How Is Lung Cancer Diagnosed?

Your healthcare provider may use a combination of physical, blood, imaging, laboratory, and lung function tests to make a lung cancer diagnosis.

Lung cancer is a disease that occurs when cells in the lungs grow out of control and become cancerous. As the condition progresses, the cancer cells can spread to the lymph nodes, brain, and other organs in the body. If you think you may be at risk for developing lung cancer or are experiencing a change in symptoms, it is a good idea to get tested because the disease can spread quickly.  

Your healthcare provider may use several diagnostic measures including physical, blood, imaging, lab, and lung function exams to test you for lung cancer. These tests can help your provider understand your symptoms, the type of cancer you have, and the severity of your condition.

During your diagnostic process, your healthcare provider may consult with a care team made up of a pulmonologist (a doctor who treats lung diseases) and an oncologist (a doctor who treats cancer) to rule out other conditions and provide you with an official diagnosis. Getting tested for lung cancer can be scary. But receiving an early diagnosis can help you get started on treatment sooner. 

Types of Lung Cancer

There are two types of lung cancer: small-cell lung cancer (SCLC) and non-small-cell lung cancer (NSCLC). Your healthcare provider can determine which type you have through testing.

doctor showing elderly couple an x-ray of lungs

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Medical History and Physical Exam

Your healthcare provider will start your appointment by learning about your medical history and performing a physical exam. This first step helps them understand your symptoms and look for potential signs of cancer. 

During your medical history exam, your provider may ask:

  • Do you have a worsening cough?
  • Have you had trouble breathing?
  • Are you coughing up blood or losing weight without trying?
  • What other symptoms do you have?
  • How long have you been experiencing symptoms?
  • Does anyone in your family have lung cancer?
  • Do you currently smoke or have a personal history of tobacco use?
  • Have you had any recent respiratory (lung-related) infections? 

It is also common for your healthcare provider to ask about your lifestyle habits, like diet and exercise. Because exposure to toxins can also increase your risk of developing lung cancer, they may want to learn about your occupation and place of work—because some workplaces can have elevated levels of radon, asbestos, or secondhand smoke in the air. 

Your healthcare provider will perform a routine physical exam, which will likely include:

  • Measuring your vital signs (e.g., temperature, heart rate, blood pressure)
  • Taking your temperature
  • Checking your chest, stomach, and extremities (hands and feet) for pain, weakness, or swelling 

Learning about your medical history and performing a physical exam are not enough to diagnose you with lung cancer. But they can help your healthcare provider figure out how to move forward and order additional testing if needed. 

Blood Tests

Though blood tests alone cannot diagnose you with lung cancer, they can help your care team get an overall sense of your general health—so, it is standard practice to get blood tested. 

Generally, your blood test will show a complete blood count (CBC), which can point to any concerns in the number of white blood cells, red blood cells, platelets, and other cell types. If something in your blood tests doesn’t look normal, your care team can order blood chemistry tests for further evaluation.

A blood chemistry test examines the cells in your organs. These tests can look at the function of your liver, kidneys, and other major organs. If your care team notices abnormal test results, it can mean that the cancer has spread to areas outside of the lungs. 

Keep in mind: You may be asked to come in for blood testing regularly if you receive a cancer diagnosis. Routine blood tests can help your care team understand how your treatment is working and monitor the status of your overall health.

Imaging Tests

Imaging tests create detailed pictures of your lungs by using technology such as sound waves, magnetic fields, or X-rays. These tests can detect if you have cancer cells or a tumor, how far the cancer has spread, and whether or not treatment is working. Your care team may order one or more of the following imaging tests:

Type of Imaging Test  Description
Chest X-ray Takes radiographic pictures to check the structure of the organs in the chest 
Magnetic resonance imaging (MRI) Uses magnets and radio waves to take images of the soft tissue in your chest to check if the cancer has spread to other organs
Computed tomography (CT scan) Combines several X-ray images to show a more detailed visual of the lungs, potential tumors, and enlarged lymph nodes 
Positron emission tomography (PET scan) Injects a safe radioactive material intravenously (with an IV) to look for chemical changes to your cells and organs
Bone scan Determines if the cancer has spread to your bones

Lab Testing 

Though blood and imaging tests can give your care team a better sense of your health, an official lung cancer diagnosis requires laboratory tests that look at your lung cells. There are several types of lab tests that your care team may use to make a lung cancer diagnosis and check to see how far the cancer has spread. 

