Signs and Symptoms of Lung Neuroendocrine Tumors

Most lung neuroendocrine tumors (NETs) grow slowly. If they do cause symptoms, they tend to be vague and other more common possible causes are likely to be explored first. This can delay a diagnosis, sometimes for several years.

Symptoms by tumor location

Lung NETs in different locations within the lung may cause distinct symptoms.

Central lung NET

Most lung NETs start in the large bronchial tubes leading into the lung. Symptoms can include:

• Cough, sometimes bloody
• Wheezing
• Shortness of breath
• Chest pain, especially when taking deep breaths
• Recurrent pneumonia (infection of the lung)

Large tumors can cause partial or complete blockage of an air passage, which can lead to pneumonia. Sometimes a doctor may suspect a tumor only after pneumonia doesn’t respond to treatment with antibiotics.

Peripheral lung NET

Some tumors start in the smaller airways toward the outer edges of the lungs. They rarely cause any symptoms unless there are so many of them that they cause trouble breathing. Usually, they are found as a spot on a chest x-ray or CT scan that is done for an unrelated problem.

Signs and symptoms from hormones made by neuroendocrine tumors

Some NETs release hormones into the bloodstream. This can cause different symptoms depending on the hormones released. Lung NETs do this far less often than gastrointestinal NETs.

Carcinoid syndrome

About 1 in 10 NETs release enough hormone-like substances into the bloodstream to cause carcinoid syndrome symptoms. These include:

• Facial flushing (redness and warmth)
• Severe diarrhea
• Wheezing
• Fast heartbeat

Many people find that factors such as stress, heavy exercise, and drinking alcohol trigger these symptoms. Over time, these hormone-like substances can damage heart valves, causing shortness of breath, weakness, and a heart murmur (an abnormal heart sound).

Most cases of carcinoid syndrome occur only after the cancer has already spread to other parts of the body. NETs that have spread to the liver are most likely to cause carcinoid syndrome.

Cushing syndrome

Some NETs produce ACTH (adrenocorticotropic hormone), a substance that causes the adrenal glands to make too much of the steroid cortisol. This can cause Cushing syndrome, with symptoms of:

• Weight gain
• Muscle weakness
• High blood sugar or diabetes
• High blood pressure
• Increased body and facial hair
• A bulge of fat on the back of the neck
• Skin changes like stretch marks (striae)