. More than 40 substances have been identified as being potentially related to carcinoid syndrome; however, their individual contributions in triggering different carcinoid symptoms or complications, such as carcinoid heart disease, remain unclear. These substances include serotonin (5-HT), which appears to be the primary marker associated with the syndrome, as well as histamine, kallikrein, prostaglandins, and tachykinins. Given the complexity involving the origin, diagnosis and management of patients with carcinoid syndrome, we have undertaken a comprehensive review to update information about the pathophysiology, diagnostic tools and treatment sequence of this syndrome, which currently comprises a multidisciplinary approach.

Predictors of Survival in 211 Patients with Stage IV Pulmonary and Gastroenteropancreatic MIBG-Positive Neuroendocrine Tumors Treated with 131I-MIBG

This retrospective analysis identifies predictors of survival in a cohort of patients with meta-iodobenzylguanidine (MIBG)-positive stage IV pulmonary and gastroenteropancreatic neuroendocrine tumor (P/GEP-NET) treated with ¹³¹I-MIBG therapy, to inform treatment selection and posttreatment monitoring. Methods: Survival, symptoms, imaging, and biochemical response were extracted via chart review from 211 P/GEP-NET patients treated with ¹³¹I-MIBG between 1991 and 2014. For patients with CT follow-up (n = 125), imaging response was assessed by RECIST 1.1 if images were available (n = 76) or by chart review of the radiology report if images could not be reviewed (n = 49). Kaplan-Meier analysis and Cox multivariate regression estimated survival and progression-free survival benefits predicted by initial imaging, biochemical response, and symptomatic response. Results: All patients had stage IV disease at the time of treatment. Median survival was 29 mo from the time of treatment. Symptomatic response was seen in 71% of patients, with the median duration of symptomatic relief being 12 mo. Symptomatic response at the first follow-up predicted a survival benefit of 30 mo (P < 0.001). Biochemical response at the first clinical follow-up was seen in 34% of patients, with stability of laboratory values in 48%; response/stability versus progression extended survival by 40 mo (P < 0.03). Imaging response (20% of patients) or stability (60%) at the initial 3-mo follow-up imaging extended survival by 32 mo (P < 0.001). Additionally, multiple ¹³¹I-MIBG treatments were associated with 24 mo of additional survival (P < 0.05). Conclusion: Therapeutic ¹³¹I-MIBG for metastatic P/GEP-NETs appears to be an effective means of symptom palliation. Imaging, biochemical, and symptomatic follow-up help prognosticate expected survival after ¹³¹I-MIBG therapy. Multiple rounds of ¹³¹I-MIBG are associated with prolonged survival.

Carcinoid-syndrome: recent advances, current status and controversies

PURPOSE OF REVIEW

To review recent advances and controversies in all aspects of carcinoid-syndrome.

RECENT FINDINGS

Over the last few years there have been a number of advances in all aspects of carcinoid syndrome as well as new therapies. These include new studies on its epidemiology which demonstrate it is increasing in frequency; increasing insights into the pathogenesis of its various clinical manifestations and into its natural history: definition of prognostic factors; new methods to verify its presence; the development of new drugs to treat its various manifestations, both initially and in somatostatin-refractory cases; and an increased understanding of the pathogenesis, natural history and management of carcinoid heart disease. These advances have generated several controversies and these are also reviewed.

SUMMARY

There have been numerous advances in all aspects of the carcinoid-syndrome, which is the most common functional syndrome neuroendocrine tumors produce. These advances are leading to new approaches to the management of these patients and in some cases to new controversies.

Norepinephrine Transporter as a Target for Imaging and Therapy

The norepinephrine transporter (NET) is essential for norepinephrine uptake at the synaptic terminals and adrenal chromaffin cells. In neuroendocrine tumors, NET can be targeted for imaging as well as therapy. One of the most widely used theranostic agents targeting NET is metaiodobenzylguanidine (MIBG), a guanethidine analog of norepinephrine. ¹²³I/¹³¹I-MIBG theranostics have been applied in the clinical evaluation and management of neuroendocrine tumors, especially in neuroblastoma, paraganglioma, and pheochromocytoma. ¹²³I-MIBG imaging is a mainstay in the evaluation of neuroblastoma, and ¹³¹I-MIBG has been used for the treatment of relapsed high-risk neuroblastoma for several years, however, the outcome remains suboptimal. ¹³¹I-MIBG has essentially been only palliative in paraganglioma/pheochromocytoma patients. Various techniques of improving therapeutic outcomes, such as dosimetric estimations, high-dose therapies, multiple fractionated administration and combination therapy with radiation sensitizers, chemotherapy, and other radionuclide therapies, are being evaluated. PET tracers targeting NET appear promising and may be more convenient options for the imaging and assessment after treatment. Here, we present an overview of NET as a target for theranostics; review its current role in some neuroendocrine tumors, such as neuroblastoma, paraganglioma/pheochromocytoma, and carcinoids; and discuss approaches to improving targeting and theranostic outcomes.

