Chemotherapy and biotherapy in neuroendocrine tumors

Neuroendocrine gut and pancreatic tumors have over the years presented a therapeutic challenge. The patients present with a wide range of clinical symptoms related to hormone production that can sometimes be easily managed but are sometimes life threatening. The most frequent clinical symptom related to endocrine gut tumors is the carcinoid syndrome, with flushing, diarrhea, bronchoconstriction, and right heart failure. Until the middle of the 1980s, when a patient was not cured by surgery, very little could be offered except chemotherapy. Biotherapy has revolutionized the treatment of malignant neuroendocrine gut and pancreatic tumors, in which both interferon-alpha and somatostatin analogues improved the quality of life for these patients and possibly also increased survival. Chemotherapy, with response rates of 40% to 60% in endocrine pancreatic tumors, is still first-line treatment in this group of patients, whereas in patients with carcinoids of the gut, no beneficial value of chemotherapy so far has been noticed. Both interferon-alpha and somatostatin analogues provide biochemical responses in 40% to 70% of patients with carcinoid tumors, whereas significant tumor reduction is only noticed in a few cases. Development of biotherapy is just at its beginning, and in the future, when we have learned more about tumor biology and mechanisms of action of these treatments, even better therapeutic results might be encountered. Combinations of biotherapy with chemotherapy as well as combinations of different biotherapies are now under clinical investigation.