Treatment of metastatic carcinoid tumour with recombinant interferon alfa

14 patients with metastatic carcinoid tumour were treated with recombinant interferon alfa 6-30 x 10(6) IU weekly for 3-25 (median 6.5) months. A decrease in the 24-h urinary 5-hydroxyindoleacetic acid (5-HIAA) level to less than 50% of the pretreatment value was observed in 5 of the 10 cases with an elevated urinary 5-HIAA level. In 4 of the 5 remaining patients, the 5-HIAA level decreased 30-50% from the pretreatment value. 5 of the 9 evaluable patients with carcinoid syndrome experienced symptomatic relief, but none became symptom-free. Severe toxicity was not observed. The median time to progression was 4.5 months, and, in patients with a greater than 50% decrease in 24-h urinary-5-HIAA, it was 17 months. Objective regression in tumour size could not be demonstrated in any of the patients.