What Is Non-Small Cell Lung Cancer?

Non-small cell lung cancer (NSCLC) is a type of cancer that begins in the tissues of the lungs, the two spongy organs in your chest that help your body absorb oxygen. Lung cancer is the third most common cancer affecting adults in the United States and the leading cause of cancer death. 

There are several types of non-small cell lung cancer including squamous cell carcinoma, large cell carcinoma, and adenocarcinoma. NSCLC makes up about 80-85% of all lung cancer diagnoses in the United States. It is estimated that smoking causes up to 90% of cases of lung cancer.

The common symptoms of non-small cell lung cancer are shortness of breath and a persistent cough. Fortunately, there are several treatment options available for NSCLC.

Types

There are many different types of lung cancer, and each one affects different types of cells and spreads in different ways. The main types of non-small cell lung cancer include: 

• Squamous cell carcinoma: This type forms in the thin, flat squamous cells in the lungs, which line the inside of the airways. It is also possible for it to develop in the skin.
• Large cell carcinoma: This begins in different types of large cells in the lungs.
• Adenocarcinoma: This starts in the cells that line the alveoli (small air sacs in the lungs). 
  

Non-Small Cell Lung Cancer Symptoms 

When NSCLC develops in the lungs, it affects your ability to breathe. Common symptoms may include: 

• Persistent cough
• Shortness of breath (dyspnea)
• Chest pain
• Wheezing
• Coughing up blood (hemoptysis)
• Hoarse voice
• Trouble swallowing (dysphagia)
• No appetite 
• Unintended weight loss
• Fatigue 

As NSCLC grows and spreads, it can start to affect other organs and areas of the body. Later symptoms may include:

• Bone pain
• Joint pain 
• Muscle weakness
• Eyelid drooping (ptosis) 
• Swelling in the face and neck

What Causes Non-Small Cell Lung Cancer? 

Non-small cell lung cancer occurs when certain cells in the lungs become damaged and begin to grow and multiply at an out-of-control rate. The most common cause of cell damage in the lungs is smoking. Researchers believe that up to 90% of all lung cancer cases are caused by smoking tobacco.

Risk Factors

The main risk factor for NSCLC is smoking. The earlier a person starts smoking and the more often they smoke, the higher their risk for lung cancer. 

Other risk factors include:

• Second-hand smoke exposure 
• Workplace exposures to chemicals including asbestos, radon, chromium, beryllium, nickel, soot, or tar
• History of radiation therapy to the breast or chest
• History of frequent imaging tests
• Exposure to atomic bomb radiation 
• Exposure to air pollution
• Family history of lung cancer
• Human immunodeficiency virus (HIV)
• Beta carotene supplements (for heavy smokers only)
• Older age
• Gene mutations such as the KRAS-G12C mutation, which is found in 13% of people with NSCLC

Diagnosis

Non-small cell lung cancer is usually diagnosed by an oncologist, a medical doctor who specializes in the diagnosis and treatment of cancer. If your healthcare provider is concerned that you have symptoms of lung cancer, you will likely be referred to an oncologist who specializes in lung cancer. 

Medical tests used to diagnose NSCLC include:

• Physical exam: The oncologist will perform a thorough physical exam to look for signs of cancer. 
• Health history: Your oncologist will ask questions about your health history and risk factors to understand your cancer risk. 
• Lab tests: Your oncologist may order lab tests of tissues, blood, and urine to look for signs of cancer or infection. 
• Chest X-ray: You may need a chest X-ray to rule out other causes of lung cancer symptoms such as pneumonia or another infection. 
• Sputum cytology: A pathologist examines a sample of your sputum (mucus) under a microscope. 
• Thoracentesis: A healthcare provider removes fluid from the space between the lungs and chest wall, and then examines it under a microscope. 
• Endoscopic ultrasound: A healthcare provider inserts a scope down the throat to produce pictures of the lungs. 
• Bronchoscopy: The oncologist may use a bronchoscopy to look inside the trachea (windpipe) and the large airways. 
• Mediastinoscopy: A surgeon makes an incision in the breastbone and guides a scope into the chest to examine the lungs and take a biopsy if needed. 
• Lymph node biopsy: If your oncologist is concerned that cancer has spread to the lymph nodes, they may remove all or part of a lymph node to test it for cancer cells. 

