Interferon-alpha versus somatostatin or the combination of both in gastro-enteropancreatic tumours.

Interferon-alpha (IFN-alpha) has a direct anti-tumour effect and is an immunomodulator. Somatostatin analogues, by contrast, when used to treat neuroendocrine tumours, control the secretion and peripheral effects of hormones, although at high doses they induce apoptosis. We have used IFN-alpha to treat > 350 patients with neuroendocrine tumours, and combining our and published data gives a median 44% biochemical response rate and 11% tumour response rate. Side-effects are mainly flu-like symptoms, then low-grade chronic fatigue syndrome. 15% may develop autoimmune reactions. The side-effects profile of somatostatin analogues is better but patients must take frequent injections and may have bile problems. We combined IFN-alpha and octreotide treatment in 24 patients with malignant carcinoid tumours who did not respond biochemically to high-dose (300 micrograms/day) octreotide alone. Biochemical response occurred in 77% but no significant anti-tumour effect was noted besides disease stabilisation in 4 cases. The combination therapy had an effect on clinical symptoms rather than tumour mass. Interferon was better tolerated when in the combination.