How are lung carcinoid tumors diagnosed?
Certain signs and symptoms might suggest that a person could have a lung carcinoid tumor, but tests are needed to confirm the diagnosis.
Medical history and physical exam
If you have any signs or symptoms that suggest you might have a lung carcinoid tumor (or another type of lung tumor), your doctor will want to take a complete medical history, including your family history, to learn about your symptoms and possible risk factors.
A physical exam can give your doctor information about your general health, possible signs of lung carcinoid tumor, and other health problems. During your exam, your doctor will pay close attention to your chest and lungs.
If your symptoms or the results of the exam suggest you might have a lung carcinoid tumor (or another type of tumor), more tests will be done. These might include imaging tests, lab tests, and other procedures.
Imaging tests use x-rays, radioactive particles, or other means to create pictures of the inside of your body. Imaging tests may be done for a number of reasons, including to help find a suspicious area that might be cancer, to learn how far cancer may have spread, and to help determine if treatment has been effective.
A chest x-ray is often the first imaging test a doctor orders if a lung problem is suspected. It might be able to show if there is a tumor in the lung. But some carcinoids that are small or are in places where they are covered by other organs in the chest may not show up on a chest x-ray. If your doctor is still suspicious or if something is seen on the chest x-ray, a CT scan may be ordered.
Computed tomography (CT) scan
A CT (or CAT) scan is more likely to show lung tumors than routine chest x-rays. A CT scan can also provide precise information about the size, shape, and position of any lung tumors and can help find enlarged lymph nodes that might contain cancer that has spread from the lung.
The CT scan uses x-rays to produce detailed cross-sectional images of your body. Instead of taking one picture, like a regular x-ray, a CT scanner takes many pictures as it rotates around you while you are lying on a narrow platform. A computer then combines these into images showing slices of the part of your body that is being studied.
Before any pictures are taken, you may be asked to drink 1 to 2 pints of a liquid called oral contrast. This helps outline the intestine so that certain areas are not mistaken for tumors. This is not needed if the CT scan is only looking at the chest and lungs. You may also receive an IV (intravenous) line through which a different kind of contrast dye (IV contrast) is injected. This helps better outline structures in your body. The injection can cause some flushing (redness and warm feeling). Some people are allergic and get hives or, rarely, more serious reactions like trouble breathing and low blood pressure. Be sure to tell the doctor if you have any allergies or have ever had a reaction to any contrast material used for x-rays.
A CT scanner has been described as a large donut, with a narrow table that slides in and out of the middle opening. You will need to lie still on the table while the scan is being done. CT scans take longer than regular x-rays, and you might feel a bit confined by the ring while the pictures are being taken.
CT scans can have several uses:
- CT scans of the chest can spot very small lung tumors and help determine the exact location and extent of the tumors.
- CT scans can be helpful in staging a cancer (determining the extent of its spread). For example, CT scans of the abdomen can show if the cancer has spread to the liver or other organs. This can help to determine if surgery is a good treatment option.
- CT scans can also be used to guide a biopsy needle precisely into a suspected tumor. For this procedure, called a CT-guided needle biopsy, you stay on the CT scanning table while the doctor advances a biopsy needle through the skin and toward the mass. CT scans are repeated until the needle is within the mass. A biopsy sample is then removed and looked at under a microscope.
- CT scans can be done during or after treatment to see how effective the treatment has been.
Scans using small amounts of radioactivity and special cameras may be helpful in looking for carcinoid tumors. They can help find tumors or look for areas of cancer spread if doctors aren’t sure where they are in the body.
Somatostatin receptor scintigraphy: The most common scan is somatostatin receptor scintigraphy (SRS), also known as the OctreoScan. It uses a drug called octreotide bound to radioactive indium-111. Octreotide is a hormone-like substance that attaches to carcinoid cells. A small amount is injected into a vein. It travels through the blood and is attracted to carcinoid tumors. A few hours after the injection, a special camera can be used to show where the radioactivity has collected in the body. More scans may be done in the following few days as well. Along with showing where tumors are, this test can help tell whether treatment with certain drugs such as octreotide and lanreotide is likely to be helpful.
I-131 MIBG: This test is used less often. It uses a chemical called MIBG attached to radioactive iodine (I-131). This substance is injected into a vein, and the body is scanned several hours or days later with a special camera to look for areas that picked up the radioactivity. These would most likely be carcinoid tumors, but other kinds of neuroendocrine tumors will also pick up this chemical.
