A carcinoid tumor is a type of slow-growing cancer that usually arises in the digestive system and is sometimes referred to as a neuroendocrine tumor. Carcinoid tumors are typically found in the appendix, small intestine, rectum, or lungs. These tumors are usually small, measuring less than two centimeters, and often go undetected until they metastasize. Carcinoid tumors may also be referred to as a neuroendocrine carcinoma, malignant carcinoid tumor, or a well-differentiated endocrine carcinoma.
Carcinoid tumors are usually composed of cells that produce hormones and can be divided into two types: functional and nonfunctional. Functional carcinoid tumors are those that produce hormones and cause a variety of symptoms, such as flushing, wheezing, and diarrhea. Nonfunctional tumors do not produce hormones and usually remain undetected until they become very large or spread to other parts of the body.
Carcinoid tumors can be treated with surgery, radiation therapy, and chemotherapy. The prognosis for patients with carcinoid tumors can vary depending on the stage of the tumor, its size, and how far it has spread. In some cases, the tumor can be cured with surgery alone, but in more advanced cases, further treatments may be necessary.