Squamous cell lung carcinoma is a type of non-small cell lung cancer (NSCLC). According to the American Cancer Society, about 80 to 85 percent of all lung cancers are non-small cell.

Squamous cell lung carcinoma begins in the top layer of cells, called squamous cells, that line the large airways (bronchi) of the lung. It usually grows in the bronchi that branch off of the main left or right bronchus in the center of the chest.

As of 2015, the World Health Organization classifies three subtypes of squamous cell lung carcinoma. These are based on how the cancer cells appear under a microscope and include:

  • keratinizing squamous cell carcinoma
  • nonkeratinizing squamous cell carcinoma
  • basaloid squamous cell carcinoma

The National Cancer Institute estimates that squamous cell lung carcinoma makes up 25 percent of all lung cancers. Of all the types of non-small cell cancers, squamous cell lung carcinomas have the strongest connection to smoking.

Squamous cell lung carcinoma begins in the cells lining the bronchi. Over time, cancer can spread by invading nearby lymph nodes and organs and traveling through the blood (metastasizing) to other parts of the body.

Doctors use tumor size, location, and severity of spread to classify cancer into stages. Using the TNM system, the cancer is given a number indicating tumor size (T), spread to the lymph nodes (N), and metastasis (M). These are then combined to classify the cancer into a stage.

There are six main stages. Stages 1 to 4 are subdivided according to tumor size, number, and location:

Occult stage

Occult means hidden. In this stage, there are cancer cells in the sputum or other fluids from the lung. However, other tests cannot determine the location of a tumor.

Stage 0

The cancer is only in the lining of the bronchus and not in lung tissue. This is also called carcinoma in situ.

Stage 1

In stage 1, the cancer is only in the lung. It hasn’t spread to the lymph nodes around it or other parts of the body.

Stage 2

In stage 2, cancer is in the lung tissue and has spread into the lining of the lung or nearby lymph nodes but hasn’t metastasized further.

Stage 3

Stage 3 cancer is in the lung tissue and has spread to nearby lymph nodes or organs, such as the esophagus or heart, but hasn’t spread to distant organs.

Stage 4

In stage 4, the cancer is in the lung tissue and has spread to one or more distant parts of the body. Stage 4A means cancer has spread as one tumor, or it’s spread to the other lung or the fluid around the heart or lungs. In stage 4B, it’s metastasized as two or more tumors.

Treatment for squamous cell lung carcinoma depends on how advanced the cancer is, your ability to tolerate the side effects, and your overall health. Age isn’t usually a consideration.

The treatment you receive will be specific to your situation, but there are some general guidelines for the treatment of each stage.

Occult cancer

If you have cancer cells in your sputum but no cancer is found with diagnostic tests, you’ll usually undergo frequent diagnostic tests (such as a bronchoscopy or CT scan) until a tumor is found.

Stage 0

Surgical removal of the tumor and lung around it without chemotherapy or radiation therapy usually cures squamous cell carcinoma at this stage. This is because cancer hasn’t spread deeper into the tissue of the lungs.

Stage 1

Surgery alone often works at this stage. Some lymph nodes are usually removed to see if cancer has spread to them.

If cancer cells are found close to the edges of the tissue removed, that could mean that some cancer cells have been left behind. A second surgery may be necessary to ensure all cancer cells have been removed.

If the risk of the cancer coming back is high, you might receive chemotherapy after surgery. Occasionally, radiation therapy is used instead of chemotherapy.

Stage 2

This stage is usually treated with surgical removal of the tumor and lymph nodes followed by chemotherapy to kill any remaining cancer cells.

If the tumor is large, you may receive chemotherapy and radiation therapy or radiation alone before surgery to make the tumor smaller and easier to remove with surgery.

Stage 3

Surgery alone can remove some but not all of the cancer in this stage, as it’s spread to lymph nodes in your neck or vital structures in your chest. Chemotherapy and radiation therapy are usually given after surgery.

In situations where the treatments above aren’t good options, immunotherapy may be used. This is a type of treatment that helps your immune system fight cancer.

Stage 4

In this stage, cancer has spread throughout your body. Treatment depends on your overall health and how many places the cancer has spread. If you’re healthy enough to undergo surgery, you may have a combination of surgery, chemotherapy, and radiation therapy.

Other therapies that may be added to your treatment or used if surgery isn’t an option are:

If treatment isn’t effective or a person decides to stop treatment, palliative care is often given. This is supportive care used to improve the quality of life for people with advanced cancer. It can help relieve cancer symptoms and provide emotional support to the person with cancer and their loved ones.

Hospice is palliative care that’s given when the estimated life expectancy is less than 6 months.

Many people don’t experience symptoms of squamous cell lung carcinoma until cancer has begun to spread. Some of the most common symptoms are:

It’s also possible that people with squamous cell lung carcinoma may experience recurring lung infections. These can include things like pneumonia or bronchitis.

Some symptoms that squamous cell lung carcinoma may have spread (metastasized) to other areas of the body include:

Metastasis is when a cancer spreads to other parts of the body. This may include lymph nodes, the other lung, or other organs.

It’s estimated that metastatic cancer is present at the time of diagnosis in about 40 percent of people with non-small cell lung cancer. Many individuals with non-small cell lung cancer don’t experience symptoms until cancer has started to spread.

For squamous cell lung carcinoma, some of the most common metastatic sites are the:

It’s also possible that squamous cell lung carcinoma can spread to several areas of the body. For example, cancer could spread from the lung to both the bone and the brain.

