How are lung carcinoid tumors diagnosed?

Certain signs and symptoms might suggest that a person may have a lung carcinoid tumor, but tests are needed to confirm the diagnosis.

Signs and symptoms

About 2 out of 3 people with carcinoid tumors will have signs or symptoms that will lead to the diagnosis of the disease. But because carcinoids tend to grow slowly, they may not cause symptoms for several years in some people, or they may be found by medical tests done for other reasons.

Central carcinoid tumors

These tumors start in the large bronchial tubes leading into the lung. People with these tumors may have a cough, sometimes with bloody sputum, or they may have wheezing symptoms like asthma. Other possible symptoms include shortness of breath and chest pain, especially when taking deep breaths.

Large carcinoids can cause partial or complete blockage of an air passage, leading to a lung infection called post-obstructive pneumonia. Sometimes a doctor may suspect a tumor only after treatment with antibiotics fails to cure the pneumonia.

Peripheral carcinoids

These 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 they interfere with breathing. Usually they are found as a spot on a chest x-ray or CT scan taken for an unrelated problem.

Symptoms caused by hormones from the tumor

Some carcinoid tumors can make hormone-like substances that are released into the bloodstream. Lung carcinoids do this far less often than gastrointestinal carcinoid tumors.

Carcinoid syndrome: Rarely, lung carcinoid tumors release enough hormone-like substances into the bloodstream to cause symptoms. This results in the carcinoid syndrome. Symptoms can include facial flushing (redness and warm feeling), severe diarrhea, wheezing, and fast heartbeat. Many patients find that stress, heavy exercise, and drinking alcohol can bring on these symptoms or make them worse. Over a long time, these hormone-like substances can damage heart valves, causing shortness of breath, weakness, and a heart murmur (an abnormal heart sound).

Cushing syndrome: In rare cases, lung carcinoid tumors may make a hormone called ACTH. This substance causes the adrenal glands to make too much cortisol and other hormones. This can cause weight gain, weakness, high blood sugar (or even diabetes), and increased body and facial hair.

The symptoms and signs above may be caused by lung carcinoid tumors, but they can also be caused by other conditions. Still, if you have any of these problems, it's important to see your doctor right away so the cause can be found and treated, if needed.

Medical history and physical exam

If you have any signs or symptoms that suggest you might have a lung carcinoid 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 provides 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 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

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.

Chest x-ray

A chest x-ray may be the first imaging test a doctor orders if he or she suspects a lung problem. 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

The CT scan is an x-ray test that produces 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 of 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.

You need to lie still on a table while the scan is being done. During the test, the table slides in and out of the scanner, a ring-shaped machine that completely surrounds it. You might feel a bit confined by the ring you have to lie in 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 or metastasis. For this procedure, called a CT-guided needle biopsy, the patient remains on the CT scanning table, while a radiologist 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.

Radionuclide scans

Scans using small amounts of radioactivity and special cameras may be helpful in looking for carcinoid tumors. They can help determine the extent of the tumor, as well as help locate it if doctors aren't sure where it is in the body.

Somatostatin receptor scintigraphy: The most commonly used 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. About 4 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.

I-131 MIBG: This test is used less often. It uses a chemical called MIBG to which radioactive iodine (I-131) is attached. 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): A PET scan is another imaging test that uses low levels of radioactivity to look for tumors. For most diseases, PET scans use a form of radiolabeled glucose (sugar) to find tumors. This type of PET scan is not very useful in finding carcinoid tumors. 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.

Sputum cytology

Even if an imaging test such as a chest x-ray or CT scan finds a mass, it is 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 more likely to help find cancers that start in the major airways of the lung. It may not be as helpful for finding cancers in other parts of the lungs. Sputum cytology is not as good at finding lung carcinoids as it is at finding other types of lung cancers.

Biopsy

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.

Bronchoscopic biopsy

This approach is used to view and sample tumors of large airways, such as central carcinoids. The doctor passes a long, thin, flexible, fiber-optic tube called a bronchoscope down the throat, through the windpipe, and into the lungs to look at the lining of the lung's main airways. You will be sedated for this. If a tumor is found, the doctor can take a small sample 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 surgical incision 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): EBUS uses a special bronchoscope that has a small balloon on the end. This special bronchoscope is inserted like a regular bronchoscope. The balloon gives off sound waves and collects information about the waves that bounce back (like an ultrasound transducer), showing lymph nodes around the trachea (windpipe).

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 minimally invasive approach can be used to biopsy these nodes. Under ultrasound guidance, a needle can be inserted through the wall of the bronchus into these lymph nodes to remove some cells, which are then looked at under the microscope.

Needle biopsies

Tumors that are toward the outside of the lungs (and not near the large airways) are often sampled by needle biopsy. A long, hollow needle is passed through the skin in the chest between the ribs and into the lung. CT scan images are used to guide the needle into the tumor so that a small sample can be removed and looked at under the microscope. This procedure is done without a surgical incision or overnight hospital stay.

A possible complication of this approach is the buildup of air between the lung and the chest wall, which is known as a pneumothorax. This often goes away on its own, but sometimes it can lead to the collapse of part of a lung, causing shortness of breath. If this happens, it can be treated by temporarily placing a suction tube through the skin and into the chest, which will re-expand the lung.

Surgical biopsies

In some cases, neither a bronchoscopic biopsy nor a needle biopsy will 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.

Thoracotomy: For a thoracotomy, the surgeon makes an incision 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 is less invasive than a thoracotomy. It is most often done in the operating room while you are under general anesthesia (in a deep sleep).

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 between the lungs. It is done in an operating room while you are under general anesthesia (in a deep sleep). A small cut is made in the front of the neck above the breastbone (sternum) and a thin, hollow, lighted tube is inserted behind the sternum. Special instruments can be passed through this tube to take tissue samples from the lymph nodes along the windpipe and the major bronchial tube areas.

Blood and urine tests

Because carcinoid tumors can secrete hormone-like chemicals into the blood, the tumor can sometimes be detected by simple blood or urine tests. This is especially true if you have symptoms of the carcinoid syndrome, which is caused by excessive 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 commonly used to look for carcinoids can 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 is an option in treating the cancer. Because surgery will remove part or all of the lung, it's important to know how well the 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 safely be removed.

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.