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PTU-159 Variable Utility Of Chromogranin A Assays In The Diagnosis Of Gastric Carcinoid Type 1
  1. RE Rossi1,2,
  2. NG Martin3,
  3. J Garcia-Hernandez1,
  4. D Mandair1,
  5. M Mullan1,
  6. C Toumpanakis1,
  7. ME Caplin1
  1. 1Neuroendocrine Tumour Unit, Centre for Gastroenterology, Royal Free Hospital, London, UK, London, UK
  2. 2Postgraduate School of Gastroenterology, Universita’degli Studi Di Milano, Milan, Italy
  3. 3Department of Clinical Biochemistry, Royal Free Hospital, London, UK

Abstract

Introduction Chromogranin A (CgA) is used in the diagnosis and follow-up of patients with neuroendocrine tumours, whilst there is debate over the accuracy of CgA assays in gastric carcinoid type 1 (GC1). Clinical interpretation of CgA results may be affected by the heterogeneity between available assays. The commercial CgA assay, DAKO (DAKO, Denmark A/S, Glostrup, Denmark) is an ELISA which recognises a 23 kD C terminal fragment of CgA; the Imperial Supra-regional Assay Service radioimmunoassay (SAS Hammersmith Hospital, Imperial College, London) is a competitive radioimmunoassay raised against the whole pancreastatin molecule. Present study is aimed at comparing CgA-DAKO and CgA-SAS to determine their accuracy in the diagnosis of GC1.

Methods Patients with a confirmed diagnosis of GC1 and available plasma CgA measurements according to two different assays (SAS, DAKO) were included and retrospectively reviewed. CgA values were ranked in 4 groups: 1. normal values, 2. increase <2 upper limit of normal (ULN), 3.increase between 2–5 ULN, 4. increase >5 ULN.

Results 26 patients, 17 female and 9 male, mean age 55 years ± 11.75, were identified. At diagnosis, median CgA-DAKO were significantly higher than median CgA-SAS (81, normal range <27 IU/l versus 34.5 pmol/l, normal range <60 pmol/l, T=35.5, p < 0.001). When ranking the data, the results confirmed median CgA-DAKO significantly higher than median CgA-SAS: 3 vs. 1, T=0, p < 0.001. Sensitivity was 77% and 7.7% for CgA-DAKO and CgA-SAS, respectively.

Conclusion CgA-DAKO shows a better sensitivity than CgA-SAS for the diagnosis of GC1. Accurate diagnostic biomarkers may identify those patients who may benefit from a closer endoscopic follow-up in cases of raised neuroendocrine markers. Further prospective studies are needed highlighting the difference in diagnostic sensitivity between assays.

References

  1. Ramachandran R, et al. Improved diagnostic accuracy for neuroendocrine neoplasms using two chromogranin A assays. Clin Endocrinol (Oxf). 2012;76:831–836

  2. Baudin E, et al. Impact of chromogranin-A measurement in the work-up of neuroendocrine tumors. Ann Oncol 2001;12(Suppl 2): S79–S82

  3. Stridsberg M, et al. A comparison between three commercial kits for chromogranin A measurements. Journal of Endocrinology 2003:177:337–341

  4. Ardill JES. Circulating markers for endocrine tumours of the gastroenteropancreatic tract. Annals of Clinical Biochemistry 2008:45, 539–559

Disclosure of Interest None Declared.

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