Refractory carcinoid syndrome: a review of treatment options

Carcinoid syndrome (CSy) is a constellation of symptoms that may commonly present in patients with well differentiated neuroendocrine tumors (NETs), with somatostatin analogs (SSAs) being the first-line option for symptom management. However, symptomatic progression eventually occurs and in this scenario of a refractory CSy; several treatment options have been studied such as dose escalation of SSA, interferon and liver-directed therapies. Nevertheless, recent phase III trials have contributed to the understanding and management of this condition. We performed a comprehensive review of interventional studies examining refractory CSy to provide the evidence for current treatment options and propose a treatment sequence.

I-131 Metaiodobenzylguanidine Therapy of Pheochromocytoma and Paraganglioma

Pheochromocytomas and paragangliomas are rare tumors arising from chromaffin cells. Available therapeutic modalities consist of chemotherapy, tyrosine kinase inhibitors, and I-131 metaiodobenzylguanidine (MIBG). I-131 MIBG is taken up via specific receptors and localizes into many but not all pheochromocytomas and paragangliomas. Because these tumors are rare, most therapy studies are retrospective presentations of clinical experience. Numerous retrospective studies and a few prospective studies have shown favorable responses in this disease, including symptomatic, biochemical, and objective responses. In this report, we review the experience of using I-131 MIBG therapy for targeting pheochromocytoma and paragangliomas.

Treatment of symptomatic neuroendocrine tumor syndromes: recent advances and controversies

Neuroendocrine tumors(NETs), once thought rare, are increasing in frequency in most countries and receiving increasing-attention. NETs present two-treatment problems. A proportion is aggressive and a proportion has a functional, hormone-excess-state(F-NET), each of which must be treated. Recently, there have been many advances, well-covered in reviews/consensus papers on imaging-NETs; new, novel anti-tumor treatments and understanding their pathogenesis. However, little attention has been paid to advances in the treatment of the hormone-excess-state. These advances are usually reported in case-series, and case-reports with few large studies. In this paper these advances are reviewed. Areas covered: Advances in the last 5-years are concentrated on, but a review of literature from the last 10-years was performed. PubMed and other databases (Cochrane, etc.) were searched for F-NET-syndromes including carcinoid-syndrome, as well as meeting-abstracts on NETs. All advances that controlled hormone-excess-states or facilitated-control were covered. These include new medical-therapies [serotonin-synthesis inhibitors(telotristat), Pasireotide, new agents for treating ACTHomas], increased dosing with conventional therapies (octreotide-LAR, Lanreotide-Autogel), mTor inhibitors(everolimus), Tyrosine-kinase inhibitors(sunitinib),cytoreductive surgery, liver-directed therapies (embolization, chemoembolization, radioembolization, RFA), peptide radio-receptor-therapy(PRRT) and 131I-MIBG, ablation of primary F-NETs. Expert opinion: Although many of the newer therapies controlling the hormone-excess-states in F-NETs are reported in relatively few patients, all the approaches show promise. Their description also generates some controversies/unresolved areas,such as the order of these new treatments, their longterm-efficacy, and effectiveness of combinations which may require large,controlled studies.

Neuroendocrine Tumors

Neuroendocrine tumors are increasingly diagnosed, either incidentally as part of screening processes, or for symptoms, which have commonly been mistaken for other disorders initially. The diagnostic workup to characterize tumor behaviour and prognosis focuses on histologic, anatomic, and functional imaging assessments. Several therapeutic options exist for patients ranging from curative and debulking surgery through to liver-directed therapies and systemic treatments. Multimodal therapies are often required over the patient's disease history. The management paradigm can be complex but should be focused on curative resections and then on controlling symptoms and limiting disease progression. There are several new systemic therapies that have completed phase 3 studies with new compounds being studied in phase 2. Genetic and epigenetic markers may lead to a new era of personalised therapy in the future.

