The role of somatostatin analogues in the treatment of gastro-enteropancreatic endocrine tumours

Neuroendocrine (NE) cells fire involved in gastro-enteropancreatic (GEP) neoplasms. Biological markers, such as peptides hypersecreted by biologically active NE tumours, aid in the evaluation of response to treatment. For surgically untreatable NE neoplasms, the therapeutic approach remains undefined. Somatostatin analogues, particularly octreotide, call control the clinical effects of hormone overproduction in NE neoplasms and they have revolutionised individualised treatment, particularly for biologically active tumours. So far, like interferon, octreotide used al standard dosages has failed to control neoplastic growth per se. We gave the somatostatin analogue lanreotide to women with advanced breast cancer and to colorectal carcinoma patients. Results confirmed that inhibition of the production of insulin-like growth factor-1, which plays an important role in neoplastic proliferation, could be obtained using the highest doses. Considering these data, we started a clinical trial of 58 patients affected by NE tumours, treated with two sequential doses (500 and 1,000 mu g subcutaneously t.i.d.) of octreotide. Long-term disease stabilisation (> 6 months) was achieved in 43% of patients but an objective response in only 3%. Good control of clinical symptoms and markers was obtained in 73 and 77% of cases, respectively. Toxicity was negligible. Somatostatin analogues should be carefully evaluated at high doses for possible anti-proliferative effects. Studies are currently investigating their promising association with interferon.