Tests for Small Cell Lung Cancer

Screening can find some lung cancers, but most lung cancers are found because they are causing problems. If you have possible signs or symptoms of lung cancer, see your doctor, who will examine you and may order some tests. The actual diagnosis of lung cancer is made after looking at a sample of your lung cells under a microscope.

Medical history and physical exam

Your doctor will ask about your medical history to learn about your symptoms and possible risk factors. You will also be examined for signs of lung cancer or other health problems.

If the results of your history and physical exam suggest you might have lung cancer, you will have tests to look for it. These could include imaging tests and/or biopsies of lung tissue.

Imaging tests to look for lung cancer

Imaging tests use x-rays, magnetic fields, sound waves, or radioactive substances to create pictures of the inside of your body. Imaging tests might be done for a number of reasons both before and after a diagnosis of lung cancer, including:

  • To look at suspicious areas that might be cancer
  • To learn if and how far cancer has spread
  • To help determine if treatment is working
  • To look for possible signs of cancer coming back after treatment

Chest x-ray

This is often the first test your doctor will do to look for any abnormal areas in the lungs. Plain x-rays of your chest can be done at imaging centers, hospitals, and even in some doctors’ offices. If the x-ray result is normal, you probably don’t have lung cancer (although some lung cancers may not show up on an x-ray). If something suspicious is seen, your doctor will likely order more tests.

Computed tomography (CT) scan

A CT scan combines many x-rays to make detailed cross-sectional images of your body.

A CT scan is more likely to show lung tumors than a routine chest x-ray. It can also show 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. Most people with small cell lung cancer (SCLC) will get a CT of the chest and abdomen to look at the lungs and lymph nodes, and to look for abnormal areas in the adrenal glands, liver, and other organs that might be from the spread of lung cancer. Some people will get a CT of the brain to look for cancer spread, but an MRI is more likely to be used when looking at the brain.

CT guided needle biopsy: If a suspected area of cancer is deep within your body, a CT scan can be used to guide a biopsy needle precisely into the suspected area.

Magnetic resonance imaging (MRI) scan

Like CT scans, MRI scans show detailed images of soft tissues in the body. But MRI scans use radio waves and strong magnets instead of x-rays.

Most patients with SCLC will have an MRI scan of the brain to look for possible cancer spread, although a CT scan may be used instead. MRI may also be used to look for possible spread to the spinal cord if the patients have certain symptoms.

Positron emission tomography (PET) scan

For a PET scan, you are injected with a slightly radioactive form of sugar, which collects mainly in cancer cells. A special camera is then used to create a picture of areas of radioactivity in the body.

A PET scan can be a very important test if you appear to have early stage (or limited) SCLC. Your doctor can use this test to see if the cancer has spread to lymph nodes or other organs, which can help determine your treatment options. A PET scan can also give a better idea whether an abnormal area on a chest x-ray or CT scan might be cancer. PET scans are also useful if your doctor thinks the cancer may have spread but doesn't know where.

PET/CT scan: Some machines can do both a PET scan and a CT scan at the same time. This lets the doctor compare areas of higher radioactivity on the PET scan with the more detailed appearance of that area on the CT scan. For people with SCLC, PET/CT scans are used more often than PET scans alone.

Bone scan

A bone scan can help show if a cancer has spread to the bones. This test is done mainly when there is reason to think the cancer may have spread to the bones (because of symptoms such as bone pain) and other test results aren’t clear.

For this test, you are injected with a slightly radioactive chemical that collects mainly in abnormal areas of bone. A special camera is then used to create a picture of areas of radioactivity in the body..

PET scans can also usually show if the cancer has spread to the bones, so you usually won’t need a bone scan if a PET scan has already been done.

Tests to diagnose lung cancer

Symptoms and the results of imaging tests might suggest that a person has lung cancer, but the actual diagnosis is made by looking at cells from your lung with a microscope.

The cells can be taken from lung secretions (sputum or phlegm), fluid removed from the area around the lung (thoracentesis), or from a suspicious area (biopsy). The choice of which test(s) to use depends on the situation.

Sputum cytology

For this test, a sample of sputum (mucus you cough up from the lungs) is looked at under a microscope to see if it has cancer cells. The best way to do this is to get early morning samples from you 3 days in a row. This test is more likely to help find cancers that start in the major airways of the lung, such as most small cell lung cancers and squamous cell lung cancers. It may not be as helpful for finding other types of lung cancer.