Positron emission tomography (PET): For most types of cancer, PET scans use a form of radioactive glucose (sugar) to find tumors. But this type of PET scan is not very useful in finding carcinoid tumors. Instead, PET scanning for carcinoid tumors usually uses a radioactive form of 5-hydroxytryptophan, a chemical that is taken up and used by carcinoid cells. A special camera can detect the radioactivity. The usefulness of this test for lung carcinoid tumors is still being studied. This special type of PET scan is not available in every hospital.
Even if an imaging test such as a chest x-ray or CT scan shows a mass, it’s often hard for doctors to tell if the mass is a carcinoid tumor, another type of lung cancer, or an area of infection. Tests may be needed to get a sample of the abnormal cells to be looked at under a microscope.
One way to do this is called sputum cytology. A sample of sputum (mucus you cough up from the lungs) is looked at under a microscope to see if it contains cancer cells. The best way to do this is to get samples taken early in the morning, 3 days in a row.
This test is not as good at finding lung carcinoids as it is at finding other types of lung cancers.
In many cases, the only way to know for sure if a person has some type of lung cancer is to remove cells from the tumor and look at them under a microscope. This procedure is called a biopsy. There are several ways to take a sample from a lung tumor.
This approach is used to view and sample tumors in large airways. The doctor passes a long, thin, flexible, fiber-optic tube called a bronchoscope down the throat and through the windpipe and bronchi to look at the lining of the lung’s main airways. The mouth and throat are sprayed first with a numbing medicine. You may also be given medicine through an intravenous (IV) line to make you feel relaxed.
If a tumor is found, the doctor can take biopsies (small samples of the tumor) through the tube. The doctor can also sample cells from the lining of the airways by wiping a tiny brush over the surface of the tumor (bronchial brushing) or by rinsing the airways with sterile saltwater and then collecting it (bronchial washing). Brushing and washing samples are sometimes helpful additions to the bronchial biopsy, but they are not as helpful in diagnosing carcinoids as they are with other lung cancers.
An advantage of this type of biopsy is that no surgery or hospital stay is needed, and you are ready to return home within hours. A disadvantage is that this type of biopsy may not always be able to remove enough of a sample to be certain that a tumor is a carcinoid. But with recent advances in the lab testing of lung tumors, doctors can usually make an accurate diagnosis even with very small samples.
Bleeding from a carcinoid tumor after a biopsy is rare but it can be a serious problem. If bleeding becomes a problem, doctors can inject drugs through the bronchoscope into the tumor to narrow its blood vessels, or they can seal off the bleeding vessels with a laser aimed through the bronchoscope.
Endobronchial ultrasonography (EBUS)
If a CT scan shows lymph nodes are enlarged on either side of the trachea or in the area just below where the trachea divides, this test can be used to biopsy these nodes to see if they contain cancer.
Ultrasound is a type of imaging test that uses sound waves to create pictures of the inside of your body. For this test, a small, microphone-like instrument called a transducer gives off sound waves and picks up the echoes as they bounce off body tissues. The echoes are converted by a computer into a black and white image on a computer screen.
For endobronchial ultrasound, a bronchoscope is fitted with an ultrasound transducer at its tip and is passed down into the windpipe. This is done with numbing medicine (local anesthesia) and light sedation.
The transducer can be pointed in different directions to look at lymph nodes and other structures in the mediastinum (the area between the lungs). A hollow needle can be passed through the bronchoscope to get biopsy samples of enlarged lymph nodes or other abnormal areas. The samples are then sent to a lab to be looked at under a microscope.
Doctors can often use a hollow needle to get a small sample from a suspicious area (mass). An advantage of needle biopsies is that they don’t require a surgical incision, but in some cases they might not provide enough of a sample to make a diagnosis. There are two types of needle biopsies, based on the type of needle used:
- In a fine needle aspiration (FNA) biopsy, the doctor uses a syringe with a very thin, hollow needle (thinner than the ones used for blood tests) to withdraw (aspirate) cells and small fragments of tissue.
- In a core biopsy, a larger needle is used to remove one or more small cylinders (cores) of tissue. Core biopsies provide a larger sample than FNA biopsies.
