Lung Cancer Health Center

Lung cancer is one of the deadliest forms of cancer found in the United States. While tobacco smoking remains the primary cause of the disease, anyone can develop lung cancer – even people who have never smoked.

Your lungs are a pair of large organs in your chest. They are part of your respiratory system. Air enters your body through your nose or mouth. It passes through your windpipe (trachea), then through each bronchus before going into your lungs.

Cancer begins in cells, the building blocks that make up tissues. Tissues make up the organs of the body.

Normal, healthy cells grow and divide to form new cells as the body needs them. When normal cells grow old or become damaged, they die, and new cells take their place.

Sometimes, this orderly process goes wrong; new cells form when the body does not need them, and old or damaged cells do not die as they should. This build-up of extra cells often forms a mass of tissue called a growth or tumor.

Tumor cells can be benign (not cancer) or malignant (cancer). Benign tumor cells are usually not as harmful as malignant tumor cells.

Cancer cells spread by breaking away from the original tumor. They enter blood vessels or lymph vessels, which branch into all the tissues of the body. The cancer cells attach to other organs and form new tumors that may damage those organs. The spread of cancer is called metastasis.

Review Date: 
March 22, 2012
Last Updated:
November 4, 2014