Plasma methoxytyramine: a novel biomarker of metastatic pheochromocytoma and paraganglioma in relation to established risk factors of tumour size, location and SDHB mutation status.
BACKGROUND
There are currently no reliable biomarkers for malignant pheochromocytomas and paragangliomas (PPGLs). This study examined whether measurements of catecholamines and their metabolites might offer utility for this purpose.


METHODS
Subjects included 365 patients with PPGLs, including 105 with metastases, and a reference population of 846 without the tumour. Eighteen catecholamine-related analytes were examined in relation to tumour location, size and mutations of succinate dehydrogenase subunit B (SDHB).


RESULTS
Receiver-operating characteristic curves indicated that plasma methoxytyramine, the O-methylated metabolite of dopamine, provided the most accurate biomarker for discriminating patients with and without metastases. Plasma methoxytyramine was 4.7-fold higher in patients with than without metastases, a difference independent of tumour burden and the associated 1.6- to 1.8-fold higher concentrations of norepinephrine and normetanephrine. Increased plasma methoxytyramine was associated with SDHB mutations and extra-adrenal disease, but was also present in patients with metastases without SDHB mutations or those with metastases secondary to adrenal tumours. High risk of malignancy associated with SDHB mutations reflected large size and extra-adrenal locations of tumours, both independent predictors of metastatic disease. A plasma methoxytyramine above 0.2nmol/L or a tumour diameter above 5cm indicated increased likelihood of metastatic spread, particularly when associated with an extra-adrenal location.


CONCLUSIONS
Plasma methoxytyramine is a novel biomarker for metastatic PPGLs that together with SDHB mutation status, tumour size and location provide useful information to assess the likelihood of malignancy and manage affected patients.
Institute of Clinical Chemistry and Laboratory Medicine, University of Dresden, Dresden, Germany. Graeme.Eisenhofer@uniklinikum-dresden.de
Graeme
G
Eisenhofer
Jacques W M
JW
Lenders
Gabriele
G
Siegert
Stefan R
SR
Bornstein
Peter
P
Friberg
Dragana
D
Milosevic
Massimo
M
Mannelli
W Marston
WM
Linehan
Karen
K
Adams
Henri J
HJ
Timmers
Karel
K
Pacak
D000310:Adrenal Gland Neoplasms / Q000235:genetics / Q000473:pathology*; D000328:Adult; D014408:Biomarkers, Tumor / Q000097:blood*; D004298:Dopamine / Q000031:analogs & derivatives* / Q000097:blood; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D009647:Normetanephrine / Q000097:blood; D010235:Paraganglioma / Q000235:genetics / Q000473:pathology / Q000556:secondary*; D010673:Pheochromocytoma / Q000235:genetics / Q000473:pathology / Q000556:secondary*; D012307:Risk Factors; D013385:Succinate Dehydrogenase / Q000235:genetics*
D014408:Biomarkers, Tumor; D009647:Normetanephrine; C108095:SDHB protein, human; D013385:Succinate Dehydrogenase; C001746:3-methoxytyramine; D004298:Dopamine