Endocrine scintigraphy with hybrid SPECT/CT

Nuclear medicine imaging of endocrine disorders takes advantage of unique cellular properties of endocrine organs and tissues that can be depicted by targeted radiopharmaceuticals. Detailed functional maps of biodistributions of radiopharmaceutical uptake can be displayed in three-dimensional tomographic formats, using single photon emission computed tomography (CT) that can now be directly combined with simultaneously acquired cross-sectional anatomic maps derived from CT. The integration of function depicted by scintigraphy and anatomy with CT has synergistically improved the efficacy of nuclear medicine imaging across a broad spectrum of clinical applications, which include some of the oldest imaging studies of endocrine dysfunction.

Classification, clinicopathologic features and treatment of gastric neuroendocrine tumors

Gastric neuroendocrine tumors (GNETs) are rare lesions characterized by hypergastrinemia that arise from enterochromaffin-like cells of the stomach. GNETs consist of a heterogeneous group of neoplasms comprising tumor types of varying pathogenesis, histomorphologic characteristics, and biological behavior. A classification system has been proposed that distinguishes four types of GNETs; the clinicopathological features of the tumor, its prognosis, and the patient’s survival strictly depend on this classification. Thus, correct management of patients with GNETs can only be proposed when the tumor has been classified by an accurate pathological and clinical evaluation of the patient. Recently developed cancer therapies such as inhibition of angiogenesis or molecular targeting of growth factor receptors have been used to treat GNETs, but the only definitive therapy is the complete resection of the tumor. Here we review the literature on GNETs, and summarize the classification, clinicopathological features (especially prognosis), clinical presentations and current practice of management of GNETs. We also present the latest findings on new gene markers for GNETs, and discuss the effective drugs developed for the diagnosis, prognosis and treatment of GNETs.

Long-term outcome and toxicity after dose-intensified treatment with 131I-MIBG for advanced metastatic carcinoid tumors

Reported experience with systemic (131)I-metaiodobenzylguanidine ((131)I-MIBG) therapy of neuroendocrine tumors comprises different dosing schemes. The aim of this study was to assess the long-term outcome and toxicity of treatment with 11.1 GBq (300 mCi) of (131)I-MIBG per cycle.

METHODS

We performed a retrospective review of 31 patients with advanced metastatic neuroendocrine tumors (20 with carcinoid tumors and 11 with other tumors) treated with (131)I-MIBG. Treatment outcome was analyzed for patients with carcinoid tumors (the most common tumors in this study), and toxicity was analyzed for the entire patient cohort (n = 31). Treatment comprised 11.1 GBq (300 mCi) per course and minimum intervals of 3 mo. The radiographic response was classified according to modified Response Evaluation Criteria in Solid Tumors. Toxicity was determined according to Common Terminology Criteria for Adverse Events (version 3.0) for all laboratory data at regular follow-up visits and during outpatient care, including complete blood counts and hepatic and renal function tests. Survival analysis was performed with the Kaplan-Meier curve method (log rank test; P < 0.05).

RESULTS

The radiographic responses in patients with carcinoid tumors comprised a minor response in 2 patients (10%), stable disease in 16 patients (80%; median time to progression, 34 mo), and progressive disease in 2 patients (10%). The symptomatic responses in patients with functioning carcinoid tumors comprised complete resolution in 3 of the 11 evaluable symptomatic patients (27%), partial resolution in 6 patients (55%), and no significant change in 11 patients. The median overall survival in patients with carcinoid tumors was 47 mo (95% confidence interval, 32-62), and the median progression-free survival was 34 mo (95% confidence interval, 13-55). Relevant treatment toxicities were confined to transient myelosuppression of grade 3 or 4 in 15.3% (leukopenia) and 7.6% (thrombocytopenia) of applied cycles and a suspected late adverse event (3% of patients), myelodysplastic syndrome, after a cumulative administered activity of 66.6 GBq. The most frequent nonhematologic side effect was mild nausea (grade 1 or 2), which was observed in 28% of administered cycles. No hepatic or renal toxicities were noted.

CONCLUSION

Dose-intensified treatment with (131)I-MIBG at a fixed dose of 11.1 GBq (300 mCi) per cycle is safe and offers effective palliation of symptoms and disease stabilization in patients with advanced carcinoid tumors. The favorable survival and limited toxicity suggest that high cycle activities are suitable and that this modality may be used for targeted carcinoid treatment--either as an alternative or as an adjunct to other existing therapeutic options.

