Skip to main content
An official website of the United States government
Español

lung cancer

(lung KAN-ser)
Cancer that forms in tissues of the lung, usually in the cells lining air passages. The two main types are small cell lung cancer and non-small cell lung cancer. These types are diagnosed based on how the cells look under a microscope.
More Information
Respiratory system anatomy; drawing shows the right lung with the upper, middle, and lower lobes, the left lung with the upper and lower lobes, and the trachea, bronchi, lymph nodes, and diaphragm. An inset shows the bronchioles, alveoli, artery, and vein.Enlarge this image in new window
Anatomy of the respiratory system showing the trachea, the right and left lungs and their lobes, and the bronchi. The lymph nodes and the diaphragm are also shown. Oxygen is inhaled into the lungs and passes through the alveoli (the tiny air sacs at the end of the bronchioles) and into the bloodstream (see inset), where it travels to the tissues throughout the body.
Search NCI's Dictionary of Cancer Terms