endocrine and metabolic disorders
Carcinoid Syndrome
Treatment of Carcinoid Syndrome
Surgical resection Octreotideand other drugs for symptoms Resection of primary gastrointestinal and lung carcinoids is often curative. For patients with hepatic metastases, surgical debulking, while not curative, may relieve symptoms and, in certain instances, prolong survival. In addition, locoregional therapies for liver metastases could include transarterial chemoembolization (TACE), bland embolization, radioembolization with yttrium-90 microspheres, or radiofrequency ablation. Other promising treatments for metastatic or recurrent disease includeeverolimus, a mammalian target of rapamycin (mTOR) inhibitor, and newly developed peptide receptor radionuclides. Radiation therapy is unsuccessful, in part because of the poor tolerance of normal hepatic tissue to radiation. No effective chemotherapeutic regimen has been established. Combination treatment that includes streptozotocin, 5-fluorouracil, andcyclophosphamideis typically used only for symptomatic patients with grade 2 (intermediate grade) metastatic disease who are unresponsive to other therapies, or have high tumor proliferation rates. However, the response duration is short. Certain symptoms, including flushing, have been relieved by somatostatin analogs (which inhibit release of most hormones) without lowering urinary 5-HIAA or gastrin. Numerous studies have suggested good results with long-acting analogs of somatostatin includingoctreotideandlanreotide, which are the drugs of choice for controlling diarrhea and flushing. Octreotideis begun with about 50 mcg subcutaneously twice a day, increasing if needed up to 750 mcg total daily dose. After stabilizing for at least 2 weeks on the short-acting formulation, patients may be switched to a depot formulation ofoctreotide20 mg intramuscularly every 4 weeks, increasing if needed to a maximum of 30 mg.Lanreotideis a depot formulation given as 120 mg subcutaneously every 4 weeks. Flushing also can be treated with phenothiazines (eg,prochlorperazine5 to 10 mg orally every 6 hours orchlorpromazine25 to 50 mg orally every 6 hours). Histamine type 2 (H2) blockers may also be used.Phentolamine(an alpha-blocker) 5 to 15 mg IV has prevented experimentally induced flushes. Corticosteroids (eg,prednisone5 mg orally every 6 hours) may be useful for severe flushing caused by bronchial carcinoids. Diarrhea may be controlled by Codeine15 mg orally every 4 to 6 hours Tincture of opium 0.6 mL orally every 6 hours Loperamide4 mg orally as a loading dose and 2 mg after each loose bowel to a maximum of 16 mg/day Diphenoxylate 5 mg orally 4 times a day Peripheralserotoninantagonists (eg,cyproheptadine4 to 8 mg orally every 6 hours) Telotristat, atryptophanhydroxylase inhibitor, 250 mg orally 3 times a day Niacinand adequate protein intake are needed to prevent pellagra because dietarytryptophanis diverted toserotoninby the tumor. Enzyme inhibitors that prevent the conversion of 5-hydroxytryptophan toserotoninincludemethyldopa250 to 500 mg orally every 6 hours. 