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Confirming the Diagnosis

Diagnosing

A diagnosis of neuroendocrine tumours (NETs) may be based on the following^1,2:

• Clinical symptoms
• Tests that measure hormones, biochemical tumour markers, and other markers in the body
• Imaging tests, such as CT, MRI, ultrasound, and SRS

Two key markers of NETs are 5-hydroxyindoleacetic acid (5-HIAA) and chromogranin A (CgA).^3,4

Clinical diagnosis of carcinoid syndrome can be confirmed by biochemical testing of 5-HIAA and CgA levels. Biochemical testing may also be used to indicate disease severity and confirm symptom origins.^5,6

5-HIAA^5,7-10

• 5-HIAA is the primary metabolite of serotonin excreted by the kidneys. Patients with carcinoid syndrome have significantly elevated levels of serotonin and increased urinary excretion of 5-HIAA
• Measurement of 5-HIAA is a standard diagnostic test for this syndrome,
  with a sensitivity of 73% and a specificity of 100%
• An elevated 5-HIAA level is associated with a classic carcinoid syndrome
  of flushing, diarrhea, and carcinoid heart disease
• 5-HIAA can be measured with a reliable, 24-hour urine test that is specific
  to carcinoid tumours
  • Because plasma serotonin is highly variable over a 24-hour period, the 24-hour urinary 5-HIAA is preferred over plasma serotonin as a measure of biochemical activity in NETs

CgA^1,11-13

• The measurement of CgA, which is found throughout endocrine tissues,
  is considered the gold standard of biochemical tests for confirming the diagnosis of NETs and for following the course of the disease
• CgA testing is a fast, easy blood test for all major types of NETs
• There is a clear connection between tumour burden and serum CgA concentrations
• High levels of CgA in NET patients are indicative of high tumour burden

Diagnostic Imaging

Diagnostic imaging plays a key role in diagnosing and monitoring NETs. There are multiple imaging techniques available to diagnose, localise, stage, and monitor the progression of NETs^1,5,14-18:

Octreoscan™ (somatostatin receptor scintigraphy) of a patient with liver metastasis from a carcinoid tumour. The primary tumour located in the distal ileum also is present in the figure.

Ultrasonography of liver metastases from a patient with carcinoid tumour. Ultrasound-guided biopsy can be taken during this procedure. CT picture of liver metastases in a patient with an endocrine pancreatic tumour.

Read more about the treatment and management of GEP NETs.

References: 1. Modlin IM, Kidd M, Latich I, Zikusoka MN, Shapiro MD. Current status of gastrointestinal carcinoids. Gastroenterology. 2005;128:1717-1751.
2. Arnold A. Diagnosis and management of neuroendocrine tumors. Medscape Website. Available at: http://www.medscape.com/viewarticle/420088. Accessed January 2, 2009. 3. Oberg K. Biochemical diagnosis of neuroendocrine GEP tumor. Yale J Biol Med. 1997;70:501-508. 4. Oberg K, Kvols L, Caplin M, et al. Consensus report on the use of somatostatin analogs for the management of neuroendocrine tumors of the gastroenteropancreatic system. Ann Oncol. 2004;15:966-973. 5. Jensen RT, Doherty GM. Carcinoid tumors and the carcinoid syndrome. In: DeVita VT Jr, Hellman S, Rosenberg SA, eds. Cancer: Principles & Practice of Oncology. 6th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2001:1559-1574. 6. Rorstad O. Prognostic indicators for carcinoid neuroendocrine tumors of the gastrointestinal tract. J Surg Oncol. 2005;89:151-160. 7. McCormick D. Carcinoid tumors and syndrome. Gastroenterol Nurs. 2001;25:105-111. 8. Vinik A, Feliberti E, Perry R, Payne RLJ, Nakave A. Carcinoid tumors. Endotext.com Website. Available at: http://www.endotext.org/guthormones/guthormone2/guthormone2.html. Updated January 28, 2008. Accessed November 12, 2008. 9. Zuetenhorst JM, Taal BG. Metastatic carcinoid tumors: a clinical review. Oncologist. 2005;10:123-131. 10. Boushey RP, Dackiw APB. Carcinoid tumors. Curr Treat Options Oncol. 2002;3:319-326. 11. Oberg K. Carcinoid tumors: current concepts in diagnosis and treatment. Oncologist. 1998;3:339-345. 12. Taupenot L, Harper KL, O’Connor DT. The chromogranin secretogranin family. N Engl J Med. 2003;348:1134-1149. 13. Bajetta E, Ferrari L, Martinetti A, et al. Chromogranin A, neuron specific enolase, carcinoembryonic antigen, and hydroxyindole acetic acid evaluation in patients with neuroendocrine tumors. Cancer. 1999;86:858-865. 14. Balon HR, Goldsmith SJ, Siegel BA, et al. Procedure guideline for somatostatin receptor scintigraphy with ¹¹¹In-pentetreotide. J Nucl Med. 2001;42:1134-1138. 15. Hillel PG, van Beek EJR, Taylor C, et al. The clinical impact of a combined gamma camera/CT imaging system on somatostatin receptor imaging of neuroendocrine tumours. Clin Radiol. 2006;61:579-587.
16. Iobenquane Sulfate I 131 Injection [prescribing information]. Bedford, MA: CIS-US, Inc; 1999. 17. van der Lely AJ, de Herder WW. Carcinoid syndrome: diagnosis and medical management. Arq Bras Endocrinol Metab. 2005;49:850-860. 18. Shi W, Johnston CF, Buchanan KD, et al. Localization of neuroendocrine tumours with [¹¹¹In]DTPA-octreotide scintigraphy (Octreoscan): a comparative study with CT and MR imaging. Q J Med. 1998;91:295-301.