Theranostics: evolution of the radiopharmaceutical meta-iodobenzylguanidine in endocrine tumors

Since 1981, meta-iodobenzylguanidine (MIBG), labeled with (131)I and later (123)I, has become a valuable agent in the diagnosis and therapy of a number of endocrine tumors. Initially, the agent located pheochromocytomas and paragangliomas (PGLs), both sporadic and familial, in multiple anatomic sites; surgeons were thereby guided to excisional therapies, which were previously difficult and sometimes impossible. The specificity in diagnosis has remained above 95%, but sensitivity has varied with the nature of the tumor: close to 90% for intra-adrenal pheochromocytomas but 70% or less for PGLs. For patients with neuroblastoma, carcinoid tumors, and medullary thyroid carcinoma, imaging with radiolabeled MIBG portrays important diagnostic evidence, but for these neoplasms, use has been primarily as an adjunct to therapy. Although diagnosis by radiolabeled MIBG has been supplemented and sometimes surpassed by newer scintigraphic agents, searches by this radiopharmaceutical remain indispensable for optimal care of some patients. The radiation imparted by concentrations of (131)I-MIBG in malignant pheochromocytomas, PGLs, carcinoid tumors, and medullary thyroid carcinoma has reduced tumor volumes and lessened excretions of symptom-inflicting hormones, but its value as a therapeutic agent is being fulfilled primarily in attacks on neuroblastomas, which are scourges of children. Much promise has been found in tumor disappearance and prolonged survival of treated patients. The experiences with therapeutic (131)I-MIBG have led to development of new tactics and strategies and to well-founded hopes for elimination of cancers. Radiolabeled MIBG is an exemplar of theranostics and remains a worthy agent for both diagnosis and therapy of endocrine tumors.

Carcinoid syndrome and perioperative anesthetic considerations

Carcinoid tumors are uncommon, slow-growing neoplasms. These tumors are capable of secreting numerous bioactive substances, which results in significant potential challenges in the management of patients afflicted with carcinoid syndrome. Over the past two decades, both surgical and medical therapeutic options have broadened, resulting in improved outcomes. The pathophysiology, clinical signs and symptoms, diagnosis, treatment options, and perioperative management, including anesthetic considerations, of carcinoid syndrome are presented.

Therapeutic management of patients with gastroenteropancreatic neuroendocrine tumours

Patients with neuroendocrine tumours (NETs) are best managed in a specialist centre as part of a multidisciplinary team comprising gastroenterologists, oncologists, endocrinologists, gastrointestinal and hepatopancreaticobiliary surgeons, pathologists, nuclear medicine physicians and technicians, radiologists, specialist nurses, pharmacists, biochemists and dieticians. This should ideally be led by a clinician with experience and interest in NETs. Although the number of medical treatments and clinical trials has increased in the decade, there is still a lack of prospective randomised trials; thus, management is mainly based on limited often single-centre studies, although there are now formal guidelines based on consensus expert opinion. We have outlined the current optimal management of patients with NETs. We have reviewed therapeutic options including surgery, somatostatin analogues and other biotherapies and peptide receptor-targeted therapy. We have discussed the challenge in managing hepatic metastases including hepatic artery embolisation, ablation and orthotopic liver transplant. In addition, we have briefly reviewed the emerging therapies such as the mammalian target of rapamycin and angiogenic inhibitors and the newer somatostatin analogues.

Nuclear medicine techniques for the imaging and treatment of neuroendocrine tumours

Nuclear medicine plays a pivotal role in the imaging and treatment of neuroendocrine tumours (NETs). Somatostatin receptor scintigraphy (SRS) with [(111)In-DTPA(0)]octreotide has proven its role in the diagnosis and staging of gastroenteropancreatic NETs (GEP-NETs). New techniques in somatostatin receptor imaging include the use of different radiolabelled somatostatin analogues with higher affinity and different affinity profiles to the somatostatin receptor subtypes. Most of these analogues can also be labelled with positron-emitting radionuclides that are being used in positron emission tomography imaging. The latter imaging modality, especially in the combination with computed tomography, is of interest because of encouraging results in terms of improved imaging quality and detection capabilities. Considerable advances have been made in the imaging of NETs, but to find the ideal imaging method with increased sensitivity and better topographic localisation of the primary and metastatic disease remains the ultimate goal of research. This review provides an overview of the currently used imaging modalities and ongoing developments in the imaging of NETs, with the emphasis on nuclear medicine and puts them in perspective of clinical practice. The advantage of SRS over other imaging modalities in GEP-NETs is that it can be used to select patients with sufficient uptake for treatment with radiolabelled somatostatin analogues. Peptide receptor radionuclide therapy (PRRT) is a promising new tool in the management of patients with inoperable or metastasised NETs as it can induce symptomatic improvement with all Indium-111, Yttrium-90 or Lutetium-177-labelled somatostatin analogues. The results that were obtained with [(90)Y-DOTA(0),Tyr(3)]octreotide and [(177)Lu-DOTA(0),Tyr(3)]octreotate are even more encouraging in terms of objective tumour responses with tumour regression and documented prolonged time to progression. In the largest group of patients receiving PRRT, treated with [(177)Lu-DOTA(0),Tyr(3)]octreotate, a survival benefit of several years compared with historical controls has been reported.

