MEDICAL-TREATMENT OF NEUROENDOCRINE TUMORS

Background: Tumors of the neuroendocrine system are characterized by a mine precursor uptake and decarboxylation, and they represent a hetero geneous group of carcinomas including carcinoids, islet cell carcinoma s of the pancreas, medullary thyroid carcinomas and Merkel cell carcin omas. Their similar cytochemical and ultrastructural properties sustai n the hypothesis of a common embryologic origin within the neural cres t. Many of these tumors grow slowly, and reducing tumor burden represe nts the treatment of choice. However, when surgery is not feasible, me dical treatment has to be considered. Therapeutic approaches in metast atic disease often do not consider the different biologic behaviors of these neoplasms. Moreover, efficacy of the treatment is associated wi th lack of a clear definition of the type of response: objective, symp tomatic or biochemical. Methods: In this review we have analyzed the d ifferent medical approaches used in the treatment of neuroendocrine tu mors in an attempt to define their precise role in the different neopl asms. Results: In carcinoid tumors, immunotherapy and the somatostatin analogue can be efficaciously used for the control of carcinoid syndr ome. For inhibition of tumor growth, chemotherapy should be used only in patients with rapidly progressive disease, and the results are stil l unsatisfactory. Conclusions: Although all these tumors appear to hav e similar cytochemical properties, the responsiveness of the various n eoplasms is very different. In the future, a specific treatment modali ty and a clear definition of the type of response (objective, symptoma tic or biochemical) need to be defined for each type of neuroendocrine tumor.