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J Clin Endocrinol Metab. 2008 Apr;93(4):1246-53. doi: 10.1210/jc.2007-1946. Epub 2008 Jan 22.

Elevated cocaine- and amphetamine-regulated transcript immunoreactivity in the circulation of patients with neuroendocrine malignancy.

Author information

1
Department of Metabolic Medicine, Hammersmith Hospital, Commonwealth Building, 6th Floor, Imperial College London, London W12 0NN, United Kingdom. sbloom@ic.ac.uk

Abstract

CONTEXT:

Cocaine- and amphetamine-regulated transcript (CART) codes for a peptide widely distributed in nervous and endocrine tissues. CART immunoreactivity (CART-LI) has been detected in human insulinomas.

OBJECTIVE:

The objective of the study was to investigate the measurement of plasma CART-LI as a tumor marker of neuroendocrine malignancy.

DESIGN AND SUBJECTS:

Plasma CART-LI levels were measured in 401 patients with a range of diagnoses: neuroendocrine malignancy (n = 131), after removal of neuroendocrine malignancy (n = 27), without any form of tumor or renal impairment (n = 192), with renal impairment (n = 17) and with nonneuroendocrine tumors (n = 34). Chromatography methods were used to investigate CART-LI circulating in human plasma.

RESULTS:

The upper limit of normal calculated for CART-LI was 150 pmol/liter. Mean circulating plasma CART-LI among neuroendocrine tumor patients was 440 pmol/liter, 56% of subjects having levels greater than 150 pmol/liter. Measuring CART-LI in addition to chromogranin (Cg)-A improved the sensitivity for neuroendocrine malignancy from 85 to 91%, whereas combined use of CgA and CgB had a joint sensitivity of 89%. Of 38 patients with pancreatic neuroendocrine tumors, 71% had plasma CART-LI levels greater than 150 pmol/liter, increasing to 95% in those classified with progressive disease (n = 20, mean CART-LI 625 pmol/liter), compared with 80% for CgA. Chromatographic analysis suggests that circulating CART-LI is present as one major form, which may correspond to CART (62-102) or another unknown form.

CONCLUSIONS:

We demonstrate CART-LI as a specific tumor marker in patients with a range of neuroendocrine tumors. Used in combination with CgA, CART-LI measurement has the potential to improve sensitivity in diagnosis and follow-up of neuroendocrine tumors, in particular progressive pancreatic neuroendocrine tumors.

PMID:
18211969
PMCID:
PMC2729185
DOI:
10.1210/jc.2007-1946
[Indexed for MEDLINE]
Free PMC Article

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