Carcinoid tumors, also known as well-differentiated neuroendocrine tumors (NETs), develop in the gastrointestinal system, the lungs, and, in rare cases, the genitourinary tract. They are a form of neuroendocrine tumor with distinct biology and clinical characteristics. The treatment of the carcinoid tumor is varied. When the original tumor has not yet spread, it is customary to remove it surgically. If the tumor has spread or is accompanied by symptoms (carcinoid syndrome, diarrhea, flushing, etc...) the treatment includes administration of drugs, which I detail in my article.