In the treatment of carcinoids, lanreotide, a long-acting somatostatin analog administered every 10 to 14 days, has an efficacy similar to that of octreotide and an agreeable formulation for patient use. The effects of lanreotide on symptom relief are comparable to those of octreotide, with 75% to 80% of patients reporting decreased diarrhea and flushing; however, there appears to be little improvement in tumor responses over shorter-acting octreotide. Depot formulations include long-acting repeatable (LAR) octreotide and a slow-release depot preparation of lanreotide. One study comparing subcutaneous short-acting octreotide with monthly LAR octreotide reported an increased median survival from the time of metastatic disease diagnosis (143 months vs. 229 months in favor of the LAR form), representing a 66% lower risk for death among patients treated with the LAR formulation. A randomized controlled study in metastatic midgut neuroendocrine tumors showed improved time to tumor progression with monthly LAR octreotide compared with placebo. (Refer to the Jejunal and Ileal carcinoids section in the Treatment Option Overview section of this summary.)
The typical duration of treatment with somatostatin analogs is approximately 12 months because of the development of tachyphylaxis (reported less frequently with long-acting formulations) and/or disease progression.[15,16,17] In the management of carcinoid crises, intravenous somatostatin analogs are effective; crises are usually precipitated by anesthesia, surgical interventions, or radiologic interventions. Adverse effects of somatostatin analog administration include:[19,20]
Biliary sludge and cholelithiasis occur in as many as 50% of the patients, but few patients (1%–3%) develop acute symptoms requiring cholecystectomy.
The most researched interferon in the treatment of carcinoid disease is interferon-alpha (IFN-alpha); comparable to somatostatin analogs, the most pronounced effects of IFN-alpha are inhibition of disease progression and symptom relief, with approximately 75% of patients reporting the resolution of diarrhea or flushing. IFN-alpha, similar to other IFNs studied in the treatment of carcinoids (e.g., IFN-gamma and human leukocyte interferon), has substantial adverse effects, including alopecia, anorexia, fatigue, weight loss, fever, a flu-like syndrome, and myelosuppression; however, IFN-alpha may show greater antitumor activity than somatostatin analogs. Both single-agent and multiagent chemotherapeutics appear to have little role in the management of these essentially chemoresistant tumors; no protocol has shown objective tumor response rates greater than 15%.