Once you have been diagnosed with non-small cell lung cancer, your oncologist may order additional tests to determine how advanced the cancer is. These tests can include:

• Magnetic resonance imaging (MRI): An MRI uses magnets and radio waves to produce detailed pictures of the lungs and surrounding tissues. 
• Computed tomography (CT) scan: A CT scan provides detailed pictures by taking several X-rays from different angles.
• Positron emission tomography (PET) scan: A PET scan finds fast-growing cells in the body to tell how far cancer has spread.
• Bone scan: Your oncologist may recommend a bone scan to determine if cancerous cells have spread to the bone.
• Pulmonary function test (PFT): PFTs can be used to tell how well the lungs are working. 

Stages of Non-Small Cell Lung Cancer

Treatment for non-small cell lung cancer depends on the stage. Cancer staging is used to determine how far cancer has spread throughout the body. 

The stages of NSCLC include:

• Occult (hidden) stage: Cancer cells cannot be detected with imaging or bronchoscopy but can be found in the sputum.
• Stage 0: Cancer cells are present in the lining of the airways but have not spread beyond the lungs.
• 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 between 3 and 4 cm and has not spread to the lymph nodes.
• Stage IIA: The tumor is between 4 to 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 liver or the brain.  

Treatments for NSCLC

The treatment for non-small cell lung cancer depends on the cancer stage, symptoms, and your overall health. There are several possible treatment options, and your oncologist will recommend a plan based on your individual health. 

The goal of treatment for people with stage I or stage II NSCLC is to cure cancer. The goal of treatment for those with stage III or stage IV is usually to extend life and improve quality of life. 

If the tumor can be removed, surgery is usually the first treatment option. Surgical options include:

• Wedge resection: Remove the tumor and the surrounding normal tissue
• Lobectomy: Remove the entire lobe of the lung
• Pneumonectomy: Remove the whole lung
• Sleeve resection: Remove part of the bronchus 

If cancer cells have spread beyond the lungs, you may require additional treatments, including:

• Radiation therapy: Radiation therapy uses high-energy rays or particles to destroy cancer cells. It may be useful after surgery to kill any remaining cancer cells.
• Chemotherapy: Chemotherapy includes drugs used to destroy cancer cells. 
• Immunotherapy: Immunotherapy supports the body’s immune system so it can better fight cancer.  
• Laser therapy: Laser therapy uses a laser beam to destroy cancer cells.
• Photodynamic therapy (PDT): PDT combines light energy with drugs that help destroy cancer cells when activated by light.
• Cryosurgery: Cryosurgery freezes and destroys abnormal tissue to stop cancer from spreading.  
• Electrocautery: Electrocautery uses a heated needle or probe to destroy cancerous tissue.

Another treatment option for non-small cell carcinoma is targeted therapy. Targeted therapy uses drugs to help the body identify specific cancer cells. Targeted therapy options include:

• Monoclonal antibodies: Monoclonal antibodies are able to attach to specific targets on cancer cells.
• Tyrosine kinase inhibitors: These drugs enter the cell membrane and tell cancer cells to stop growing and dividing. 
• Mammalian target of rapamycin (mTOR) inhibitors: These drugs block the mTOR proteins (which coordinate cell growth) to keep cancer cells from growing and dividing. 
• KRAS G12C inhibitors: These inhibitors block the KRAS-G12C mutation to keep them from growing more cancer cells. 
  

Prevention

Not all cases of non-small cell lung cancer can be prevented. However, it is possible to significantly lower your risk. Because smoking causes a majority of lung cancer cases, avoiding tobacco is the best way to prevent lung cancer. 

If you currently smoke, talk with your healthcare provider about resources to help you quit. There are prescription medications and support groups that may help. 

Related Conditions  

People with NSCLC are at an increased risk of developing other types of cancer in the future. If you have a history of cancer, talk with your healthcare provider about regular cancer screenings. 

People with NSCLC are at an increased risk of certain complications, including: 

• Pneumonia: Infection and inflammation in the lungs 
• Thrombosis: Blood clot, which can start in or travel to the lungs (pulmonary embolism) 
• Paraneoplastic syndrome: A group of symptoms that occur when the immune system reacts to cancer
  

Living With Non-Small Cell Lung Cancer

Many people with non-small cell lung cancer can be cured with successful treatment. However, some people may live with this type of cancer without a cure. Lung cancer is the leading cause of cancer death in the United States. 

Fortunately, there are several treatment options and resources available as you navigate living with NSCLC. People with this type of lung cancer can expect to regularly meet with their healthcare team for follow-up exams, imaging tests, and screenings.

If you or a loved one with NSCLC smokes cigarettes or uses other tobacco products, joining a smoking cessation program can help with quitting. You may also find further resources and support by joining a lung cancer support group and/or seeing a therapist.