If fluid has built up around your lungs (called a pleural effusion), doctors can use thoracentesis to relieve symptoms and to see if it is caused by cancer spreading to the lining of the lungs (pleura). The buildup might also be caused by other conditions, such as heart failure or an infection.

For this procedure, the skin is numbed and a hollow needle is inserted between the ribs to drain the fluid. (In a similar test called pericardiocentesis, fluid is removed from within the sac around the heart.) A microscope is used to check the fluid for cancer cells. Chemical tests of the fluid are also sometimes useful in telling a malignant (cancerous) pleural effusion from one that is not.

If a malignant pleural effusion has been diagnosed, thoracentesis may be repeated to remove more fluid. Fluid buildup can keep the lungs from filling with air, so thoracentesis can help a person breathe better.

Needle biopsy

Doctors can often use a hollow needle to get a small sample from a suspicious area (mass).

  • In a fine needle aspiration (FNA) biopsy, the doctor uses a syringe with a very thin, hollow needle to withdraw (aspirate) cells and small fragments of tissue.
  • In a core biopsy, a larger needle is used to remove one or more small cores of tissue. Samples from core biopsies are larger than FNA biopsies, so they are often preferred.

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.

Transthoracic needle biopsy: If the suspected tumor is in the outer part of the lungs, the biopsy needle can be inserted through the skin on the chest wall. 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 is called a pneumothorax. It can cause part of the lung to collapse and could cause trouble breathing. If the air leak is small, it often gets better without any treatment. Larger air leaks are 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.

Other approaches to needle biopsies: An FNA biopsy may also be done to check for cancer in the lymph nodes between the lungs:

  • 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 endobronchial ultrasound (described below).
  • Some patients have an FNA biopsy done during endoscopic esophageal ultrasound (described below) by passing the needle through the wall of the esophagus.


Bronchoscopy can help the doctor find some tumors or blockages in the larger airways of the lungs. It may be used to find a lung tumor or to take a sample of a tumor to see if it is cancer.

For this exam, a lighted, flexible fiber-optic tube (called a bronchoscope) is passed through the mouth or nose and down into the windpipe and bronchi. 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.

Small instruments can be passed down the bronchoscope to take biopsy samples. The doctor can also sample cells that line the airways by using a small brush (bronchial brushing) or by rinsing the airways with sterile saltwater (bronchial washing). These tissue and cell samples are then looked at under a microscope.

Tests to find lung cancer spread

If lung cancer has been found, it’s often important to know if it has spread to the lymph nodes in the space between the lungs (mediastinum) or other nearby areas. This can affect a person’s treatment options.

Several types of tests might be done to look for cancer spread if surgery could be an option for treatment, but this is not often the case for small cell lung cancer. These tests are used more often for non-small cell lung cancer.

Endobronchial ultrasound

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 an 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). If suspicious areas such as enlarged lymph nodes are seen on the ultrasound, a hollow needle can be passed through the bronchoscope to get biopsy samples of them. The samples are then sent to a lab to be looked at with a microscope.

Endoscopic esophageal ultrasound

This test is like endobronchial ultrasound, except the doctor passes an endoscope (a lighted, flexible scope) down the throat and into the esophagus (the tube connecting the throat to the stomach). This is done with numbing medicine (local anesthesia) and light sedation.

The esophagus is just behind the windpipe and is close to some lymph nodes inside the chest to which lung cancer may spread. As with endobronchial ultrasound, the transducer can be pointed in different directions to look at lymph nodes and other structures inside the chest that might contain lung cancer. If enlarged lymph nodes are seen on the ultrasound, a hollow needle can be passed through the endoscope to get biopsy samples of them. The samples are then sent to a lab to be looked at under a microscope.

Mediastinoscopy and mediastinotomy

These procedures may be done to look more directly at and get samples from the structures in the mediastinum (the area between the lungs). They are done in an operating room by a surgeon while you are under general anesthesia (in a deep sleep). The main difference between the two is in the location and size of the incision.

Mediastinoscopy: 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 major bronchial tube areas. Looking at the samples under a microscope can show if they contain cancer cells.

