Often doctors are unable to identify the location of the tumor, despite clinically evident carcinoid syndrome. Only in ten percent of cases can a tumor develop in the respiratory system and, accordingly, carcinoid syndrome. Signs in the lung will be nonspecific, and sometimes there will be none at all. This is due to the relatively small size of the tumor and the absence of metastasis. Patients seek help with an already advanced disease and, as a rule, not to an oncologist, but first to a therapist. He can treat bronchiolitis, asthma or respiratory failure for a long time and unsuccessfully until he suspects the presence of an oncological process.

If this does not happen, the cell will multiply, create millions of copies of itself and begin to distribute toxic substances and hormones throughout the body. With such a set of disorders, it is difficult to suspect carcinoid. There is no exhaustion, sudden weight loss, decreased immunity, fatigue and other characteristic symptoms of the oncological process. In the small intestine, a tumor and the accompanying carcinoid syndrome are recorded a little more often than in the lungs. Its signs are very scarce. Often only nonspecific abdominal pain is present. This is due to the small size of the tumor. Sometimes it cannot be detected even during surgery. Often the formation is noticed accidentally during an X-ray examination.