Treatment for cancer that has metastasized can depend on several factors, such as your overall health, where the cancer has spread, and how you’ve responded to treatment. Your treatment team will work with you to recommend an approach that best suits your individual treatment needs.

Some of the causes and risk factors for squamous cell lung carcinoma include:

Smoking

Of all the causes of lung cancer, smoking is by far the most important. According to the National Cancer Institute, smokers are 10 times more likely to get any lung cancer than people who have smoked fewer than 100 cigarettes.

The more you smoke, and the longer you smoke, the higher the risk. If you quit smoking, your risk for lung cancer goes down but stays higher than for nonsmokers for several years after quitting.

The risk of getting lung cancer is almost as high for cigar and pipe smoking as for cigarettes.

Radon exposure

The U.S. Environmental Protection Agency lists radon as the second leading cause of lung cancer. It’s also the most common cause of lung cancer in nonsmokers.

Radon is a radioactive, odorless, invisible gas from rocks and soil. It’s only a problem in enclosed places, such as a house, because the concentration of radon is higher. People who smoke and are exposed to radon have a much higher risk for lung cancer.

Secondhand smoke exposure

Being exposed to secondhand smoke can increase your risk of lung cancer.

Other causes

Other causes include:

  • Exposure to cancer-causing substances. Examples include asbestos, arsenic, chromium, nickel, and some petroleum products. Exposure to these substances most often occurs at work.
  • Air pollution. Poor air quality can lead to or exacerbate certain conditions, but there are ways to protect yourself.
  • Radiation exposure. This may include previous treatment with radiation therapy to your chest or excessive exposure to radiation from getting X-rays.
  • Medical history. A personal or family history of lung cancer increases your risk for lung cancer. If you’ve had lung cancer, you have a higher risk of getting it again. If a close relative had lung cancer, you have a higher risk of getting it.

To diagnose squamous cell lung carcinoma, your doctor will first ask you about your symptoms and do an examination.

Next, they’ll do one or more diagnostic tests depending on your history, symptoms, condition, and tumor location. These tests may include:

Lung imaging

Usually, a chest X-ray is done first. They’ll then do a CT scan or MRI to get a better view of your lungs and look for a tumor and signs that cancer has spread.

Obtaining some cancer cells

There are a few ways your doctor can obtain these cells. They may take a sputum sample. If there is any fluid around your lungs, it will usually have some cancer cells, too. Your doctor may obtain a sample with a needle inserted through your skin (thoracentesis). Then, your cells are examined under a microscope for signs of cancer.

Biopsy

A biopsy is another way to look at cells under a microscope. Your doctor can take a biopsy of the tumor using a needle inserted through your skin (needle biopsy) or a tube with a light and camera that’s inserted through your mouth or nose (bronchoscopy).

If cancer has spread to the lymph nodes or other structures between your lungs, your doctor can do a biopsy through an incision in your skin (mediastinoscopy).

PET scan

This is an imaging test that shows a bright spot in any tissue where there’s cancer. PET scans are used to look for metastases near the tumor or in the body.

Bone scan

This is an imaging test that shows a bright spot in areas of bone where cancer has spread.

Pulmonary function tests

These test how well your lungs work. They’re used to show if you’ll have enough lung function left after surgical removal of the lung tissue with the tumor.

Molecular tests

These tests can see if cancer cells have certain types of gene mutations or express specific types of proteins on their surface. Molecular tests can be helpful for determining if targeted therapy or immunotherapy may be effective.

The outlook for non-small cell lung cancers, such as squamous cell carcinoma, is better than for small cell lung carcinomas. It’s also better when it’s caught and treated early. In fact, it can even be cured if caught early enough.

The outlook for people with cancer is measured by 5-year survival rates. This indicates the percentage of people who have a specific type of cancer who are alive 5 years or more after getting a diagnosis.

The American Cancer Society uses data from the National Cancer Institute to track the average 5-year survival rates for non-small cell lung cancers. It does this based on if and how cancer has spread:

  • Localized: This is non-small cell lung cancer that hasn’t spread outside of the lung. The 5-year survival rate is 63 percent.
  • Regional: This is non-small cell lung cancer that has spread to the lymph nodes and other nearby organs in the chest. The 5-year survival rate is 35 percent.
  • Distant: This is when non-small cell lung cancer has spread to more distant organs of the body, such as the liver, brain, or bones. The 5-year survival rate is 7 percent.

It’s important to remember that these percentages are only a guide based on averages. Everyone is different. The percentages show that the key to having the best outlook is early detection and treatment before cancer spreads.

The outlook for an individual person is influenced by many factors, such as age, general health, response to treatment, and treatment side effects. Your doctor will evaluate all of this information to give you an outlook that’s specific to you.

Squamous cell lung carcinoma is a type of non-small cell lung cancer. It impacts the cells that line the surface of your airways. There are three types of squamous cell lung carcinoma based on how the cells look under a microscope.

Squamous cell lung carcinoma can occur in six stages. Staging is done based on tumor size and whether cancer has spread to the lymph nodes or other parts of the body. Many people don’t have symptoms until the cancer has begun to spread.

There are many treatment options for squamous cell lung carcinoma. The treatment that’s recommended can depend on various factors, such as the stage of cancer, overall health, and the presence of specific mutations in the cancer cells.

You can significantly decrease your risk for lung cancer by not smoking and avoiding radon or secondhand smoke exposure. The overall outlook improves with early diagnosis and treatment, so be sure to talk with a medical professional if you’re concerned about developing lung cancer.