Carcinoid Signs and Symptoms
Signs and symptoms of carcinoid tumors depend on the site of origin, on whether or not the tumor has spread (metastasized), and on which hormones are produced by the tumor.
Carcinoid tumors that are confined to the GI tract may not cause symptoms (i.e., be asymptomatic) because the hormones produced by these tumors are released into the bloodstream and destroyed by the liver. In some cases, these tumors result in symptoms caused by obstruction, such as abdominal pain, weight loss, changes in bowel function (e.g., constipation, diarrhea), and GI bleeding.
Tumors that originate in or spread (metastasize) to areas other than the GI tract (e.g., liver, lungs, pancreas) produce hormones that are not destroyed in the liver. When excessive amounts of these hormones circulate through the body, carcinoid syndrome can result
Carcinoid patients have an increased risk for Cushing's syndrome, a disease caused by excess production of hormones by the adrenal glands; somatostatinoma syndrome, a condition caused by excess production of somatostatin; and additional cancerous (malignant) tumors.
Common sites of carcinoid metastases include lymph nodes, liver, lungs, and bone. The likelihood of metastasis varies according to the size of the tumor. In carcinoid tumors less than 1 cm, the rate of metastasis is about 15–25 percent; in tumors between 1 and 2 cm, the rate is about 58–80 percent; and in tumors larger than 2 cm, the rate is more than 70 percent.