In this issue Kouroumalis et al (see page 442) report extended survival in patients with hepatocellular carcinoma (HCC) treated with octreotide, a somatostatin analogue. Somatostatin is a cyclic peptide consisting of 14 amino acids which regulates growth hormone release. It is the product of a multigene family of peptides with two biological derivatives, namely somatostatin 14 and 28. Somatostatin regulates release of growth hormone, thyrotropin and acts as an autocrine and paracrine molecule to suppress neurotransmission, immunocyte activity, smooth muscle contractility, and uptake of nutrients. (reviewed by Lamberts et al 1). Somatostatin action is mediated through a specific receptor (SSR). Somatostatin suppresses pituitary and adrenal secretion of growth hormone or thyrotropin after surgery, and inhibits secretory activity of metastatic islet cell tumours such as vipoma, glucagonoma and metastatic carcinoid. It has also been reported to be beneficial in reducing splanchnic circulation and controlling bleeding from oesophageal varices, suppression of fluid secretion by pancreatic and enteric fistula as well as secretory diarrhoea.

Somatostatin receptors were identified recently in a variety of malignant tumours including lung and ovary carcinoma, adenocarcinoma of breast, kidney, colon, and even lymphomas.2-5 However, the heterogeneous expression of SSR on the various tumours makes assessment of the antitumour effect(s) of somatostatin difficult.6 Octreotide exerts a cell growth regulatory or suppressive effect in various tumours. This effect may operate through inhibition of growth hormone secretion, insulin and gastrointestinal hormones and/or direct effect(s) on production of insulin-like growth factor I or its binding proteins as well as direct inhibition of angiogenesis. On a molecular level, there is evidence that …