Neuroendocrine tumours of the gut: long-term therapy with the somatostatin analogue SMS 201-995.

Nine patients with metastatic neuroendocrine tumours of the gut were treated for over 100 days with the long-acting octapeptide of somatostatin, SMS 201-995. Two patients had unusually aggressive tumours (neuroendocrine tumours are typically slow-growing) with only modest elevation of tumour secretory products. SMS 201-995 was given in an attempt to slow tumour growth, but tumour size continued to increase. Three patients had glucagonomas and uncontrolled skin rashes, and four patients had VIPomas, which caused uncontrolled watery diarrhoea. SMS 201-995 was given principally to reduce hypersecretion of hormones from their tumours and to relieve symptoms. All the patients experienced rapid relief of their symptoms when SMS 201-995 treatment was introduced, and symptomatic control was maintained throughout treatment except in one patient, who required a supplementary procedure (pancreatic primary tumour embolization). Circulating peptide levels were initially suppressed, but continued suppression did not occur in every case despite good clinical control. It seems likely that SMS 201-995 has beneficial effects on target organs as well as suppressing the release of peptides from tumour tissue. The tumours did not grow during treatment. The analogue was well tolerated, most adverse effects being minor. Somatostatin inhibited insulin release, but in only one patient was there a slight deterioration of glucose tolerance. SMS 201-995 is therefore a useful therapeutic tool in the long-term management of patients with symptoms due to uncontrolled hormone secretion from neuroendocrine tumours.