Carcinoid Tumors of the Lungs
What is a lung carcinoid tumor?
A lung carcinoid tumor is a type of cancerous tumor made up of neuroendocrine cells. These cells are found throughout the body, including the lungs. They are similar to endocrine cells because both produce hormones or hormone-like substances. In other ways, they resemble nerve cells because both can secrete neurotransmitters.
Sometimes neuroendocrine cells grow too quickly and form a small tumor known as a carcinoid tumor. Carcinoid tumors may form in other organs of the body besides the lungs. In fact, only about 2 out of 10 carcinoid tumors are found in the lungs.
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’s a greater chance that they will spread (metastasize) beyond the lungs. Another way to classify lung carcinoid tumors is by their location. Central carcinoids are found in the walls of the large airways of the lungs. Peripheral carcinoids form closer to the edges of the lungs in the smaller airways. Both central and peripheral carcinoids usually are typical carcinoids.
How common are carcinoid tumors of the lung?
Lung carcinoid tumors are quite rare, accounting for only 1% to 2% of all lung cancers. There are about 2,000 to 4,500 new cases of lung carcinoid tumors diagnosed in the United States each year. Carcinoid tumors are much more likely to develop in other places in the body, such as the digestive tract, than in the lungs. People who get carcinoid tumors of the lungs are typically younger than people who develop other types of lung cancer.
Symptoms and Causes
What causes lung carcinoid tumors?
The cause of lung carcinoid tumors is still unclear. They don’t seem to be related to smoking, air pollutants or other chemicals. However, there are factors that may put some people at an increased risk. Lung carcinoids are more likely to develop in whites than in people of other races. The tumors 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.
What are the symptoms of lung carcinoid tumors?
About 25% or more of people with lung carcinoid tumors don’t have any symptoms. Often these types of tumors are found when you have diagnostic tests for another illness, such as a chest X-ray for a lung infection.
When symptoms are present, usually there is coughing or 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.
Carcinoid syndrome is a condition related to overproduction of certain hormones by the tumors' neuroendocrine cells. It’s uncommon to have the carcinoid syndrome from a lung carcinoid tumor. Symptoms of carcinoid syndrome may include:
- Facial flushing (warmth) and redness.
- Wheezing, shortness of breath or asthma-like symptoms.
- 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’s important to see your healthcare provider to find out the actual cause of the symptoms.
Diagnosis and Tests
How are lung carcinoid tumors diagnosed?
Your healthcare provider will ask you about your medical history and any symptoms that you have. The provider will listen to your lungs and check your breathing. If the provider thinks that you have a problem with your lungs, they will order more tests. Imaging tests include chest X-rays and computed tomography scans.
Chest X-rays might indicate the presence of a lung carcinoid tumor, except in cases where the tumor is very small or is hidden by other organs in the chest.
Computed tomography scan (CT scan): If chest X-rays aren’t clear, a CT scan might be performed. A CT scan yields images that provide a cross sectional view of the lungs and chest. Unlike regular X-rays, CT scans can find very small lung tumors and pinpoint their exact location. They’re also useful in seeing if the tumor has spread to the liver or other organs.
Depending on the test results, your healthcare provider may order other tests to find out if the tumor is a carcinoid or some other form of lung cancer.
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. There are two major types of biopsies:
- Nonsurgical biopsies are done in a hospital or clinic, but they do not require a surgical incision. Although you will have to be sedated before the procedure, recovery times are short. You will probably be able to leave the hospital a few hours after the biopsy is done. The most common type of nonsurgical biopsy for carcinoid tumors is called a bronchoscopy, where a thin, flexible camera is inserted into the breathing passages allowing a biopsy to be performed under direct vision.
- Surgical biopsies are performed under anesthesia and require a surgical incision to be made in the chest. It requires hospitalization and the recovery time is longer than for nonsurgical biopsies.
Management and Treatment
How are lung carcinoid tumors treated?
The method of treatment will depend on the size of the tumor, its location and your overall health. The two main forms of treatment are surgery and radiation therapy.
Many lung carcinoid tumors can be treated with surgery alone, except in cases where the tumor has spread to other organs. In cases where the carcinoid cannot be completely removed, palliative surgery may be performed to remove most of the tumor or to relieve symptoms.
The main types of surgical treatment are:
- Lobectomy: This type of surgical procedure involves the removal of a portion of the lung called a lobe. It may be performed to remove a peripheral carcinoid tumor (one that is located at the edge of the lungs). One lobe of the lung is removed during a lobectomy. The removal of two lobes is called a bilobectomy. A procedure known as sleeve resection falls into this category. A sleeve resection removes sections of the airway above and below the tumor along with the tumor. The sections of the airway are then reconnected, similar to sewing the sections of a sleeve together after part of it has been cut off.
- Pneumonectomy: This procedure involves removal of the entire lung.
- Sublobar resection: This category includes segmentectomy and wedge resection. Segmentectomy refers to the removal of a part of one lobe of the lung. Wedge resection refers to removing a small, wedge-shaped portion of the lung in cases where the tumor is very small.
- Lymph node dissection: Often, the lymph nodes near the lungs are removed during the above surgeries to determine if the tumor has spread to these nodes and possibly to reduce the risk of the tumor spreading to other parts of the body.
Radiation therapy: This type of treatment uses high-energy radiation to destroy cancer cells. Usually, the patient undergoes a series of radiation treatments over a certain period of time. External-beam radiation therapy is the usual type of radiation therapy to treat carcinoid tumors. Radiation may also be given through tiny pellets or rods that are delivered to the tumor or close to it through a small catheter. This is known as internal radiation or brachytherapy.
A drug called Sandostatin® (octreotide) is sometimes used to treat carcinoid syndrome by controlling hormone output.
Chemotherapy: This may be required in cases in which the tumor has spread from the lungs to other organs. Chemotherapy involves the use of drugs administered via the bloodstream (intravenously) to destroy cancer cells. Chemotherapy might be given in the hospital or in a doctor's office or a clinic. Usually a certain number of treatments are given over time.
For treating metastic cancer, an mTOR inhibitor, everolimus (AFINITOR®), is used ahead of chemotherapy in these cases. Also, peptide radioligand therapy is used for metastatic disease where the treatment is avilable.
Outlook / Prognosis
What is the outlook for patients with lung carcinoid tumors?
The prognosis is in general very good. The average five-year survival rate for people who have been treated for typical carcinoid tumors is 85% to 95%. People who have been treated for atypical lung carcinoids have a five-year survival rate of 50% to 60%. Survival rates tend to be higher for people with lung carcinoids that haven't spread.
It's important to schedule regular follow-up visits with your healthcare team after treatment because carcinoid tumors can come back. That's why you should follow up with your provider for surveillance. Let your doctor know if you begin to experience any unusual symptoms, such as difficulty breathing, unexpected weight loss or pain.
A note from Cleveland Clinic
Lung carcinoid tumors are often found during testing for other conditions. They are rare cancers with treatment options. If you are concerned in any way about wheezing or coughing, check with your healthcare provider. If you have been treated for a lung carcinoid tumor, make sure to keep your scheduled series of follow-up visits with your provider. Remember, the prognosis after treatment is very good.
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