The quarterly journal of nuclear medicine : official publication of the Italian Association of Nuclear Medicine (AIMN) [and] the International Association of Radiopharmacology (IAR)最新文献

A revised clinicopathological classification of neuroendocrine tumors of the gastroenteropancreatic tract has been recently developed under the auspices of the World Health Organization (WHO) according to advances in the field of tumor biology. Here the classification is briefly outlined and discussed together with the guidelines for a correct approach to the histopathological diagnosis of neuroendocrine tumors and the interpretation of the classification schemes covering clinical (hyperfunctional syndromes included), pathological and biological patterns, with special emphasis on tumor prognosis.

Background: 45 patients with neuroendocrine tumours (22 neuroblastomas, 10 phaeochromocytomas, 3 para-gangliomas, 6 medullary thyroid carcinomas and 4 carcinoids) underwent 131I-MIBG therapy.

Methods: All patients, with the exception of 5 phaeochromocytoma cases with nonoperable disease, had previously been treated with conventional therapies. Patients had a previous diagnostic scintigraphy with 131I-MIBG (activity 20-44.4 MBq) or with 123I-MIBG (activity 74-222 MBq). The therapeutic activity for adults ranged from 3.7 to 7.4 GBq of 131I-MIBG; for children from 2.7 to 5.5 GBq. All treatments were repeated at not less than 4-weekly intervals. The neuroblastoma patients were divided into two groups: the first included 14 patients with advanced metastatic disease not responding to previous treatments; the second included 8 patients with documented residual neuroblastoma tissue that could not be surgically removed after first-line therapy.

Results: In neuroblastoma patients with advanced disease resistant to previous therapies 2 out of 14 showed a partial response, 9 stable disease and 3 progression of cancer. In neuroblastoma patients with residual disease (7 evaluable out of 8) we obtained 3 partial responses; a stable response was observed in 3 patients. The results of MIBG therapy in the group of phaeochromocytoma patients (9 evaluable out of 10) consisted of 3 partial responses, 5 stable disease and 1 progression. Evaluation of the response carried out on the basis of biochemical parameters increased the responses and MIBG therapy showed good effectiveness in controlling the functional symptoms. In the group of paraganglioma patients we observed 1 complete, 1 partial and 1 stable response. In patients with medullary thyroid carcinoma a partial response was observed in 1 patient with mediastinal metastases and 2 disease stabilisations were seen in another 2 patients. Patients with carcinoids who underwent MIBG therapy showed 3 disease stabilisations. The overall toxicity was acceptable, especially considering that the majority of our patients had had previous myelotoxic treatments (chemotherapy and/or radiotherapy, alone or in combination).

Conclusions: On the basis of our experience we can conclude that 131I-MIBG therapy is effective and also well tolerated.

111In-pentetreotide (Octreoscan) and other radiolabeled somatostatin analogs are useful in the management of well differentiated neuroendocrine malignancies such as carcinoid or islet cell neoplasms. These radiopeptides bind to membrane bound somatostatin receptors (sst 1-5) which are over-expressed in a wide variety of neoplasms, especially those arising from the neuroectoderm. Imaging advances allow for the noninvasive determination of the presence of sst receptors by combining radioactivity [111Indium with a somatostatin analog, DTPA-D-phe1-octreotide (pentetreotide)]. Radiolabeled somatostatin analogs bind to membrane receptors and internalization of the complex occurs. Auger emitting somatostatin analogs offer a novel and significantly less toxic approach to controlling neoplastic diseases by delivering targeted radiation specifically to receptor bearing cells while sparing receptor negative cells. Responses of 62-69% in 85 patients with metastatic neuroendocrine tumors treated with high dose (6-19.6 GBq) 111In-pentetreotide, specifically targeting tumor somatostatin receptors, have been reported. Objective responses observed included biochemical and radiographic responses with prolonged survival. This article will discuss and review the multi-center data available to date, the mechanisms of action of radiolabeled somatostatin analogs, dosimetry, clinical response parameters, and toxicity.

