Coming to a diagnosis of lung cancer usually starts with a visit to your family doctor. Your doctor may ask you about any unusual symptoms you might have and have a physical exam. Using this information, your doctor may then refer you to a specialist or order tests to check for lung cancer or other health problems.  

The following tests are usually used to rule out or diagnose lung cancer and many of these same tests are used to find out the stage of cancer (how far the cancer has spread). Your doctor may also order other tests to check your general health and to help plan your treatment.

Medical History and Physical Exam

During a medical history, your doctor will ask you questions about yourself to learn about any unusual symptoms that might be related to lung cancer as well as any possible risk factors for lung cancer.  

During a physical exam your doctor will examine you to look for signs of lung cancer or other health problems.

Imaging Tests to Look for Lung Cancer

Imaging tests are used to create pictures of the inside of your body and 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 how far cancer might have spread,
• to help determine if treatment is working, and
• to look for possible signs of cancer coming back after treatment.

Chest X-ray

A chest x-ray is most often one of the first tests your doctor will order to look for any abnormal areas in the lungs.  

Computed Tomography (CT) Scan

A CT scan uses x-rays to make detailed cross-sectional images of your body. Instead of taking 1 or 2 pictures, like a regular x-ray, a CT scanner takes many images and a computer then combines them to show a slice of the part of your body being studied. A CT scan is more likely to show lung tumors than routine chest x-rays and can also show the size, shape, and position of any lung tumors.  

Positron Emission Tomography (PET) Scan  

During a PET scan, a slightly radioactive form of sugar (known as FDG) is injected into the blood and collects mainly in cancer cells.

Magnetic Resonance Imaging (MRI) Scan

Like CT scans, an MRI shows detailed images of soft tissues in the body. An MRI uses radio waves and strong magnets instead of x-rays.  MRI scans are most often used to look for possible spread of lung cancer to the brain or spinal cord.

Bone Scan  

During a bone scan, a small amount of low-level radioactive material is injected into the blood and collects mainly in abnormal areas of bone. A bone scan can help show if a cancer has spread to the bones, however, this test isn’t needed very often because PET scans can usually show if cancer has spread to the bones.

Tests to Diagnose Lung Cancer

Symptoms and the results of certain tests may strongly suggest that a person has lung cancer, but the actual diagnosis is made by looking at lung cells in the lab.  

The cells can be taken from lung secretions, i.e., sputum cytology (mucus you cough up from the lungs), from fluid removed from the area around the lung (thoracentesis), or from a suspicious area using a needle or surgery (biopsy).  

Sputum Cytology  

For sputum cytology, a sample of sputum (mucus you cough up from the lungs) is looked at in the lab to see if it has cancer cells.  

This test is more likely to help find cancers that start in the major airways of the lung, such as squamous cell lung cancers. It might not be as helpful for finding other types of lung cancer. If your doctor suspects lung cancer, further testing will be done even if no cancer cells are found in the sputum.  

Thoracentesis

If fluid has collected around the lungs (called a pleural effusion), doctors can remove some of the fluid to find out 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.

During a thoracentesis, the skin is numbed and a hollow needle is inserted between the ribs to drain the fluid. The fluid is checked in the lab for cancer cells. Other 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 and is causing trouble breathing, a thoracentesis may be repeated to remove more fluid which may help a person breathe better.  

Biopsy

During a needle biopsy, doctors 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. The drawback is that they remove only a small amount of tissue and in some cases, the amount of tissue removed might not be enough to both make a diagnosis and to perform more tests on the cancer cells that can help doctors choose anticancer drugs.

During a surgical biopsy a surgeon takes a sample of the lung tissue by making small cuts in your chest. A pathologist then looks at the cells through a microscope to find out exactly what the abnormality is. This procedure is done under general anesthetic. So you will be asleep and won’t feel anything.