Lung cancer is cancer that starts in the lungs.

The lungs are located in the chest. When you breathe, air goes through your nose, down your windpipe (trachea), and into the lungs, where it spreads through tubes called bronchi. Most lung cancer begins in the cells that line these tubes.

There are two main types of lung cancer:

• Non-small cell lung cancer (NSCLC) is the most common type of lung cancer.
• Small cell lung cancer makes up about 20% of all lung cancer cases.

If the lung cancer is made up of both types, it is called mixed small cell/large cell cancer.

If the cancer started somewhere else in the body and spread to the lungs, it is called metastatic cancer to the lung.

Cancer - lung

Lung cancer is the deadliest type of cancer for both men and women. Each year, more people die of lung cancer than of breast, colon, and prostate cancers combined.

Lung cancer is more common in older adults. It is rare in people under age 45.

Cigarette smoking is the leading cause of lung cancer.

The more cigarettes you smoke per day and the earlier you started smoking, the greater your risk for lung cancer. There is no evidence that smoking low-tar cigarettes lowers the risk.

However, lung cancer has occurred in people who have never smoked.

Secondhand smoke (breathing the smoke of others) increases your risk for lung cancer. According to the American Cancer Society, an estimated 3,000 nonsmoking adults will die each year from lung cancer related to breathing secondhand smoke.

The following may also increase your risk for lung cancer:

• Asbestos
• Exposure to cancer-causing chemicals such as uranium, beryllium, vinyl chloride, nickel chromates, coal products, mustard gas, chloromethyl ethers, gasoline, and diesel exhaust
• Family history of lung cancer
• High levels of air pollution
• High levels of arsenic in drinking water
• Radiation therapy to the lungs
• Radon gas

Early lung cancer may not cause any symptoms.

Symptoms depend on the type of cancer you have, but may include:

• Chest pain
• Cough that doesn't go away
• Coughing up blood
• Fatigue
• Losing weight without trying
• Loss of appetite
• Shortness of breath
• Wheezing

Other symptoms that may also occur with lung cancer, often in the late stages:

• Bone pain or tenderness
• Eyelid drooping
• Facial paralysis
• Hoarseness or changing voice
• Joint pain
• Nail problems
• Shoulder pain
• Swallowing difficulty
• Swelling of the face or arms
• Weakness

These symptoms can also be due to other, less serious conditions, so it is important to talk to your health care provider.

For more information, see:

• Non-small cell lung cancer
• Small cell lung cancer

Many times, lung cancer is found when an x-ray or CT scan is done for another reason.

For more information about the diagnosis of lung cancer, see:

• Non-small cell lung cancer
• Small cell lung cancer

For more information about the treatment of lung cancer, see:

• Non-small cell lung cancer
• Small cell lung cancer