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Lung Cancer Screening (PDQ®)

General Information About Lung Cancer

Lung cancer is a disease in which malignant (cancer) cells form in the tissues of the lung.

The lungs are a pair of cone-shaped breathing organs inside the chest. The lungs bring oxygen into the body when breathing in and send carbon dioxide out of the body when breathing out. Each lung has sections called lobes. The left lung has two lobes. The right lung, which is slightly larger, has three. A thin membrane called the pleura surrounds the lungs. Two tubes called bronchi lead from the trachea (windpipe) to the right and left lungs. The bronchi are sometimes involved in lung cancer. Small tubes called bronchioles and tiny air sacs called alveoli make up the inside of the lungs.

Respiratory anatomy; drawing shows right lung with upper, middle, and lower lobes; left lung with upper and lower lobes; and the trachea, bronchi, lymph nodes, and diaphragm. Inset shows bronchioles, alveoli, artery, and vein.
Anatomy of the respiratory system, showing the trachea and both lungs and their lobes and airways. Lymph nodes and the diaphragm are also shown. Oxygen is inhaled into the lungs and passes through the thin membranes of the alveoli and into the bloodstream (see inset).

There are two types of lung cancer: small cell lung cancer and non-small cell lung cancer.

See the following PDQ summaries for more information about lung cancer:

Lung cancer is the leading cause of cancer death in the United States.

Lung cancer is the third most common type of non-skin cancer in the United States. Lung cancer is the leading cause of cancer death in men and in women.

Different factors increase or decrease the risk of lung cancer.

Anything that increases your chance of getting a disease is called a risk factor. Anything that decreases your chance of getting a disease is called a protective factor.

For information about risk factors and protective factors for lung cancer, see the PDQ summary on Lung Cancer Prevention.

  • Updated: April 27, 2015