Mediastinotomy: The surgeon makes a slightly larger incision (usually about 2 inches long) between the second and third ribs next to the breast bone. This lets the surgeon reach some lymph nodes that cannot be reached by mediastinoscopy.


This procedure can be done to find out if cancer has spread to the spaces between the lungs and the chest wall, or to the linings of these spaces (called pleura). It can also be used to sample tumors on the outer parts of the lungs as well as nearby lymph nodes and fluid, and to assess whether a tumor is growing into nearby tissues or organs. This procedure is not often done just to diagnose lung cancer, unless other tests such as needle biopsies are unable to get enough samples for the diagnosis.

Thoracoscopy is done in an operating room while you are under general anesthesia (in a deep sleep). A small cut (incision) is made in the side of the chest wall. (Sometimes more than one cut is made.) The doctor then puts a thin, lighted tube with a small video camera on the end through the incision to view the space between the lungs and the chest wall. Using this, the doctor can see possible cancer deposits on the lining of the lung or chest wall and remove small pieces of the tissue to be looked at under the microscope. (When certain areas can’t be reached with thoracoscopy, the surgeon may need to make a larger incision in the chest wall, known as a thoracotomy.)

Thoracoscopy can also be used as part of the treatment to remove part of a lung in some early-stage lung cancers. This type of operation, known as video-assisted thoracic surgery (VATS), is described in more detail in Surgery for Small Cell Lung Cancer.

Bone marrow aspiration and biopsy

These tests look for spread of the cancer into the bone marrow. Bone marrow is the soft, inner part of certain bones where new blood cells are made.

The two tests are usually done at the same time. The samples are most often taken from the back of the pelvic (hip) bone.

In bone marrow aspiration, you lie on a table (either on your side or on your belly). The skin over the hip is cleaned. Then the skin and the surface of the bone are numbed with local anesthetic, which may cause a brief stinging or burning sensation. A thin, hollow needle is then inserted into the bone, and a syringe is used to suck out a small amount of liquid bone marrow. Even with the anesthetic, most people still have some brief pain when the marrow is removed.

A bone marrow biopsy is usually done just after the aspiration. A small piece of bone and marrow is removed with a slightly larger needle that is pushed down into the bone. The biopsy will likely also cause some brief pain.

Bone marrow aspiration and biopsy are sometimes done in patients thought to have early (limited) stage SCLC but who have blood test results suggesting the cancer might have reached the bone marrow. In recent years, PET scans have been used more often for staging, so these tests are now rarely done for SCLC.

Lab tests of biopsy and other samples

Samples that have been collected during biopsies or other tests are sent to a pathology lab. A pathologist, a doctor who uses lab tests to diagnose diseases such as cancer, will look at the samples under a microscope and may do other special tests to help better classify the cancer. (Cancers from other organs can spread to the lungs. It’s very important to find out where the cancer started, because treatment is different depending on the type of cancer.)

The results of these tests are described in a pathology report, which is usually available within about a week. If you have any questions about your pathology results or any diagnostic tests, talk to your doctor..

For more information on understanding your pathology report, see Lung Pathology.

Blood tests

Blood tests are not used to diagnose lung cancer, but they can help to get a sense of a person’s overall health. For example, they can be used to help tell if a person is healthy enough to have surgery.

A complete blood count (CBC) determines whether your blood has normal numbers of different types of blood cells. For example, it can show if you are anemic (have a low number of red blood cells), if you could have trouble with bleeding (due to a low number of blood platelets), or if you are at increased risk for infections (due to a low number of white blood cells). This test will be repeated regularly if you are treated with chemotherapy, because these drugs can affect blood-forming cells of the bone marrow.

Blood chemistry tests can help spot abnormalities in some of your organs, such as the liver or kidneys. For example, if cancer has spread to the bones, it may cause higher than normal levels of calcium and alkaline phosphatase.

Lung function tests

Lung (or pulmonary) function tests (PFTs) may be done after lung cancer is diagnosed to see how well your lungs are working. They are generally only needed if surgery might be an option in treating the cancer, which is rare in small cell lung cancer. Surgery to remove lung cancer requires removing part or all of a lung, so it’s important to know how well the lungs are working beforehand.

There are 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.

The American Cancer Society medical and editorial content team

Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

Last Medical Review: February 22, 2016 Last Revised: May 16, 2016

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