Tests for Diagnosis 

A lab technician will perform tests by using a sample of your lung cells under a microscope. Some lab tests that your providers may order to confirm a lung cancer diagnosis include:

  • Sputum cytology: A test that asks you to cough up a sample of your sputum (mucus from your lungs) that checks if your mucus contains cancer cells.
  • Thoracentesis: Some people may have pleural effusion, or fluid buildup around the lungs. Your provider can perform this test by numbing the skin and inserting a small needle or catheter into the chest to drain a sample of fluid. A lab technician can test the fluid to determine what is causing the buildup. 
  • Bronchoscopy: This test looks at the inside of your lungs with a thin, flexible tube that is attached to a camera. A bronchoscopy checks for tumors or blockages in your airways. 
  • Biopsy: This diagnostic measure uses a needle to take a sample of your lung tissue. A lab technician will then view the sample under a microscope to check for cancer cells. 

Tests for Cancer Spread

If your care team finds cancer cells, they will likely order additional testing to see if the cancer has metastasized (spread). Lab tests can show where cancer cells have spread to and help inform your care team about treatment options that are right for you. These tests insert a thin tube that is attached to a tiny light and camera inside your body. This helps inspect cancer cells in different organs and structures in your body.

Your care team may order one or more of the following tests:

  • Thoracoscopy: This test inserts the tube under your shoulder blades to check for cancer cells that have spread outside of the lungs and into the chest. 
  • Endoscopic esophageal ultrasound: This ultrasound passes the tube down your throat to search nearby lymph nodes for cancer cells.  
  • Endobronchial ultrasound: This procedure moves the tube down the neck to check for cancer cells around the breastbone and in between the lungs. 
  • Mediastinoscopy or mediastinotomy: This exam puts the tube behind the breastbone to check for cancer cells in the mediastinum, which includes the heart, esophagus (throat), and trachea (windpipe). 

Lung Function Test

Also called a pulmonary function test (PFT), your care team may order this test after they make a lung cancer diagnosis. A lung function test can help your care team understand how well your lungs are working. 

There are several types of lung function tests, but they all generally have the same instructions: to breathe in and out of a tube. The tube is connected to a machine that measures your airflow.

In most cases, this test tells your providers whether it is safe to have lung surgery—which may be a treatment option, depending on the type of cancer you have. The lung function test informs how much of the lung a surgeon can remove, if needed for your treatment plan.

Stages of Cancer

When you receive a diagnosis of lung cancer, your care team will determine what stage of cancer you are in—based on where your cancer cells are and the size of your tumor. Your cancer stage will inform your care team about the treatment options that are right for you. 

The stages of cancer for SCLC and NSCLC are different. The stages of SCLC are:

  • Limited stage: Cancer cells are present in the lungs 
  • Extensive stage: Cancer cells have spread beyond the lungs into other lymph nodes and organs 

On the other hand, the stages of NSCLC are numbered and include: 

  • Stage 0: Cancer cells are present in the lining of the lungs but have not spread to the lung tissue
  • Stage 1: The cancer cells have developed into a small tumor (less than 3 centimeters) 
  • Stage 2: The tumor is larger than 3 centimeters and cancer cells have spread to nearby lymph nodes 
  • Stage 3: Cancer cells have spread to nearby organs in the chest 
  • Stage 4: The tumor can be any size and cancer cells have spread to the lung tissue and nearby or distant organs 

Screening for Related Conditions

Sometimes, lung cancer symptoms can mimic symptoms of other conditions. During your diagnostic process, your healthcare provider will also use testing to rule out other conditions. These conditions may include:

Condition  Description 
Pneumonia  Inflammation in one or both lungs caused by bacteria, fungi, or viruses 
Pneumothorax Air buildup—between the outside of the lung and within the pleural cavity (the space between your lungs and chest cavity)—which can cause the lungs to collapse partially or completely
Bronchitis Infection of the bronchial tubes in the lungs
Pleural effusion (caused by other conditions)  Fluid buildup in and around the lungs 
Tuberculosis Bacterial infection in the lungs 
Granuloma Non-cancerous inflammation of the lungs 
Hamartoma Non-cancerous growth of abnormal lung cells 

A Quick Review

Symptoms of lung cancer can vary depending on the type of cancer, the location, and the stage of cancer. If you think you may be at risk for lung cancer or begin to experience symptoms, it’s good practice to get tested.

Your healthcare provider will work with a pulmonologist and oncologist during your diagnostic process to run different tests. Common exams for lung cancer include physical, blood, imaging, lab, and lung function tests. These tests can help your care team confirm a diagnosis and rule out other conditions. 

Lung cancer is an aggressive condition—and getting tested can be scary. It’s OK to feel overwhelmed. But it’s important to remember that an early diagnosis can help you manage your condition and find a treatment plan that is right for you. 

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6 Sources uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Centers for Disease Control and Prevention. What is lung cancer?

  2. American Cancer Society. Early detection, diagnosis, and staging.

  3. American Cancer Society. Tests for lung cancer.

  4. National Cancer Institute. Lung cancer—patient version.

  5. Lung cancer risks, symptoms, and diagnosis (beyond the basics).

  6. American Lung Association. Lung cancer staging

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