Laboratory tests for neuroendocrine tumours.

: Neuroendocrine tumours (NETs) often have a good prognosis and have peculiar biological characteristics, among which the ability to produce and release biologically active substances. Hypersecretion of hormones, biogenic amines or growth factors often cause severe syndromes that are very debilitating. Now sensitive assays for the measurement of these substances have been developed and this has improved the possibility of patient follow-up by means of in vitro examinations. The decision about which in vitro examination to be utilised for NET management is very difficult because of the NET low incidence, the very large number of measurable hormones, the difficulty or low patient compliance for some diagnostic tests. In this review we describe the most useful laboratory tests for determining the diagnosis of NET, their prognostic significance and the clinical value of specific marker evaluation in the follow-up of the NET patient. Particular consideration has been given to biomarkers for gastroenteropancreatic and sympatho-adrenal system tumours and for prostate and breast cancers with neuroendocrine differentiation.