The role of interferons in the management of carcinoid tumors.

Malignant carcinoid tumors with the carcinoid syndrome has over the years presented a therapeutic challenge. Surgery is 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 benefit, whereas a new somatostatin analogue octreotide gives a good control of clinical symptoms but not of tumor progression. Interferon treatment was introduced in 1982 by our group and we are now presenting results of medical treatment in 130 patients with histologically verified malignant carcinoid tumors and liver metastases. One hundred and eleven patients were treated with alpha-interferon, whereas 19 patients received conventional chemotherapy. Forty-seven out of 111 patients (42%) treated with alpha-interferon demonstrated a significant biochemical response and 15% also more than 50% reduction of tumor size. In another 43 (39%) patients stabilization of the carcinoid disease was noted whereas 21 (19%) showed progressive disease. The median duration of response was 34 months. Subjective response with improvement of diarrheas, flush and/or bronchoconstriction was noticed in 76 patients (68%). Among the 19 patients treated with conventional chemotherapy only 2 showed biochemical response and it lasted only for 3-5 months. The patients treated with chemotherapy had a median survival of only 8 months compared with 80+ months in the group treated with alpha-interferon. The adverse reactions of alpha-interferon are manageable and consist mainly of fatigue, weight reduction and reduction of blood cell counts. Neutralizing interferon antibodies might occur in patients treated with recombinant alpha-interferons (5-15%).