The symptoms of NETs depend upon the site of the tumor and if the tumor releases excessive hormones. The general symptoms of gastrointestinal NETs are:
- Pain due to nerve or tissue compression from a growing tumor
- The feeling of a lump under the skin
- Unexplained weight loss
- Persistent feelings of fatigue and tiredness
- Diarrhea
- Anemia
- Heartburn
- Rectal bleeding
- Nausea and vomiting
- Pain or discomfort in the rectum or abdomen
- Intestinal obstruction
- Weight loss
Sometimes, the tumor releases significant serotonin and other substances in the blood. The condition is known as carcinoid syndrome. The patients experience the following symptoms due to carcinoid syndrome:
- Difficulty breathing
- Rapid or abnormal heartbeat
- Flushing of skin
- Damage to the heart
- Reduced blood pressure