Neuroendocrine gastroenteropancreatic tumors are rather rare neoplasms with an incidence of 1-2 cases per 100,000 people. They show rather varying tumor biology and present sometimes distinct clinical symptoms such as flushing, diarrhoea, hypoglycemia and gastric ulcers. The biochemical diagnosis is today significantly improved by the introduction of chromogranin A as a general tumor marker, which is also useful in histopathology. Today the localization procedures include somatostatin receptor scintigraphy as the primary investigation together with CT or ultrasonography. The basis for treatment of neuroendocrine GEP tumors is not only a curative intent but merely amelioration of clinical symptoms, abrogation of tumor growth, maintaining and improvement of quality of life. Surgery has always to be considered in the treatment of neuroendocrine GEP tumors. It can be performed whenever during the course of the disease but it may be more productive in earlier stages. Liver dearterialization procedures can furthermore reduce the tumor masses in liver together with laser treatment or radiofrequency therapy. The medical treatment includes cytotoxic agents, alpha interferons and somatostatin analogues. Somatostatin analogues will always be combined with the other two alternatives to reduce clinical symptoms. Chemotherapy is particularly useful for patients with more aggressive tumors with high proliferation capacity, whereas alpha interferon is beneficial in classical midgut carcinoids with low proliferation capacity. Quite recently somatostatin based radioactive tumor targeted treatment has evolved with preliminary promising data but further studies are needed to deliniate its future role in the treatment of neuroendocrine tumors in patients.

In oncology there is an increasing interest in neuroendocrine tumors, whose incidence is generally considered low, although in a recent analysis of 5,468 cases there was an increase in the proportion of pulmonary and gastric carcinoids and a decrease in the appendiceal carcinoids. However carcinoid tumors are indolent and their diagnosis is often difficult to carry out, so the true incidence may be higher. Surgery remains the treatment of choice and it should always be considered in patients with neuroendocrine tumors although a complete cure is difficult to obtain. Cytotoxic chemotherapy is the medical treatment for highly proliferating neuroendocrine tumors, but it has showed a modest benefit. Somatostatin analogues, octreotide and lanreotide are the standard hormonal treatment for neuroendocrine tumors. Recently, two trials on lanreotide and octreotide have been published, and it is worth noting that in each trial a long-acting formulation has been used: for lanreotide a prolonged-release formulation (PR) which allows an injection of 30 mg every 2 weeks, and for octreotide a long-acting release formulation (LAR) which allows an injection of 10, 20 or 30 mg every 28 days. The results of each trial are very promising. However, there are methodological and clinical aspects which make it difficult to carry out new trials for studying neuroendocrine tumors. The increasing number of biological markers deserve further investigations before their wide use in clinical practice.

Radioiodine therapy is used in the treatment of patients with differentiated thyroid cancer both to ablate residual thyroid tissue after initial surgery and to treat residual, recurrent, or metastatic cancer. In most institutions, therapy remains based on empirically determined, fixed amounts of radioiodine that do not account for individual differences in the mass of tissue to be treated and in radioiodine kinetics. Over the last 25 years, we have developed and refined techniques based on pre-therapy, diagnostic quantitative radiation dosimetry and imaging with 131I that permit individualized treatment which balances the success of the treatment and the risk of serious acute adverse effects on the bone marrow and lungs. In this manuscript we discuss patient selection and preparation for radioiodine therapy and outline in detail methods for performing quantitative dosimetry studies. Guidelines for the application of these results to the treatment of individual patients are presented.

For more than 50 years, 131I has been recognized as an effective tool for controlling thyroid hyperplasia and hyperactivity. The fixed dose administration is the simplest method with doses of 111-370 MBq (3 to 10 mCi) 131I being administered. More sophisticated methods aiming to deliver a well-defined amount of 131I per gram of thyroid tissue are handicapped by problems related to the evaluation of the goiter size and the prediction of the sensitivity of thyroid cells to radiation. The use of 131I in nontoxic multinodular goiter is to be reserved for specific situations.

