What Is Squamous Cell Carcinoma (SCC) of the Lung?

older man discussing lung cancer with this doctor

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Squamous cell carcinoma (SCC) of the lung is a type of non-small cell lung cancer. It starts in the squamous cells (flat cells) that line the inside of the airways, unlike other types of lung cancer cells that usually develop in the central part of the lungs or main airway (bronchus). 

Exposure to tobacco smoke is a major risk factor for squamous cell lung carcinoma. It is estimated that smoking causes up to 80% of cases in those assigned male at birth and 90% of cases in those assigned female at birth. 

Symptoms of squamous cell lung carcinoma include a chronic cough, chest pain, and fatigue. Treatment options vary based on the cancer stage and your overall health. Options include chemotherapy, radiation therapy, and surgery. 

Types of NSCLC

Squamous cell lung carcinoma is a type of non-small cell lung cancer (NSCLC). The most common types of NSCLC include:

  • Squamous cell lung cancer: Starts in the squamous cells that line the airways
  • Adenocarcinoma: Starts in the cells that secrete mucus
  • Large cell carcinoma: Can start in any part of the lung and tends to grow and spread quickly

The three subtypes of squamous cell carcinoma include:

  • Keratinizing squamous cell carcinoma
  • Nonkeritanizing squamous cell carcinoma
  • Basaloid squamous cell carcinoma

Squamous Cell Lung Carcinoma Symptoms 

Squamous cell lung carcinoma usually does not cause symptoms in the early stages. This means that it is often diagnosed in a later stage once symptoms begin. 

Symptoms of squamous cell lung carcinoma may include:

  • Persistent cough
  • Chest pain
  • Coughing up blood (hemoptysis)
  • Malaise (feeling unwell)
  • Unintended weight loss
  • Shortness of breath
  • Hoarseness 
  • Wheezing
  • Recurring lung infections (bronchitis, pneumonia)

What Causes SCC of the Lung?

Squamous cell lung carcinoma occurs when cancer cells develop in the squamous cells that line the airways. There is a strong connection between smoking and this type of lung cancer. People who smoke are at a 10 times higher risk of developing squamous cell lung carcinoma than those who don’t. 

Researchers estimate that exposure to tobacco smoke causes 80% of cases in people assigned male at birth and 90% of cases in people assigned female at birth. Tobacco smoke contains over 300 harmful agents and 40 potential cancer-causing agents (carcinogens). 

Risk Factors

While smoking is the main risk factor for squamous cell lung carcinoma, there are other factors to be aware of. Risk factors include:

  • Increasing age
  • Long-term exposure to secondhand smoke
  • Workplace exposure to certain chemicals (asbestos, arsenic, chromium, beryllium, nickel, and others)
  • Radiation therapy to the breast or chest area
  • Radon exposure at home or work 
  • Frequent imaging tests
  • Atomic bomb exposure 
  • Air pollution 
  • Family history 
  • Human immunodeficiency virus (HIV)
  • Beta carotene supplements (in people who smoke heavily)

Diagnosis

If you develop symptoms of lung cancer such as a chronic cough or shortness of breath, your healthcare provider will perform a thorough physical exam. They will also ask questions about your medical history and smoking status. 

In addition to taking your medical history, your healthcare provider may perform the following diagnostic tests:

If you have a history of smoking heavily, your healthcare provider may recommend regularly screening you for lung cancer with low-dose CT scans.

Lung Biopsy Results

Once your healthcare provider obtains a lung biopsy, they will send the sample to the lab for a pathologist to examine it under a microscope. The pathologist will then write a report based on their findings. 

A pathologist may detect cancer or pre-cancer. Precancerous conditions refer to abnormal changes in the cells that have not turned into cancer. 

Pre-cancers that may lead to squamous cell lung carcinoma include: 

  • In-situ carcinoma: Carcinoma (cancer) cells present in the top layer of cells in the airways (bronchi, bronchioles, or alveoli) but not in the deeper layers
  • Squamous metaplasia: Irritation in the air passages that occurs when the cells lining the passage change their shape and begin to flatten and stack on top of each other
  • Squamous dysplasia: An early form of pre-cancer that occurs when the squamous cells lining the air passages look abnormal but not cancerous

Stages of Squamous Cell Lung Carcinoma 

After evaluating your tests and biopsies, your healthcare team will stage the disease. Lung cancer staging is used to determine how advanced a person’s cancer is. Healthcare providers typically use the TNM system developed by the American Joint Committee on Cancer to determine the extent of squamous cell lung carcinoma. The TNM system uses three criteria:

