How Is Non-Small Cell Lung Cancer Diagnosed?

Non-small cell lung cancer (NSCLC) is a type of cancer that starts in the cells that line the surface of the lung airways. About 80-85% of people with lung cancer in the United States are diagnosed with NSCLC. While anybody can develop the cancer, people who smoke are at the highest risk of developing NSCLC. 

An oncologist (a medical doctor specializing in diagnosing and treating cancer) usually diagnoses NSCLC with several tests and exams. Your medical team will also likely include a pulmonologist (a medical doctor specializing in diagnosing and treating lung conditions).

To diagnose NSCLC, your healthcare team will likely recommend a medical history, physical exam, blood tests, imaging studies, procedures, and a biopsy.  

Medical History 

To determine if you have non-small cell lung cancer, your healthcare provider will likely begin by asking several questions about your health history, family history, and current symptoms.

The most common cause of non-small cell lung cancer is a history of smoking. Other risk factors include exposure to radon, asbestos, secondhand smoke, and other chemicals. 

Your provider will also probably ask if you have any of the following common NSCLC symptoms:

• Persistent cough
• Shortness of breath
• Chest pain
• Wheezing
• Blood when coughing
• Hoarse voice
• Trouble swallowing 

As NSCLC progresses, it may cause a lack of appetite, unintended weight loss, and fatigue. 

Physical Exam

The next step in diagnosing NSCLC is a physical exam. Your provider will likely conduct a thorough exam, paying special attention to your lungs and chest area.

Your provider will listen to your lungs with a stethoscope and ask you to take deep breaths. The provider can hear your lungs by placing the stethoscope's metal disc on your body and listening with the tool's earpieces, which are connected to the disc by two tubes.

Your provider will also examine your face and neck for signs of swelling or enlarged veins. 

Imaging

After conducting a medical history and physical exam, your healthcare provider will likely order a chest X-ray (CXR) to look for a tumor (masses) in the lungs. A chest X-ray is a painless test that can detect lung masses. 

Your provider may also recommend a chest computerized tomography (CT) scan because it can detect smaller growths in the lungs. 

Lab Tests 

Your healthcare provider may request laboratory tests of your blood and urine to look for signs of cancer or infection. A complete blood count (CBC) measures the number of red blood cells, white blood cells, and platelets in your blood. People with cancer usually have abnormal values of these types of cells. 

Your healthcare team may also recommend pulmonary function tests (PFTs). These tests measure lung function and determine how much air the lungs can hold. If you have been coughing up mucus (sputum), your provider may take a sample to examine it under a microscope and look for cancer cells. 

Procedures

Several types of procedures can help your healthcare team get a closer look at your lungs and determine if cancer cells are present.

Your healthcare provider may start with a bronchoscopy. This procedure involves placing a tube with a camera (scope) down your airway and into the lungs to examine the tissue and take samples. If your provider sees a concerning area or growth, they will take a tissue sample and send it to the lab for testing. This sample is known as a biopsy. 

Other procedures to inspect the lungs include thoracentesis (removing fluid from the space between the lungs and chest wall) and mediastinoscopy (placing a scope into the chest through an incision).

Staging Tests

Once you have been diagnosed with NSCLC, your healthcare team may recommend additional tests to determine how advanced the cancer is.

A positron emission tomography (PET) scan is an imaging study used to detect fast-growing cells in the body. This test can help your team determine if and how far cancer has spread beyond the lungs. 

If your provider is concerned that cancer has spread, they may recommend a bone scan to look for cancer cells in the bones and a lymph node biopsy to learn if there are cancer cells in the lymph nodes. 

Genetic Testing 

Certain gene mutations may raise the risk of NSCLC. Once you have been diagnosed, your healthcare provider may recommend genetic testing to determine your most effective treatment plan. You may benefit from targeted therapy if you have NSCLC and any mutations in the following genes:

• CHEK2
• ATM
• TP53
• BRCA1
• EGFR
• APC
• PALB2
  

Stages of Non-Small Cell Lung Cancer 

Once a person has been diagnosed with cancer, their healthcare team conducts additional tests to determine the cancer stage. The stage describes how advanced the cancer is and how far it has spread. This helps to determine a person’s treatment plan and prognosis. 

The staging of NSCLC is complex and detailed. A brief summary of staging includes:

• Occult (hidden) stage: Cancer cells cannot be detected with imaging or bronchoscopy but can be found in the mucus.
• Stage 0: Cancer cells are present in the lining of the airways but have not spread deeper in the lung tissue.
• Stage IA: The cancerous tumor is no larger than 3 centimeters (cm) and has not spread to the lymph nodes. 
• Stage IB: The tumor is larger than 3 cm but not larger than 4 cm and has not spread to the lymph nodes.
• Stage IIA: The tumor is larger than 4 cm but not larger than 5 cm and has not spread to the lymph nodes. 
• Stage IIB: The tumor is not larger than 5 cm but has spread to the lymph nodes.
• Stage III: Cancer cells have spread to areas on the same side of the chest as the primary tumor. 
• Stage IV: Cancer cells have spread to distant areas of the body, such as the bones or the brain.  
  

Screening for Related Conditions

There are benign (non-cancerous) conditions and infections that may cause symptoms similar to NSCLC. When you develop symptoms of lung cancer such as a persistent cough, your healthcare provider may perform exams and tests to rule out a lung infection like pneumonia (inflammation in the lungs). They may also look for signs of thrombosis, a blood clot in the lungs.

A Quick Review

Non-small cell lung cancer (NSCLC) is a type of lung cancer that begins in the cells that line the airways. NSCLC is the most common type of lung cancer in the United States. To determine if you have NSCLC, your primary healthcare provider will likely refer you to an oncologist or pulmonologist. 

Your healthcare team will likely start the diagnostic process with a medical history and physical exam to understand your risk and look for signs of cancer. They may also order imaging studies, blood tests, pulmonary function tests, and procedures such as a lung biopsy.