Squamous cell carcinoma of the lung is a type of non-small cell lung cancer (NSCLC). It begins in the top layer of the cells, also known as the squamous cells, lining the lung’s large airways (bronchi). This cancer usually grows in the bronchi that branch off the primary right or left bronchus in the center of the chest.
As the tumor increases in size, a CT scan or a chest X-ray may detect a cavity in the lung. This cavity is a fluid or gas-filled space within a tumor nodule or mass, and it is the most common sign of squamous cell lung cancer. Eventually, this cancer may spread to multiple sites as it grows, including the bones, adrenal glands, liver, brain, and spine.
According to the American Center Society, around 80% to 85%¹ of all lung cancers are non-small cell lung cancer.
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Generally, most people do not experience any symptoms of squamous cell lung carcinoma until cancer has spread. However, when these symptoms do occur, they often include:
Wheezing or shortness of breath
A hoarse voice
Constant cough or coughing up blood
Chest pain, usually when coughing or taking a deep breath
A bloody sputum
A decreased appetite
Unexplained weight loss
Neurological symptoms if cancer has spread to the spine
If the squamous cell lung carcinoma has spread to the other areas of the body, symptoms may also include:
Dizziness or headaches
Swollen lymph nodes
Limb numbness or weakness
To get an accurate squamous cell carcinoma diagnosis, you need to see a doctor. Healthcare professionals will start by reviewing your symptoms and performing a physical examination. Depending on your symptoms, personal history, and tumor location, you will have one or more diagnostic tests. These tests often include:
A CT or MRI scan can assess how much cancer has spread. A PET scan shows a bright spot in any tissue where there is cancer.
Your doctor can biopsy the tumor using a needle or a tube with a camera and light inserted through your mouth. If cancer has spread to other structures, your doctor can also perform a biopsy through an incision.
Pulmonary function tests (PFTs)
These tests will assess how your lungs are working. If your cancer is isolated or small, they can determine if you can undergo surgery.
These tests look at whether cancer has a gene mutation or a specific type of protein on its surface. Doctors often use these tests to evaluate whether immunotherapy or targeted therapy may be effective.
Once your medical professional has confirmed the squamous cell carcinoma of the lung, they use the tumor's location, size, and spread to classify the cancer's stage.
Typically, squamous cell carcinoma of the lungs is broken down into the following stages:
Stage 0: The cancer is only in the lining of the bronchus and not in any lung tissue.
Stage I: The cancer is localized in the lungs and has not spread to any lymph nodes.
Stage II: The cancer in the lung tissue has spread into nearby lymph nodes.
Stage III: The cancer in the lung tissue has spread to lymph nodes in the middle of the chest.
Stage IV: The cancer in the lung tissue has spread to another part of the body, including the liver, brain, bones, or adrenal glands.
The size of the tumor and the degree of spread determines the stage of cancer.
Several risk factors² and causes are associated with squamous cell carcinoma of the lung, including:
In general, smoking is one of the leading risk factors when it comes to lung cancer. Almost 80% of all lung cancer deaths result from smoking. The longer you smoke and the more packs you smoke per day, the greater your risk of getting lung cancer.
Cigar, pipe, and "light" cigarette smoking
Those that smoke cigars or pipes have almost the same risk of getting lung cancer as cigarette smokers. In addition, smoking "light" cigarettes or low-tar cigarettes increases lung cancer risk as much as other regular cigarettes. However, those that smoke menthol cigarettes may have an even greater risk of developing lung cancer since menthol often allows a smoker to inhale more deeply.
Even if you do not smoke, breathing in smoke can increase your risk of developing lung cancer. This can include breathing in secondhand smoke (environmental tobacco smoke.)
Radon is a radioactive gas that occurs naturally when uranium breaks down in rocks or soil. This invisible gas cannot be tasted or smelled, but when someone breathes in radon, it exposes their lungs. According to the U.S. Environmental Protection Agency³, radon is the second leading cause of lung cancer, and it is the most common cause of lung cancer in non-smokers.
Although there may be some radon outdoors, the amount is minuscule and unlikely to be dangerous. However, radon can become more concentrated inside a building.
Individuals working with asbestos are more likely to die of lung cancer, including squamous cell carcinoma of the lung. Asbestos exposure can occur in textile plants, areas that use insulation, shipyards, and mines.
Even though it is not clear how much exposure raises lung cancer risk, people who often smoke and are exposed to asbestos have a much greater risk.
Other workplace cancer-causing substances that can increase the risk of squamous cell carcinoma of the lungs include:
Radioactive ores including uranium
Other inhaled chemicals such as beryllium, arsenic, chromium and nickel compounds, coal products, and mustard gas
Diesel exhaust (diesel particulate matter [DPM])
In places with significant air pollution (congested roads and heavy industry), the risk of developing lung cancer increases slightly. Although this risk is far less than the risk caused by smoking, research still indicates around 5% of all deaths from lung cancer may result from outdoor air pollution.
Individuals who have had radiation therapy to the chest for other types of cancers are at a higher risk of developing different types of lung cancer, especially if they smoke. This includes people who have been treated for Hodgkin’s lymphoma or have received chest radiation after a mastectomy for breast cancer.
Those that had lung cancer in the past have a higher risk of developing another type of lung cancer. Additionally, children and siblings of those with lung cancer may have a slightly higher risk of developing lung cancer, especially if their relative was diagnosed young.
Depending on the spread of the squamous cell carcinoma, the type of treatment can include surgery, radiation therapy, chemotherapy, targeted therapy, immunotherapy, or a combination of these treatments.
Surgery for squamous cell carcinoma is often used when the cancer is in stage I, stage II, or occasionally, stage III. However, depending on the circumstances of the tumor, surgery may be combined with chemotherapy and radiation therapy.
Chemotherapy is a specific type of drug treatment that uses powerful chemicals to kill fast-growing cancer cells in the body. Chemotherapy can be used alone or combined with radiation therapy, either before or after lung cancer surgery. It may be combined with immunotherapy, which provides the greatest benefit to survival where cancer has spread.
Radiation therapy controls symptoms related to cancer spread and treats cancer itself. A combination of chemotherapy and radiation therapy is often used for stage III cancer.
Instead of trying to stop the cancer cells directly, immunotherapy trains the patient's immune system to recognize cancer cells to target and kill them. Today, there are four FDA-approved immunotherapy drugs for patients with squamous cell lung cancer. These drugs work by targeting and blocking the ‘braking’ mechanisms of the immune system so it can fight the cancer cells.
The five-year survival rate for squamous cell carcinoma of the lung can be 99% if doctors catch it quickly. There are no statistics for the later stages, but a doctor would provide an estimate based on the case. Immunotherapy has improved prognoses for patients with lung cancer, and ongoing clinical advancements may continue to lead to better outcomes.
Even though squamous cell lung carcinoma can develop for many reasons, you can significantly decrease your lung cancer risk by not smoking and avoiding secondhand smoke.
It is important to be aware that symptoms of this disease can differ depending on the stage, with most symptoms appearing when cancer has spread. Fortunately, there are various treatment options for squamous cell lung carcinoma, and the overall outlook improves the earlier a person receives a diagnosis.