Background: Chromogranin A (CgA) is a secretory protein present in dense-core vesicles of neuroendocrine (NE) cells. Its ubiquitous presence in NE tissues makes it a suitable circulating marker of neoplasms of NE origin.Patients and Methods: Plasma CgA was determined in 178 patients with NE tumors and in 36 patients with non-endocrine malignancies. Circulating CgA was also serially evaluated in 39 NE cancer patients with advanced disease submitted to systemic therapy and in 14 patients with no evidence of disease (NED).Results: Supranormal CgA values were found in 81% of patients with advanced NE tumors and in only 91% of NED cases. Plasma CgA in patients with well differentiated NE tumors, such as carcinoids, carcinoma of gastrointestinal tract, pheocromocytoma, pancreatic NE carcinoma (either functioning or not functioning), medullary thyroid carcinoma and NE tumors from various primary sites, was higher and more frequently elevated than in patients with small-cell lung cancer (P < 0.001). Plasma CgA did not discriminate patients with NE from those with non NE neoplasms since it was found elevated in 44% of the latter cases. Plasma CgA pattern correlated with the disease response in patients submitted to cytotoxic treatment and with changes in clinical symptomathology in patients receiving somatostatin analogs.Conclusions: Our data confirm that CgA is the best circulating neuroendocrine marker available up to now available for the management of differentiated neuroendocrine malignancies irrespective of tumor location and functional status. CgA plasma levels could also identify the coexistence of neuroendocrine differentiation in the context of non-endocrine malignancies. Circulating CgA seems to be less useful in undifferentiated tumors such as small-cell lung cancer.

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.

BACKGROUND The alteration of the bone microenvironment as a consequence of skeletal metastases is poorly understood. The aim of this study was to search for patterns of bone markers in relation to primary tumor type, bone pain, and number of sites involved in patients with bone metastases. METHODS We studied 323 patients with bone metastases from various primary malignancies. We sequentially measured the serum concentrations of bone alkaline phosphatase [by an electrophoretic technique (BALP)], carboxy-terminal telopeptide of type I collagen (ICTP), calcium (CaS), intact parathyroid hormone (PTH), and the fasting urinary excretion of calcium (Ca:Cr). Immunoradiometric serum bone alkaline phosphatase (I-BALP) and urinary excretion of deoxypyridinoline (DPYD) were also assessed in the 175 cases. Data were analyzed as a function of bone pain (assessed by a validated pain questionnaire), the number of radiographically confirmed sites of bone involvement, and the most frequent primary tumor types: breast cancer (BC; 124 patients), prostate cancer (PC; 90 patients), and non-small cell lung cancer (LC; 49 patients). RESULTS Serum BALP and I-BALP correlated with the number of radiologically identified blastic bone lesions. BALP and I-BALP were more frequently increased in PC (72% for both measurements) than in BC (50% and 60%, respectively) or LC (3% and 5%, respectively; P <0.001 for BALP and P = 0.001 for I-BALP). ICTP and DPYD values did not differ among PC, BC, and LC, but they did show a direct relationship with the disease extent in bone (P <0. 001). CaS and Ca:Cr did not vary significantly according to the bone tumor burden. Bone pain directly correlated with ICTP (P <0.001), DPYD (P = 0.002), CaS (P <0.002), and Ca:Cr (P = 0.001), whereas the relationship was inverse for serum PTH (P = 0.002). When patients were stratified according to the primary tumor, ICTP correlated with the bone pain in all subsets (P <0.005, <0.005, and <0.001 for BC, PC, and LC, respectively), as did CaS and Ca:Cr in LC patients (P = 0.01 and 0.02, respectively) but not in PC and BC patients. CONCLUSIONS The patterns of bone turnover markers differ among the primary tumor types. Both resorption and formation markers reflect the number of radiographically identified sites of bone metastases, whereas resorption markers and serum calcium but not formation markers correlate with bone pain.