If the suspected tumor is in the outer part of the lungs, either kind of biopsy needle can be inserted through the skin on the chest wall. This is called a transthoracic needle biopsy. The area where the needle is to be inserted may be numbed with local anesthesia first. The doctor then guides the needle into the area while looking at the lungs with either fluoroscopy (which is like an x-ray, but the image is shown on a screen rather than on film) or CT scans. Unlike fluoroscopy, CT doesn’t give a constant picture, so the needle is inserted toward the mass, a CT image is taken, and the direction of the needle is guided based on the image. This is repeated a few times until the needle is within the mass.
A possible complication of this procedure is that air may leak out of the lung at the biopsy site and into the space between the lung and the chest wall. This can cause part of the lung to collapse and could cause trouble breathing. This complication, called a pneumothorax, often gets better without any treatment. If not, it’s treated by putting a small tube into the chest space and sucking out the air over a day or two, after which it usually heals on its own.
An FNA biopsy may also be done to check for cancer in the lymph nodes between the lungs. This can be done in two ways:
- Transtracheal FNA or transbronchial FNA is done by passing the needle through the wall of the trachea (windpipe) or bronchi (the large airways leading into the lungs) during bronchoscopy or EBUS (described above).
- In some cases an FNA biopsy is done during endoscopic esophageal ultrasound (which is similar to EBUS, except that the scope is passed down the esophagus instead of the windpipe) by passing the needle through the wall of the esophagus.
In some cases, the types of biopsies above can’t remove enough tissue to identify the type of tumor, and your doctor may need to do surgery to get a biopsy sample. Different types of operations may be used. They are most often done in the operating room while you are under general anesthesia (in a deep sleep).
Thoracotomy: For a thoracotomy, the surgeon makes an incision (cut) in the chest wall between the ribs to get to the lungs and to the space between the lungs and the chest wall. In some cases if the doctor strongly suspects a carcinoid or some other type of lung cancer, they may do a thoracotomy and remove the entire tumor without first doing a biopsy.
Thoracoscopy: This procedure is also used to look at the space between the lungs and the chest wall, but it does not require a long incision like a thoracotomy. The doctor inserts a thin, lighted scope with a small video camera on the end through a small cut made in the chest wall to look at the outside of the lungs and the space between the lungs and the chest wall. (Sometimes more than one cut is made.) Using this scope, the doctor can see potential areas of cancer and remove small pieces of tissue to look at under the microscope. Thoracoscopy can also be used to sample lymph nodes and fluid and find out whether a tumor is growing into nearby tissues or organs.
Mediastinoscopy: This procedure may be done if imaging tests such as a CT scan suggest that the cancer may have spread to the lymph nodes in the mediastinum (the space between the lungs). A small cut is made in the front of the neck and a thin, hollow, lighted tube is inserted behind the sternum (breast bone) and in front of the windpipe to look at the area. Instruments can be passed through this tube to take tissue samples from the lymph nodes along the windpipe and the bronchi.
Blood and urine tests
Because carcinoid tumors can secrete hormone-like chemicals into the blood, these tumors can sometimes be found with blood or urine tests. This is especially true if you have symptoms of the carcinoid syndrome, which is caused by excess levels of these substances in the blood.
Serotonin is a substance made by some carcinoid tumors, and probably causes some of the symptoms. It is broken down by the body into 5-hydroxyindoleacetic acid (5-HIAA), which is released into the urine. A common test to look for carcinoid syndrome measures the levels of 5-HIAA in a urine sample collected over 24 hours. Measuring the serotonin levels in the blood or urine may also give useful information. These tests can help diagnose some carcinoid tumors, but they are not always accurate. Some other medical conditions, as well as foods and medicines, can affect the results, and some carcinoid tumors may not release enough of these substances to give a positive test result.
Other tests used to look for carcinoids include blood tests for chromogranin A (CgA), neuron-specific enolase (NSE), cortisol, and substance P. Depending on where the tumor might be located and on the patient’s symptoms, doctors may do other blood tests as well.
These tests are less likely to be helpful with lung carcinoid tumors than with carcinoid tumors that start elsewhere in the body.
Pulmonary function tests
If a lung carcinoid is found, pulmonary function tests (PFTs) are often done to see how well your lungs are working. This is especially important if surgery might be used to treat the cancer. Because surgery will remove part or all of the lung, it’s important to know how well your lungs are working beforehand. These tests can give the surgeon an idea of whether surgery is a good option, and if so, how much lung can be removed safely.
There are a few different types of PFTs, but they all basically have you breathe in and out through a tube that is connected to a machine that measures airflow.
Last Medical Review: 11/13/2013
Last Revised: 11/13/2013