Abstract
Findings from five independent studies - with close to 350 patients with pheochromocytoma and more than 2 500 in whom the tumor was excluded - indicate that measurements of plasma free metanephrines provide an overall diagnostic sensitivity of 98% and specificity of 92%. The recommendation that initial testing for the tumor should always include measurements of either plasma or urinary fractionated metanephrines results from recognition of the high diagnostic sensitivity of measurements of plasma metanephrines. The few patients with pheochromocytoma in whom the test may not yield a positive result include those with very small tumors or microscopic disease and others with tumors that do not produce norepinephrine and epinephrine. Such patients are typically normotensive and do not exhibit symptoms of catecholamine excess. Additional measurements of methoxytyramine can be useful for detecting those tumors that produce only dopamine. Suboptimal diagnostic specificity and difficulties in distinguishing true- from false-positive elevations of plasma metanephrines remain challenges for diagnosis. Improvements in analytical technology (e.g., liquid chromatography with tandem mass spectrometry) and new strategies for follow-up testing provide possible solutions to these problems. The single most important remaining clinical care challenge is the development of effective cures for patients with malignant disease. Current treatments, none of which are truly satisfactory, include chemotherapy and radiopharmaceutical therapy with 131 I-labelled m -iodobenzylguanidine or radioactive somatostatin analogues. Improvements in treatment may in the future come from several fronts, but proof of efficacy ideally will require well-coordinated multicenter prospective trials in larger numbers of patients than in previous studies.
Key words
pheochromocytoma - paraganglioma - metanephrines -
m -iodobenzylguanidine - malignant pheochromocytoma - metastases
References
131 I-metaiodobenzylguanidine (131 I-MIBG).
Ann N Y Acad Sci.
2006;
1073
465-490
131 I]Meta-Iodobenzyl Guanidine, for the treatment of tumours transfected with the noradrenaline transporter gene.
Lett Drug Des Discovery.
2004;
1
1-5
131 I-MIBG.
J Nucl Med.
2005;
46
2112-2116
211 At]astatobenzylguanidine in an athymic mouse human neuroblastoma xenograft model.
Nucl Med Biol.
1996;
23
851-856
211 At]astato-4-fluorobenzylguanidine: a potential therapeutic agent with prolonged retention by neuroblastoma cells.
Br J Cancer.
1997;
76
226-233
211 At]MABG.
Bioorg Med Chem.
2007;
15
3430-3436
131 I meta-iodobenzylguanidine.
Gene Ther.
1999;
6
1147-1152
18 F]-fluoro-2-deoxy-D-glucose in 6-[18 F]-fluorodopamine- and [(123)I]-metaiodobenzylguanidine-negative metastatic pheochromocytoma sites.
Nucl Med Commun.
2006;
27
31-36
Correspondence
graeme.eisenhofer@uniklinikum-dresden.de
