Lung cancer is cancer that forms in tissues of the lung, usually in the cells that line the air passages. It is the leading cause of cancer death in both men and women.

There are two main types: small cell lung cancer and non-small cell lung cancer. These two types grow differently and are treated differently. Non-small cell lung cancer is the more common type.

Anyone can develop lung cancer, but certain factors raise your risk of getting it:

• Smoking. This is the most important risk factor for lung cancer. Tobacco smoking causes about 9 out of 10 cases of lung cancer in men and about 8 out of 10 cases of lung cancer in women. The more years you smoke and the more cigarettes you smoke each day, the more your risk goes up. Your risk is also greater if you smoke a lot and drink alcohol every day or take beta carotene supplements. If you have quit smoking, your risk will be lower than if you had kept smoking. But you will still have a higher risk than people who never smoked.
• Secondhand smoke, which is the combination of the smoke that comes from a cigarette and the smoke breathed out by a smoker. When you breathe in secondhand smoke, you are exposed to the same cancer-causing agents as smokers, although in smaller amounts.
• A family history of lung cancer.
• Being exposed to asbestos, arsenic, chromium, beryllium, nickel, soot, or tar in the workplace.
• Being exposed to radiation, for example from:
  • Radiation therapy to the breast or chest
  • Radon in the home or workplace
  • Certain imaging tests such as CT scans
• HIV infection. Your risk is higher if you have HIV. However, smoking rates are higher in people who have HIV, so it's not clear whether the increased risk is from the HIV infection or from smoking.
• Air pollution. Studies show that living in areas with higher levels of air pollution increases your risk of lung cancer.

Lung cancer may not cause any signs or symptoms until the cancer is advanced. Sometimes the cancer is found during a chest x-ray done for another condition.

The symptoms of lung cancer may include:

• Chest pain or discomfort
• A cough that doesn't go away or gets worse over time
• Coughing up blood
• Trouble breathing
• Wheezing
• Hoarseness
• Loss of appetite
• Weight loss for no known reason
• Feeling very tired
• Trouble swallowing
• Swelling in the face and/or veins in the neck

To find out if you have lung cancer, your health care provider:

• Will take your medical history, which includes asking about your symptoms
• Will ask about your family history
• Will do a physical exam
• May order certain imaging tests, such as a chest x-ray or chest CT scan
• May order lab tests, including tests of your blood and sputum
• May do a procedure to take a biopsy of the lung

If you do have lung cancer, your provider will do other tests to find out if it has spread through the lungs, lymph nodes, and the rest of the body. This is called staging. Knowing the type and stage of lung cancer you have helps your provider decide what kind of treatment you need.

If you have small-cell lung cancer, your provider may also do genetic testing to look for certain gene changes (variants) in your cancer cells. The results of the testing may help guide treatment.

For most patients with lung cancer, current treatments do not cure the cancer.

Your treatment will depend on which type of lung cancer you have, how far it has spread, your overall health, and other factors. You may get more than one type of treatment.

The treatments for small cell lung cancer may include:

• Surgery.
• Chemotherapy.
• Radiation therapy.
• Immunotherapy.
• Laser therapy, which uses a laser beam to kill cancer cells.
• Endoscopic stent placement. An endoscope is a thin, tube-like instrument used to look at tissues inside the body. It may be used to put in a device called a stent. The stent helps to open an airway that has been blocked by abnormal tissue.

The treatments for non-small cell lung cancer may include:

• Surgery.
• Radiation therapy.
• Chemotherapy.
• Targeted therapy, which uses drugs or other substances that attack specific cancer cells with less harm to normal cells.
• Immunotherapy.
• Laser therapy.
• Photodynamic therapy (PDT), which uses a medicine and a certain type of laser light to kill cancer cells.
• Cryosurgery, which uses an instrument to freeze and destroy abnormal tissue.
• Electrocautery, a treatment that uses a probe or needle heated by an electric current to destroy abnormal tissue.

Avoiding the risk factors may help prevent lung cancer. For example, you can:

• Quit smoking. And if you don't smoke, don't start.
• Lower your exposure to hazardous substances at work.
• Lower your exposure to radon. Radon tests can show whether your home has high levels of radon. You can buy a test kit yourself or hire a professional to do the test.

NIH: National Cancer Institute