Treatment of gastrointestinal endocrine tumours with interferon-alpha and octreotide

This paper reports on the results of two controlled therapeutic trials on patients with endocrine tumours of the gastrointestinal tract. Seventeen patients were treated up to 18 months with recombinant interferon-alpha 2c (2 x 10(6) IU/m2 s.c. daily) and 16 patients are treated in an ongoing study with octreotide (3 x 200 micrograms daily). Objective response (greater than 50% reduction of hormone secretion) was observed in one of 15 evaluable patients on IFN-alpha and in 12 of 16 patients on octreotide. Reduction of tumour size was not observed in these two trials. However, the majority of patients had stable tumour size during IFN-alpha and octreotide treatment despite progressive disease before. Subjective improvement due to reduction of symptoms such as flushing, diarrhea, and dermatitis was significantly more frequent after octreotide than after IFN-alpha. Of five endocrine tumour patients with progressive disease on IFN-alpha, three responded to subsequent treatment with octreotide while one had stable disease and one progressed. Two cases are reported from the authors' series of patients treated with octreotide before start of these trials. Complete remission of the tumour by low-dose (2 x 100 micrograms daily) octreotide was observed in one carcinoid patient. This remission has now lasted for four years. In one patient with liver metastasis of a VIPoma, who had become resistant to streptozotocin, his watery diarrhoea is now completely controlled with 100 micrograms octreotide s.c. every second day.