The management of neuroendocrine tumours: current and future medical therapy options

Neuroendocrine tumours (NETs) are a genetically diverse group of malignancies that sometimes produce peptides causing characteristic hormonal syndromes. NETs can be clinically symptomatic (functioning) or silent (non-functioning); both types frequently synthesise more than one peptide, although often these are not associated with specific syndromes. Based on data from various sources, the incidence and prevalence of NETs is increasing. The primary treatment goal for patients with NETs is curative, with symptom control and the limitation of tumour progression as secondary goals. Surgery is the only possible curative approach and so represents the traditional first-line therapy. However, as most patients with NETs are diagnosed once metastases have occurred, curative surgery is generally not possible. Patients therefore require chronic postoperative medical management with the aim of relieving symptoms and, in recent years, suppressing tumour growth and spread. Somatostatin analogues, such as octreotide long-acting repeatable (LAR), can improve the symptoms of carcinoid syndrome and stabilise tumour growth in many patients. Results from the PROMID study show that octreotide LAR 30mg is an effective antiproliferative treatment in patients with newly diagnosed, functionally active or inactive, well-differentiated metastatic midgut NETs. An antiproliferative effect can also be achieved with everolimus, and combination therapy with octreotide LAR has shown synergistic antiproliferative activity. In the future, pasireotide, the multi-receptor targeted somatostatin analogue, has the potential to be an effective therapy for de novo or octreotide-refractory carcinoid syndrome and for inhibiting tumour cell proliferation. Peptide receptor radiotherapy with [90]yttrium-DOTATOC or [177]lutetium-DOTATE is also a new interesting treatment option for NETs.

Direct in vivo injection of 131I-GMS and its distribution and excretion in rabbit

AIM: To explore the distribution and metabolism of ¹³¹I-gelatin microspheres (¹³¹I-GMSs) in rabbits after direct injection into rabbits’ livers.

METHODS: Twenty-eight healthy New Zealand rabbits were divided into seven groups, with four rabbits per group. Each rabbit’s hepatic lobes were directly injected with 41.336 ± 5.106 MBq ¹³¹I-GMSs. Each day after ¹³¹I-GMSs administration, 4 rabbits were randomly selected, and 250 μL of serum was collected for γ count. Hepatic and thyroid functions were tested on days 1, 4, 8, 16, 24, 32, 48 and 64 after ¹³¹I-GMSs administration. Single-photon emission computed tomography (SPECT) was taken for each group on days 0, 1, 4, 8, 16, 24, 32, 48, 64 after ¹³¹I-GMSs administration. A group of rabbits were sacrificed respectively on days 1, 4, 16, 24, 32, 48, 64 after ¹³¹I-GMSs administration. Their livers were taken out for histological examination.

RESULTS: After ¹³¹I-GMSs administration, the nuclide was collected in the hepatic area with microspheres. The radiation could be detected on day 48 after ¹³¹I-GMSs administration, and radiography could be seen in thyroid areas in SPECT on days 4, 8, 16 and 24. One day after ¹³¹I-GMSs administration, the liver function was damaged but recovered 4 d later. Eight days after ¹³¹I-GMSs administration, the levels of free triiodothyronine and free thyroxin were reduced, which restored to normal levels on day 16. Histological examination showed that the microspheres were degraded to different degrees at 24, 32 and 48 d after ¹³¹I-GMSs administration. The surrounding parts of injection points were in fibrous sheathing. No microspheres were detected in histological examination on day 64 after ¹³¹I-GMSs administration.

CONCLUSION: Direct in vivo injection of ¹³¹I-GMSs is safe in rabbits. It may be a promising method for treatment of malignant tumors.

Tumors of the Pancreatic Body and Tail

Tumors of the pancreatic body and tail are uncommon. They have a propensity to present late and often attain a large size with local invasion before they produce any clinical symptoms. The current review aims at comprehensively analysing these tumors with respect to their pathology, presentation, the investigation of these tumors, and finally the latest trends in their surgical and medical management.