Pheochromocytomas and paragangliomas are rare catecholamine-producing tumors which arise from chromaffin tissue. When a pheochromocytoma/paraganglioma is suspected, biochemical confirmation is based on 24-hour urinary excretion rates of catecholamines and their metabolites (metanephrines, VMA, etc.). Following biochemical confirmation non invasive imaging techniques such as CT and/or MR of the abdomen and 123I-MIBG scintigraphy are performed to localize the tumor. 111In-octreotide may also be applied, mainly to localize head and neck chemodectomas. Malignant paragangliomas of either adrenal or extra-adrenal origin show a variable natural history: from a locally invasive indolent tumor to a highly aggressive malignancy. Surgery with complete resection or debulking of the primary tumor is the standard treatment. External radiotherapy and chemotherapy are usually scarcely effective. An alternative treatment is 131I-MIBG therapy which is performed with high specific activity 131I-MIBG. Usually a standardized dose ranging from 3.7 to 9.1 GBq of 131I-MIBG is administered by slow i.v. infusion. In advanced stage cases 131I-MIBG therapy aims at symptom palliation and tumor function reduction as well as at tumor arrest or tumor regression. In these cases MIBG therapy allows prolonged survival and good quality of life. In less advanced cases the purpose of MIBG therapy is to complement surgery and to achieve the total eradication of the tumor. Non functioning malignant paraganglioma can some time also concentrate MIBG and can be treated with high doses of the tracer. 131I-MIBG therapy is a safe treatment and is usually well tolerated by the patient (with rather low myelotoxicity).

Unlabelled: Peptide receptor scintigraphy with the radioactive somatostatin-analogue [111In-DTPA0]octreotide (DTPA = diethylenetriaminepentaacetic acid) is a sensitive and specific technique to show in vivo the presence and abundance of somatostatin receptors on various tumors. With this technique primary tumors and metastases of neuroendocrine cancers as well as of many other cancer types can be localised. A new application is the use of peptide receptor radionuclide therapy, administrating high doses of 111In- or 90Y-labeled octreotide-analogues. PRECLINICAL: We investigated the radiotherapeutic effect of 90Y- and 111In-labeled [DOTA0,Tyr3]octreotide (DOTA = tetraazacyclododecanetetraacetic acid) or [111In-DTPA0]octreotide in Lewis rats bearing the somatostatin receptor-positive rat pancreatic tumor CA20948 in A) the flank or B) in the liver.

Patients: Thirty end-stage patients with mostly neuroendocrine progressing tumors were treated with [111In-DTPA0]octreotide, up to a maximal cumulative patient dose of about 74 GBq, in a phase 1 trial. PRECLINICAL RESULTS: A) Flank model: at least two 111MBq injections of [111In-DOTA0,Tyr3]octreotide were needed to reach tumor response, in 40% of the animals complete tumor remission was found after a follow-up period of 10 months. One or two injections of [90Y-DOTA0,Tyr3] octreotide yielded transient stable disease. B) Liver model: we found that peptide receptor radionuclide therapy is only effective if somatostatin receptors are present on the tumors, and is therefore receptor-mediated. High radioactive doses of 370 MBq [111In-DTPA0]octreotide or 93 MBq [90Y-DOTA0,Tyr3]octreotide can inhibit the growth of somatostatin receptor-positive metastases.

Clinical results: There were no major clinical side effects after up to 2 years treatment, except that a transient decline in platelet counts and lymphocyte subsets can occur. Promising beneficial effects on clinical symptoms, hormone production and tumor proliferation were found. Of the 21 patients with progressive disease at baseline and who received a cumulative dose of more than 20 GBq [111In-DTPA0]octreotide, 8 patients showed stabilisation of disease and 6 other patients a reduction in size of tumors. There is a tendency towards better results in patients whose tumors have a higher accumulation of the radioligand.

Conclusion: Radionuclide therapy with octreotide-derivatives is feasible, both with 111In and 90Y as radionuclides.