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Abstract : |
Carcinoid tumors, composed of monotonous sheets of small round cell with uniform nuclei and cytoplasm, derive from the diffuse neuroendocrine system. Pathologists cannot differentiate benign from malignant tumors based on histology. Most commonly, carcinoid tumors occur in: the appendix (40%), small intestine (27%), rectum (13%) and bronchi (12%). Carcinoid tumors synthesize numerous bioactive amines and peptides, including neuron specific enolase (NSE), 5-hidroxitryptamine (serotonin), 5-hydroxytriptophan, synaptosin, chromogranin A and C, substance P, tachykinins, and hormones such as ACTH, calcitonin and growth hormone–releasing hormone. Serotonin causes the typical carcinoid syndrome, associated with severe flushing attacks. For all patients with carcinoid syndrome, the 5-year survival is approximately 25%. The prognosis varies with the site of origin and extent of disease. Surgery is useful for patients with localized primary carcinoids or metastatic tumors that produce obstruction. Control of liver metastases by surgery is associated with a 5-year survival of 80%. Recent data continue to document that chemotherapy has not been effective in gastro-pancreatic neuroendocrine tumors. Chemotherapy with doxorubycin, 5-fluorouracil and streptozocin has a 30% partial response rate. Somatostatin analogues, such as octreotide (Sandostatin) LAR in doses of 20-30 mg IM every 3 to 4 weeks, have been able to control signs and symptoms of carcinoid syndrome and appear to have decreased tumor growth, obtaining stabilization of disease., |
