Carcinoid tumors and syndrome.

Carcinoid tumors are very rare and originate mainly in the gastrointestinal tract. The tumor histology is ambiguous and malignancy is determined by metastases. Carcinoid tumors affect both sexes equally and have been found in all age groups. Many carcinoid tumors are found incidentally or from symptoms related to the hormones that the tumor produces. Carcinoid syndrome occurs when vast quantities of hormones are produced from GI carcinoid metastases or a non-GI primary tumor. The classic "carcinoid triad" associated with the syndrome includes flushing, diarrhea, and cardiac involvement. The hormone largely responsible for most of these symptoms is serotonin. Treatment consists of a wide-resection for local primaries and usually palliative, medical support for patients with metastases. The tumors are very slow-growing and patients have lived for up to 30 years after metastasis is diagnosed. Somatostatin analogue (lanreotide and octreotide) administration controls many of the carcinoid symptoms. Somatostatin is a naturally occurring gastrointestinal peptide (hormone) which can augment or counteract a wide variety of other peptides. This article provides an overview of carcinoid tumor and carcinoid syndrome including diagnosis and treatment. Aspects important to patient care will also be addressed.