Review article: future therapies for management of metastatic gastroenteropancreatic neuroendocrine tumours

BACKGROUND

Gastroenteropancreatic neuroendocrine tumours (GEP NETs) are relatively uncommon tumours that occur anywhere within the gastrointestinal tract. The prevalence of GEP NETs is estimated to be 35 per 100 000 population. Patients often present with metastatic disease and consequently, palliative treatments form the mainstay of therapy.

AIM

To review the current and novel therapeutic options for management of GEP NETs.

METHODS

Searches for all studies related to GEP NETs, NETs and carcinoid tumours in Medline and abstracts from international meetings.

RESULTS

Somatostatin analogues remain the first line therapy for management of symptoms of GEP NETs and may have anti-proliferative action. New somatostatin analogues with different somatostatin receptor affinity have been developed. Radionuclide peptide receptor therapy is established in patients with positive somatostatin scintigraphy. A number of new agents and targeted therapies are currently being evaluated in a phase I and II studies and these include angiogenic inhibitors, mammalian target of rapamycin inhibitors and immune therapies.

CONCLUSIONS

A number of nonsurgical therapies are available for management of gastroenteropancreatic neuroendocrine tumours. It is hoped, the development of some of these promising novel therapies will expand the therapeutic armamentarium.

Assessment of the efficacy and toxicity of (131)I-metaiodobenzylguanidine therapy for metastatic neuroendocrine tumours

(131)I-metaiodobenzylguanidine ((131)I-MIBG) is a licensed palliative treatment for patients with metastatic neuroendocrine tumours. We have retrospectively assessed the consequences of (131)I-MIBG therapy in 48 patients (30 gastroenteropancreatic, 6 pulmonary, 12 unknown primary site) with metastatic neuroendocrine tumours attending Royal Liverpool University Hospital between 1996 and 2006. Mean age at diagnosis was 57.6 years (range 34-81). (131)I-MIBG was administered on 88 occasions (mean 1.8 treatments, range 1-4). Twenty-nine patients had biochemical markers measured before and after (131)I-MIBG, of whom 11 (36.7%) showed >50% reduction in levels post-therapy. Forty patients had radiological investigations performed after (131)I-MIBG, of whom 11(27.5%) showed reduction in tumour size post-therapy. Twenty-seven (56.3%) patients reported improved symptoms after (131)I-MIBG therapy. Kaplan-Meier analysis showed significantly increased survival (P=0.01) from the date of first (131)I-MIBG in patients who reported symptomatic benefit from therapy. Patients with biochemical and radiological responses did not show any statistically significant alteration in survival compared to non-responders. Eleven (22.9%) patients required hospitalisation as a consequence of complications, mostly due to mild bone marrow suppression. (131)I-MIBG therefore improved symptoms in more than half of the patients with metastatic neuroendocrine tumours and survival was increased in those patients who reported a symptomatic response to therapy.

Detecting pheochromocytoma: defining the most sensitive test

OBJECTIVE

To define the most sensitive biochemical test to establish the diagnosis of pheochromocytoma and also to assess the potential role of iodine 131-labeled metaiodobenzylguanidine scintigraphy (I-MIBG) in the diagnosis of this tumor.

SUMMARY BACKGROUND DATA

Pheochromocytoma is a rare, catecholamine-producing tumor with preferential localization in the adrenal gland. Despite its importance, the most sensitive test to establish the diagnosis remains to be defined.

METHODS

Prospective data collection was done on patients with pheochromocytoma treated at the Duke University Medical Center and the Durham Veterans Affairs Medical Center, Durham, NC. All urinary, plasma, and platelet analyses were highly standardized and supervised by one investigator (J.M.F.). I-MIBG scans were independently reviewed by 2 nuclear medicine physicians.

RESULTS

A total of 152 patients (55.3% female) were enrolled in the present analysis. Patients were predominantly white (73.7%). Spells (defined as profuse sweating, tachycardia, and headache) and hypertension at diagnosis were present in 51.4% and 66.6%, respectively. Bilateral disease was found in 12.5%, malignant pheochromocytoma in 29.6%, and hereditary forms in 23.0%. The most sensitive tests were total urinary normetanephrine (96.9%), platelet norepinephrine (93.8%), and I-MIBG scintigraphy (83.7%). In combination with I-MIBG scintigraphy, platelet norepinephrine had a sensitivity of 100%, plasma norepinephrine/MIBG of 97.1%, total urine normetanephrine/MIBG of 96.6%, and urine norepinephrine/MIBG of 95.3%.

