The influence of groundwater chemistry on arsenic concentrations and speciation in a quartz sand and gravel aquifera)

Recent work suggests that between 50 and 75% of small-cell lung cancer (SCLC) tumours have specific high-affinity binding sites for somatostatin. This study evaluated the potential role of the radiolabelled somatostatin analogue, ["l'In]pentetreotide, in the detection and staging of SCLC in patients prior to and after chemotherapy using scintigraphic imaging techniques. Thirteen patients were studied prior to chemotherapy. Following standard staging six patients had limited stage disease and seven extensive disease. [I"'In]pentetreotide imaging led to the detection of all primary sites of disease, including a primary site of disease not detectable with chest radiograph or computerised tomography (CT) of the thorax. Five of ten metastatic sites detected by standard staging were also imaged. Furthermore, a cerebellar metastasis was detected in a patient thought to have disease confined to the right hemithorax. This was subsequently confirmed with a CT brain scan. Following chemotherapy ["'In]pentetreotide imaging detected residual intrathoracic disease in two of three patients with complete remissions by standard staging and in two patients who had had a partial response to chemotherapy. These results suggest that ["'In]pentetreotide imaging may have a role to play in the clinical evaluation of patients with SCLC. Specifically, this technique may be of particular value in detecting residual intrathoracic disease in patients thought to be in complete remission by conventional staging methods. Somatostatin is a tetradecapeptide that has a wide range of biological activities functioning as a hormone release-inhibitory factor, neurotransmitter, immunomodulator and endogenous inhibitor of cell growth 1989). Somatostatin acts by binding to specific receptors expressed by target tissues. Tumours with neuroendocrine features may express specific high-affinity binding sites for somatostatin (Reubi et al., 1990a). Experimental studies have clearly demonstrated that the majority of small-cell lung cancer (SCLC) tumours are neuroendocrine. SCLC is characterised by the expression of both pan-neuroendocrine markers and specific hormones and their receptors, including bombesin/gastrin-releasing peptide (GRP) and insulin-like growth factor 1 (IGF-1) (Cuttitta et Recent work has demonstrated that SCLC tumours may synthesise somatostatin and that between 50 and 75% have high-affinity somatostatin binding sites (Bepler et al. The radiolabelled somatostatin analogue ['231-tyr']octreo-tide has been successfully used in scintigraphic imaging to detect neuroendocrine tumours, including gastrointestinal and pancreatic APUDomas and paragangliomas (Krenning et al., 1989; Lamberts et al., 1990a,b; Kwekkeboom et al., 1991). However, it is an expensive preparation with very high hepatobiliary accumulation and a short effective half-life. Furthermore, difficulties in labelling tyr'-octreotide with 1231 mean that such scans …