The role of interferons in the management of carcinoid tumours

Malignant carcinoid tumours with the carcinoid syndrome has over the years presented a therapeutic challenge. The patients might not only die from tumour progression but also from symptoms relating to hormone overproduction and the specific cardiac disease, e.g. right heart fibrosis and failure. Surgery has been the treatment of choice in local disease, but when liver metastases have developed other treatment procedures must be considered. Conventional chemotherapy has been of little beneficial value, with response rates of only 10-30%, whereas a new somatostatin analogue, octreotid, is effective in controlling clinical symptoms but not tumour progression. Interferon treatment was introduced in 1982 by our group, and we are now presenting treatment results of 130 patients with histologically verified malignant carcinoid tumours and liver metastases. One hundred and eleven patients were treated with a median dose of 6 mega units (MU) of interferon alpha, five times weekly (dose range 3-9 MU), whereas 29 patients received conventional chemotherapy. Forty-seven out of 111 patients (42%) treated with interferon alpha demonstrated a significant biochemical response and 15% demonstrated more than 50% reduction in tumour size. In another 43 (39%) patients stabilization of the carcinoid disease have been noted, whereas 21 (19%) showed progressive disease. The median duration of response was 34 months. Subjective responses with improvement of diarrhoea, flush and/or bronchoconstriction were noticed in 76 patients (68%). The 19 patients treated with chemotherapy demonstrated only 10% biochemical response, lasting for only 3-5 months. The survival analysis demonstrates a median survival of only 8 months in the group of patients treated with chemotherapy, compared to 80+ months (P less than 0.001) in the groups treated with interferon alpha. Interferon adverse reactions of fatigue, weight loss and anaemia were manageable. Neutralizing interferon antibodies were documented in 5-15% of the patients. Interferon alphas are active in patients with malignant carcinoid tumours. Clinical symptoms are significantly reduced following reduction of circulating hormones. Interferon might also have an impact on survival in this group of patients. The side-effects are moderate and managed by dose adjustments.