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What is a lung carcinoid tumor?

A lung carcinoid tumor is a type of growth that is composed of neuroendocrine cells. Under the microscope, these cells are similar to endocrine cells in the body that produce hormones. Carcinoid tumors may form in other organs of the body besides the lungs. In fact, only about 3 out of 10 carcinoid tumors are found in the lungs. Lung carcinoid tumors tend to grow slowly.

There are two types of lung carcinoid tumors: typical and atypical.

  • Typical carcinoids account for about 9 out of 10 lung carcinoids. They grow slowly and rarely spread beyond the lungs.
  • Atypical carcinoids are much rarer than typical lung carcinoids. They tend to grow faster than typical carcinoids. There is a greater chance that they will spread (metastasize) beyond the lungs. When viewed under a microscope, an atypical carcinoid has more cells undergoing the process of cell division (growth) than a typical carcinoid tumor does.

Another way to classify lung carcinoid tumors is by their location. Central carcinoids are found in the large airways (breathing tubes) that connect the lungs to the center of the chest. Peripheral carcinoids form closer to the edges of the lungs in the narrower air passages.

What causes lung carcinoid tumors?

The cause of lung carcinoid tumors is unknown. They have not been demonstrated to be related to smoking, air pollutants, or other chemicals. However, there are factors that may put some people at an increased risk for developing one. Lung carcinoids are more likely to develop in whites than in people of other races and tend to be present in more women than men. People with a rare inherited disorder called multiple endocrine neoplasia type 1 (MEN1) are at somewhat higher risk for lung carcinoids.

How common are carcinoid tumors of the lung?

Lung carcinoid tumors are quite rare. There are about 4,500 new cases of lung carcinoid tumors diagnosed in the United States each year compared to almost 200,000 lung cancers. Carcinoid tumors are much more likely to develop in the digestive tract than in the lungs.

What are the symptoms of lung carcinoid tumors?

Many patients with lung carcinoid tumors do not have any symptoms. Often these types of tumors are found when a patient undergoes a test for another illness, such as a chest X-ray for a lung infection.

When symptoms are present, usually these symptoms include cough and wheezing. The cough might produce blood in the phlegm or sputum. If the tumor is large enough to block an air passage, a person might develop an infection called post-obstructive pneumonia which is caused by the backup of infected sputum behind the tumor.

Carcinoid syndrome is a condition related to overproduction of certain hormones by the tumors’ neuroendocrine cells. It is uncommon to have the carcinoid syndrome from a lung carcinoid tumor. Symptoms of carcinoid syndrome may include:

  • Facial flushing (warmth) and redness
  • Wheezing or asthma-like symptoms
  • Shortness of breath
  • Weakness
  • High blood pressure
  • Weight gain
  • Increased amount of body and facial hair (hirsutism)

The symptoms of carcinoid syndrome may be caused by other disorders. It is important to see your doctor to find out the actual cause of the symptoms.

How is a lung carcinoid tumor diagnosed?

Your doctor will ask you about your medical history and any symptoms that you have. He or she will listen to your lungs and check your breathing. If your doctor suspects that there is a problem with your lungs, he or she will order more tests including:

Chest X-rays – a routine X ray that might indicate the presence of a lung carcinoid tumor.

Computed tomography scan (CT scan) — A CT scan yields images that provide a cross sectional view of the lungs and chest. Unlike regular X-rays, CT scans can detect very small lung tumors and pinpoint their exact location and aid in operative planning.

Depending on the test results, your doctor may order other tests to find out if the tumor is a carcinoid or some other form of lung growth.

Blood and urine tests—Abnormal levels of hormones or other substances linked with carcinoid tumors might be present in the blood or urine. Blood tests to measure the levels of serotonin or chromogranin-A might indicate the presence of a typical carcinoid. Urine tests can measure the level of 5-HIAA, a metabolite of serotonin. These tests are most helpful in the small percentage of people with lung carcinoid tumors who present with the carcinoid syndrome. In most others these tests will be normal.

Biopsy–A biopsy is a procedure in which a small sample of the tumor or growth is removed so that the cells can be examined under a microscope. Usually these can be reached and biopsied with a bronchoscope (small telescope inserted into the windpipe).

How are lung carcinoids treated?

The method of treatment depends on the size of the tumor, its location, and a patient’s overall health. Surgery is the mainstay of treatment. Your surgeon will guide you in this decision making.

The main types of surgical treatment are

  • Sleeve resection— An operation that involves cutting a section of the airway (breathing tube) above and below the tumor and removing this section along with the tumor itself. The sections of the airway are then reconnected. Lung tissue may or may not have to be removed. This is a complex procedure that should be performed by a thoracic surgeon with experience in this type of airway reconstruction. All thoracic surgeons in the Center for Thoracic Surgery have experience with sleeve resection.
  • Wedge resection—In cases where the tumor is very small, a procedure may be performed to remove a small, wedge-shaped portion of the lung using minimally invasive surgery.
  • Lobectomy—This is the primary type of surgery performed for carcinoid tumor. This type of surgical procedure involves the removal of a portion of the lung called a lobe. This can typically be performed using minimally invasive techniques such as VATS (video assisted thoracic surgery) or robotically.
  • Pneumonectomy—This procedure involves removal of the entire lung. It is rarely required for a carcinoid tumor.
  • Lymph node dissection—The lymph nodes (drainage basins) of the lungs and the tumor are always removed during surgery for carcinoid tumors to reduce the risk of the tumor spreading to other parts of the body.
  • What is the outlook for patients with lung carcinoid tumors?

    Prognosis for carcinoids is excellent. Typical carcinoids have better prognosis than atypical carcinoids. Survival rates are higher for people with lung carcinoids that are localized as opposed to tumors that have spread.

    Your doctor will schedule regular follow-up visits for you after surgery with CAT scan imaging to be certain that the tumor does not recur (come back).