CONCLUSIONS

The tests of choice to establish the diagnosis of pheochromocytoma are urinary normetanephrine and platelet norepinephrine. A combination of I-MIBG scintigraphy and diagnostic tests in urine, blood, or platelets does further improve the sensitivity. We thus advocate performing an MIBG scan if the diagnosis of pheochromocytoma is clinically suspected and catecholamine measurements are within the normal range.

Development of a disease-specific Quality of Life questionnaire module for patients with gastrointestinal neuroendocrine tumours

Quality of life (QoL) measurements are increasingly being used as an end point in cancer clinical trials. Standard generic QoL questionnaires may not assess symptoms produced by neuroendocrine tumours. Here we report the development of a disease-specific quality of life score questionnaire for patients with neuroendocrine tumours of the gut to supplement the EORTC core cancer questionnaire, the QLQ-C30. Phases 1-3 of the EORTC quality of life group guidelines for module development were used to design the new questionnaire. Forty-one relevant issues (questions) were generated after an extensive literature search. Following interviews of 15 health care workers and 35 patients, a 35 question provisional questionnaire was constructed. This was translated into seven European languages and pre-tested in 180 patients resulting in a 21-item module that will be validated in an international clinical trial. The EORTC QLQ-NET21 provides a site-specific module to supplement the QLQ-C30 for patients with neuroendocrine tumours.

Long-term efficacy of low activity meta-[131I]iodobenzylguanidine therapy in patients with disseminated neuroendocrine tumours depends on initial response

BACKGROUND

meta-[131I]Iodobenzylguanidine (131I-MIBG) has been used to treat patients with disseminated neuroendocrine tumours (NET). However, so far there is limited information related to the efficacy of this agent beyond the normal 6-month assessment period. Before we can assume that such treatment would be beneficial to patients with these tumours the outcome of the patients over a longer time course should be determined. In many centres financial or radiation protection constraints mean that lower activities of 131I-MIBG have to be used at each administration, therefore instead of giving a single administration of a higher activity 131I-MIBG a series of multiple lower activity administrations are used.

METHODS

The case records of 25 patients who had received 131I-MIBG over a 4-year period, from 1 June 1997 to 30 June 2001, were reviewed. Overall time of clinical follow-up range from 1 to 60 months, with a mean of 16 months). There were 16 female and nine male patients (mean age 55.6 years; range, 30-79 years). Most of patients had carcinoid (17), two had phaeochromocytoma, two gastrinoma and two an undifferentiated NET, one had malignant paraganglioma and one had medullary cell carcinoma of the thyroid. All had avid uptake for 123I-MIBG on diagnostic scanning. The minimum number of treatments received was 1 in 4 patients (with activities of 2.0 to 3.4 GBq); the maximum was 11 treatments (with cumulative activities as high as 29.1 GBq). Treatment was given using an infusion pump and was normally repeated at 12- to 16-week intervals (mean number of treatments per patient, 4). Response to therapy was determined by changes in the size of the tumour on computed tomography and/or magnetic resonance imaging using the response evaluation criteria in solid tumours (RECIST). Toxicity was measured using blood and urine tests of renal, hepatic, thyroid and bone marrow function. The median time from the last treatment to progression of disease and death (if applicable) was also calculated.

RESULTS

No significant or long-lasting toxicity was encountered. At 6 months after the patient's last treatment, 18 patients (72%) had no evidence for progression. Twelve months after their last treatment 12 (48%) patients had no evidence for progression. At 18 months after the patient's last treatment, only seven patients (28%) had no progression of their disease. Overall, the median progression-free survival was 15 months. In those patients with stability or response at 6 months there was a prolonged progression-free survival and overall survival. In those with progression of disease at 6 months, at the 6-month assessment point, there had been four deaths (16%), at 12 months, there were three additional cancer deaths and finally at 18 months, there were a further five deaths. The median survival was 18 months. In those patients who died the mean time interval between disease progression and death was 4.6 months (range 0-12 months).

CONCLUSION

Of the patients treated with low-activity 131I-MIBG 68% had significant benefit for at least 6 months post-treatment. In these patients with progressive and extensive disease this technique provided prolonged progression-free and overall survival with minimal side effects especially if an initial response to treatment was seen.

The palliative role of 131I-MIBG and 111In-octreotide therapy in patients with metastatic progressive neuroendocrine neoplasms

BACKGROUND

Radiolabeled octreotide and metaiodobenzylguanidine (MIBG) have demonstrated limited antitumor effect on neuroendocrine neoplasms (NENs). The purpose of this study was to assess the palliative benefit of radionuclide therapy (RNT) in NENs.

