The importance of the measurement of circulating markers in patients with neuroendocrine tumours of the pancreas and gut.

The measurement of general and specific biochemical markers in patients with neuroendocrine tumours assists with diagnosis and gives an indication of the effectiveness of treatment and they may be used as prognostic indicators. There is much agreement that chromogranin A is the most universally helpful marker; it is found to be elevated in the circulation of about 90% of patients with metastatic neuroendocrine tumours and there are several excellent commercially available kits which give reliable estimations. Specific markers are useful for diagnosis also, and are helpful indicators of the effectiveness of treatment, particularly where tumour bulk may not change as much as tumour activity. Sporadic pancreatic neuroendocrine tumours may secrete more than one peptide and this indicates a worsening prognosis. Because of the wide variation in the progression of neuroendocrine tumours, a prognostic indicator gives a significant advantage to the clinician in order to facilitate optimum treatment at the optimum stage of disease. Both chromogranin A and neurokinin A have been used as powerful prognostic indicators for midgut carcinoid tumours.