Neuroendocrine tumors laboratory findings
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Neuroendocrine tumors Microchapters |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Laboratory Findings
Cells that receive hormonal messages do so through receptors on the surface of the cells. For reasons that are not understood, many neuroendocrine tumor cells possess especially strong receptors; for example, PETs often have strong receptors for somatostatin, a very common hormone in the body. We say that such tumor cells overexpress the somatostatin receptors (SSTRs) and are thus avid for the hormone; their uptake of the hormone is strong. This avidity for somatostatin is a key for diagnosis – and it makes the tumors vulnerable to certain targeted therapies.
The list of potential markers for GEP-NETs is long. Aside from the hormones of secretory tumors, the most important markers are
- Chromogranin A (CgA)
- Urine 5-hydroxy indole acetic acid (5-HIAA) (grade C)
- Neuron-specific enolase (NSE, gamma-gamma dimer)
- Synaptophysin (P38)
and other markers include
- Synaptobrevin (VAMP-1)
- Synapsin (1A, 1B, 2A, 2B)
- SV2
- Protein P65
- Protein S-100
- Protein gene product (PGP) 9.5
- Intermediate filaments (cytokeratins, vimentin, neurofilaments)
- Protein 7B2
- Chromogranin B (secretogranin I)
- Chromogranin C (secretogranin II)
- Pancreastatin
- Vasostatin
- Cytochrome b561
- Leu-7 (HNK-1)
- Calcitonin
- Human chorionic gonadotropin-alpha (HCG-α)
- Human chorionic gonadotropin-beta (HCG-β)
- Thyroid function tests (TFTs)
- Parathyroid hormone (PTH)
- Calcium
- Prolactin
- {Alpha}-fetoprotein
- Carcinoembryonic antigen (CEA)
- ß-human chorionic gonadotrophin (ß-HCG) (grade D)
- CGRP
- GRP
- PYY
- hCGα
- N Peptide K
- Neurokinin A
- Serotonin
- Neurotensin
- Motilin
- Substance P
- Histamine
- Catecholamines
- Dopa
- Various rarer peptide hormones
- Synaptotagmin
- HISL-19
and newer (as of 2005) markers include
- N-terminally truncated variant of heat shock protein 70 (Hsp70)
- CDX-2, a homeobox gene product
- Neuroendocrine secretory protein-55
Aside from their use in diagnosis, some markers can track the progress of therapy while the patient avoids the detrimental side-effects of CT-scan contrast.