METHODS

Since April 2001, RNT for progressive, nonsurgically resectable NENs was utilized. NENs that were MIBG positive received 131 I-MIBG therapy, whereas octreotide-only-positive neoplasms received 111 In-octreotide therapy. Symptomatic, quality of life (QoL), biochemical, and radiographic responses to RNT were evaluated.

RESULTS

Twenty-four patients had either MIBG or octreotide avid NENs. A mean (range) of 4 (1-7) 131 I-MIBG treatments were given to 13 patients over a duration of 18 months (6-42). The group consisted of 2 medullary thyroid cancer (MTC), and 2 foregut and 9 small-bowel carcinoids; 12 patients (92%) had symptomatic improvement. Stability of tumor size was confirmed in 6, regression in 2, and progression in 5. Biochemical responses were demonstrated in 2. Five (2-16) treatments of 111 In-octreotide was given to 11 patients over 17 months (6-40). There were 1 MTC, 1 insulinoma, 2 gastrinomas, and 3 small-bowel and 4 foregut carcinoids. Symptomatic benefit was seen in 6 (55%), biochemical response in 3. Tumor regression was seen in 1, stability in 5, and progression in 5.

CONCLUSIONS

Radionuclide therapy appears to offer good palliation to patients with progressive NENs.

131I-meta-iodobenzylguanidine in the management of metastatic midgut carcinoid tumors

The management of metastatic neuroendocrine tumors incorporates multimodal therapy with surgery, biotherapy, and chemotherapy. Tumor-targeted therapies using radiolabeled octreotide and metaiodobenzylguanidine (mIBG) represent a novel treatment approach. The aim of this study was to evaluate the effectiveness of 131I-mIBG in the treatment of metastatic midgut carcinoid tumors. survival outcomes were assessed for patients treated at two regional cancer centers and then compared. One center used 131I-mIBG routinely in the management of metastatic carcinoid tumors (center A), and the other did not use this modality (center B). Only patients with histologically proven metastatic carcinoid tumor shown, or thought most likely, to be of midgut origin were included in the study. During the period 1980 to 2002, a series of 58 patients from center A with metastatic carcinoid tumor arising from the midgut underwent multimodality therapy with the addition of 131I-mIBG. Their median age was 64 years. The median dose of 131I-mIBG administered was 6751 MBq, and there was an average of 2.8 treatments per patient. During the same period, 58 patients with metastatic carcinoid were treated at center B with similar multimodality therapy without the use of 131I-mIBG therapy. Their median age was 65 years. Survivals at 3 and 5 years were 77% and 63%, respectively (95% CI 47-75), for group A. The 3- and 5-year survivals for group B were 56% and 47% (95% CI 34-59), respectively. The mean follow-up was 6.6 years for group A and 5.0 years for group B. Although retrospective in nature, this study suggests that the addition of 131I-mIBG therapy to the treatment protocol of patients with metastatic midgut carcinoid tumors prolongs survival.

Intertumoural variability in functional imaging within patients suffering from neuroendocrine tumours. An observational, cross-sectional study

(123)I mIBG (meta-iodobenzylguanidine) and (111)In pentetreotide scintigraphy imaging modalities are useful in demonstrating neuroendocrine tumours. Although (111)In pentetreotide is generally held to be a more superior imaging agent than (123)I mIBG for neuroendocrine tumours, we noted a differential uptake of the two agents by different tumour sites within individual patients. In some cases, the two tracers appeared to demonstrate different lesions within the same patient. The aim of this study wasto determine the positivity of the two imaging modalities, the degree of correlation between them and to highlight any clinically useful differences between the two modalities. (123)I mIBG and (111)In pentetreotide images of 149 consecutive, biopsy-proven or biochemically confirmed, neuroendocrine tumour patients were compared. All the patients underwent whole-body imaging and upper abdominal single-photon emission computed tomography (SPECT). The results of both types of imaging were compared, lesion by lesion, for each individual patient. The overall positivity rate for (111)In pentetreotide was 79%, and that for (123)I mIBG was 63%. When both agents were positive, the (111)In pentetreotide highlighted more lesions within the same patient in 33%, whilst the (123)I mIBG highlighted more lesions in 13%. In 12% of patients both agents were positive, but different lesions were seen with the two agents. (111)In pentetreotide has greater positivity than (123)I mIBG for imaging neuroendocrine tumours. However, the two modalities can highlight different tumour lesions, suggesting the presence of phenotypically diverse tumour populations within individual patients. These findings are likely to influence clinical management in the future.