Use of m-[131I]iodobenzylguanidine in the treatment of malignant pheochromocytoma

Pheochromocytoma: 1926-1993

Pheochromocytoma is a tumor frequently sought and rarely found. It is associated with spectacular cardiovascular disturbances and, when correctly diagnosed and properly treated, it is curable; when undiagnosed or improperly treated, it can be fatal. Catecholamine-producing tumors that arise from chromaffin cells of the adrenal medulla and sympathetic ganglia are termed pheochromocytomas and paragangliomas, respectively. However, the term pheochromocytoma has become the generic name for all catecholamine-producing tumors. The biochemical diagnosis is straightforward. The localization of pheochromocytoma has been greatly facilitated by advances in computerized imaging and meta-iodobenzylguanidine scanning. Treatment with preoperative alpha- and beta-adrenergic blockade followed by surgical excision of the pheochromocytoma are associated with very low morbidity and mortality.

Imaging of catecholamine-secreting tumours: uses of MIBG in diagnosis and treatment

MIBG radiolabelled with 131I or 123I is a radiopharmaceutical which is concentrated in neuroendocrine tumours, particularly phaeochromocytomas and neuroblastomas. This permits non-invasive whole-body scintigraphic screening for benign and malignant, familial and sporadic, intra-adrenal and extra-adrenal phaeochromocytomas and primary and metastatic neuroblastomas, with high sensitivity (85-90%) and specificity (> 95%). MIBG is also concentrated in presynaptic terminals of adrenergic, autonomically innervated organs such as the heart, and may be used as a non-invasive in vivo probe to study this system. Large doses of 131I-MIBG and 125I-MIBG have been used experimentally to selectively deliver therapeutic doses of radiotherapy to malignant phaeochromocytomas and refractory advanced neuroblastomas.

Malignant pheochromocytoma: a series of 14 cases observed between 1966 and 1990

We report 14 patients (9 males, 5 females) aged 15-59 years, treated for malignant pheochromocytoma. These patients were observed during the 1966-1990 period along with 68 other patients presenting benign pheochromocytomas. From the initial general presentation of the 14 patients, two groups could be individualized. In seven patients, the initial presentation seemed benign. After the excision, the recovery was complete, but patients recurred on average 7.8 yr later (range 1-22 yr). Tumors were intraadrenal in six cases (5 single, 1 bilateral) and extraadrenal in one case. In the seven remaining patients, malignancy was evident from the first examination. The tumors were intraadrenal in 2 cases, extraadrenal in 5 cases. Frequency of extraadrenal locations (6/14) was in this series significantly higher than in benign forms (9/68). Diagnosis of malignancy was based on metastases in 12 cases (lymph nodes in 5, bones in 5, liver in 4, lung in 2, brain in 1) and on peritumoral extension in 2 cases. No biological specificity was detected in urinary excretion of catecholamines or its metabolites. In 6 patients so far studied, an uptake of 131I MIBG was found in the tumor and/or metastases. Four patients received therapeutic doses of 131I MIBG and in three of them, this treatment led to a good result within a follow-up range of 12 to 66 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Malignant pheochromocytoma: clinical, biological, histologic and therapeutic data in a series of 20 patients with distant metastases

Twenty patients, 16 males and 4 females, aged 11-76 yr, were treated for a metastatic pheochromocytoma at our institution between 1985 and 1990. A neurofibromatosis was associated in 4. Thirteen patients had a unilateral adrenal tumor, 3 had an extraadrenal retroperitoneal tumor, 2 had a bilateral adrenal pheochromocytoma, one had a unilateral tumor with a contralateral medullary hyperplasia and one an adrenal and an extraadrenal pheochromocytoma. Metastases occurred in all patients, at presentation in 11, 10 to 30 months later in 7, and 9 and 28 yr later, respectively in two. Histology did not afford conclusive evidence for malignancy. Catecholamine hyperproduction was present in all, predominantly affecting norepinephrine. Neuron Specific Enolase level was elevated in 11, Neuro-Peptide Y level in 9 and procalcitonin level in 11/18. High dopamine, methoxytyramine and homovanillic acid excretion levels seemed to correlate with large tumors or terminal stage. MIBG uptake was found in 16 after a diagnostic dose and in 1 only after a therapeutic dose. Surgery was performed on primary tumor in 18 and on distant metastase in 10. Iodine-131 MIBG therapy was performed in 11, among whom 9 were evaluable. Cumulative activity ranged from 100 to 711 mCi, in 1 to 6 courses. Symptomatic improvement occurred in 5 patients, stabilization was observed in 3 and tumor partial response in two, which lasted for 28 and 9 months, respectively terminating in a rapidly progressing disease with bone marrow involvement. Moderate myelosuppression occurred in 4 patients. Chemotherapy gave no response in 7 evaluable patients. Fourteen patients died with a median survival of 16 months from diagnosis of metastases (range 3-60). Response to therapy was poor and warrants further cooperative trials.

Radionuclide therapy revisited

Apart from its use in endocrinology and rheumatology, therapeutic nuclear medicine is developing rapidly as an additional treatment modality in oncology. Many different specific tumour-seeking radiopharmaceuticals are being applied both for diagnostic scintigraphy and treatment, using multiple routes and mechanisms to target radionuclides at tumours. After a brief introduction of some basic principles of radionuclide targeting, the therapeutic radiopharmaceuticals available are reviewed according to the accumulation site in relation to the cell nucleus; the results of their current clinical use for therapy are also reviewed. The response observed to a number of these applications, the non-invasiveness of the procedure and the relative lack of toxicity and late effects in comparison with chemotherapy and external beam radiotherapy make radionuclide therapy an attractive and realistic alternative in the management of malignant disease, as well as in the treatment of a few benign disorders.