The clinical management of neuroendocrine tumors with long-acting repeatable (LAR) octreotide: comparison with standard subcutaneous octreotide therapy.

Neuroendocrine tumors are rare, occurring in less than 1% of the population. They are divided clinically into functionally active or non-active tumors. Functionally active tumors produce a variety of substances (mainly peptides or serotonin) that are responsible for symptoms and sometimes can lead to the death of the patient independently from tumor proliferation. The most important compounds that can control symptoms in these patients are somatostatin analogs. Native somatostatin is not suitable for long-term clinical application due to its short half-life. Therefore, synthetic drugs were developed with improved pharmacokinetic characteristics. The best-characterized analog, octreotide, has been successfully applied to patients with functioning tumors. Octreotide can ameliorate symptoms in 30%-70% of the patients, mainly through a direct inhibitory effect on hormone production from the tumors. There is little or no effect on tumor growth during octreotide therapy; clinical responses were recorded in only 10%-30% of the patients. Recently, significant improvement in the management of the disease has been demonstrated with long-acting repeatable (LAR) octreotide. This new formulation requires only one monthly intramuscolar injection, and shows better acceptability and patient compliance to therapy. Data available to date show superimposable results of both standard octreotide and LAR octreotide in controlling symptoms, lowering hormone and tumor marker levels, and in reducing tumor growth. The availability of long-acting molecules have permitted the exploration of high-dose therapy in increasing tumor shrinkage and prolonging survival. Although there is a clear dose-response trend, the published data are not conclusive and further investigations are needed. The possible lack of cross-resistance between LAR octreotide and a different analog, Lanreotide, is a very stimulating finding and this might lead to the development of new therapeutical strategies in the management of neuroendocrine tumors.

Circulating chromogranin A in the assessment of patients with neuroendocrine tumours. A single institution experience.

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.

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.

Differential patterns of bone turnover in relation to bone pain and disease extent in bone in cancer patients with skeletal metastases.

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.