This is a medical question of type : information 
 What is (are) Gastrointestinal Carcinoid Tumors ? 
 Key Points
                    - A gastrointestinal carcinoid tumor is cancer that forms in the lining of the gastrointestinal tract.     -  Health history can affect the risk of gastrointestinal carcinoid tumors.     - Some gastrointestinal carcinoid tumors have no signs or symptoms in the early stages.     -  Carcinoid syndrome may occur if the tumor spreads to the liver or other parts of the body.     - Imaging studies and tests that examine the blood and urine are used to detect (find) and diagnose gastrointestinal carcinoid tumors.    - Certain factors affect prognosis (chance of recovery) and treatment options.
                
                
                    A gastrointestinal carcinoid tumor is cancer that forms in the lining of the gastrointestinal tract.
                    The gastrointestinal (GI) tract is part of the body's digestive system. It helps to digest food, takes nutrients (vitamins, minerals, carbohydrates, fats, proteins, and water) from food to be used by the body and helps pass waste material out of the body. The GI tract is made up of these and other organs:         -  Stomach.    -  Small intestine (duodenum, jejunum, and ileum).    -  Colon.    -  Rectum.          Gastrointestinal carcinoid tumors form from a certain type of neuroendocrine cell (a type of cell that is like a nerve cell and a hormone -making cell). These cells are scattered throughout the chest and abdomen but most are found in the GI tract. Neuroendocrine cells make hormones that help control digestive juices and the muscles used in moving food through the stomach and intestines. A GI carcinoid tumor may also make hormones and release them into the body.   GI carcinoid tumors are rare and most grow very slowly. Most of them occur in the small intestine, rectum, and appendix. Sometimes more than one tumor will form.    See the following PDQ summaries for more information related to GI and other types of carcinoid tumors:         -  Non-Small Cell Lung Cancer Treatment.    -  Pancreatic Neuroendocrine Tumors (Islet Cell Tumors) Treatment.     -  Rectal Cancer Treatment.    -  Small Intestine Cancer Treatment.    -  Unusual Cancers of Childhood Treatment
                
                
                    Carcinoid syndrome may occur if the tumor spreads to the liver or other parts of the body.
                    The hormones made by gastrointestinal carcinoid tumors are usually destroyed by liver enzymes in the blood. If the tumor has spread to the liver and the liver enzymes cannot destroy the extra hormones made by the tumor, high amounts of these hormones may remain in the body and cause carcinoid syndrome. This can also happen if tumor cells enter the blood. Signs and symptoms of carcinoid syndrome include the following:         - Redness or a feeling of warmth in the face and neck.     - Abdominal pain.    - Feeling bloated.    - Diarrhea.    - Wheezing or other trouble breathing.    - Fast heartbeat.        These signs and symptoms may be caused by gastrointestinal carcinoid tumors or by other conditions. Talk to your doctor if you have any of these signs or symptoms.