  • T for tumor: Size of tumor(s)
  • N for nodes: Lymph node involvement 
  • M for metastasis: If the cancer has metastasized (spread) to other areas of the body

Squamous cell lung carcinoma does not typically cause symptoms in the early stages and is usually diagnosed in later stages. Stages for non-small cell lung cancer include:

  • Stage I: Cancer cells present in the lung tissue but have not spread to the lymph nodes
  • Stage II: Cancer cells have spread to the airways or lymph nodes
  • Stage III: Cancer cells have spread to the lymph nodes and other areas of the chest
  • Stage IV: Cancer cells have spread to distant areas of the body such as the brain or bones

Treatments for Squamous Cell Lung Carcinoma  

Treatment for squamous cell lung carcinoma depends on the cancer stage and your overall health. This type of lung cancer is usually less sensitive to chemotherapy and radiation therapy than other types. This means that these treatments are typically less effective. 

If possible, surgery is the first-line treatment for stages I and II of squamous cell lung carcinoma. The treatment options by stage include:

  • Stage I: Surgical removal (resection) of the tumor and surrounding tissue, followed by chemotherapy
  • Stage II: Surgical removal (resection) of the entire lobe of the lung where cancer is found, followed by chemotherapy
  • Stage III: Chemotherapy and radiation therapy; surgery may be possible once the tumor has shrunk
  • Stage IV: Chemotherapy for pain relief and palliative purposes; cure is not possible

Your healthcare team may recommend radiation therapy if cancer cells are detected after you complete surgery and chemotherapy. 

If other treatments have not been successful and you are healthy enough for surgery, your healthcare team may recommend removing the entire lung (pneumonectomy). 

Lung cancer surgery is not safe for everyone. Your provider may decide that you are not healthy enough for surgery if you have a history of heart disease, chronic obstructive pulmonary disease (COPD), tuberculosis, pulmonary hypertension, or bronchiectasis. 

Prevention

It is not always possible to prevent squamous cell lung carcinoma. The most effective way to significantly lower your risk is to avoid tobacco smoke. Smoke from cigarettes, cigars, and pipes is harmful to your lung health and may lead to cancer. If you are interested in quitting smoking, talk with your healthcare provider about resources such as medications and support groups. 

Complications 

As squamous cell lung carcinoma grows and spreads, it can lead to serious complications. You may experience shortness of breath if the tumor blocks your airway. You may also experience bleeding and coughing up blood if the tumor irritates the air passages. 

When squamous cell lung carcinoma metastasizes to other areas of the body, it may cause several new symptoms depending on which organs and tissues are affected. Possible complications include:

  • Bone pain
  • Headaches
  • Weakness
  • Numbness
  • Dizziness
  • Seizures 

Living With SCC of the Lung

It is possible to live with squamous cell lung carcinoma. Your healthcare provider will discuss survival rates and your prognosis with you. Squamous cell lung carcinoma is a type of non-small cell lung cancer. The 5-year survival rates for NSCLC are:

  • Localized stage (has not spread beyond the lungs): 65%
  • Regional stage (has not spread beyond the chest area): 37%
  • Distant stage (has spread to other areas of the body): 9%
  • All stages combined: 28%

The prognosis for squamous cell carcinoma tends to be worse if cancer is diagnosed in a later stage, has spread to other areas of the body, or the tumor is over 3 centimeters wide.

Your healthcare team will work with you to develop a comprehensive treatment plan to fight the cancer while improving your symptoms and quality of life. Studies show that participating in an exercise rehabilitation program before lung cancer surgery can significantly improve your outcomes and lower the risk of complications.

Frequently Asked Questions

  • What is the life expectancy of squamous cell lung cancer?

    The overall 5-year survival rate for non-small cell lung cancer is 28%. Your life expectancy will depend on the cancer stage and your overall health.

  • Is squamous cell carcinoma lungs treatable?

    Squamous cell lung carcinoma is treatable. In the early stages, your healthcare team will likely recommend surgery and chemotherapy. In later stages, your team may recommend chemotherapy and radiation therapy. Treatment success depends on several factors, including how advanced the cancer is and your overall health. 

  • What size squamous cell carcinoma is considered large?

    Squamous cell lung carcinoma tumors larger than 3 to 4 centimeters are considered large and may not be able to be removed surgically. Your healthcare team may recommend chemotherapy to shrink the tumor before considering surgery.

Edited by
Dana Ingemann
Dana Ingemann
Dana is an Associate Editorial Director at Health, leading the development and strategy of new evergreen content. Dana holds a Master's in Public Health and is a Certified Health Education Specialist (CHES).
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