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Conditions InDepth: Lung Cancer

Lung cancer is a disease in which cancer cells grow in the lungs.

Lung Cancer
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Lung cancer occurs when cells in the lung divide without control or order. Normally, cells divide in a regulated manner. If cells keep dividing uncontrollably when new cells are not needed, a mass of tissue forms, called a growth or tumor. The term cancer refers to malignant tumors, which can invade nearby tissues and can spread to other parts of the body. A benign tumor does not invade or spread.

Lung cancers that start in the lungs are divided into 2 types:

  • Non-small cell —This type generally grows and spreads more slowly. Non-small cell lung cancer accounts for the majority of the lung cancer cases that are diagnosed each year in the United States. The most common types of non-small cell lung cancer are squamous cell cancer and adenocarcinoma.
  • Small cell—This type generally grows more quickly. It is more likely to spread to other parts of the body.

Most cases of lung cancer are associated with tobacco use, such as:

  • First- or second-hand cigarette smoke
  • Pipe or cigar smoking, chewing tobacco

While most cases of lung cancer are due to smoking, a percentage of people with lung cancer have never smoked, nor have they been exposed to secondhand smoke. Lung cancer is the leading cause of death from cancer in the United States.

What are the risk factors for lung cancer?What are the symptoms of lung cancer?How is lung cancer diagnosed?What are the treatments for lung cancer?Are there screening tests for lung cancer?How can I reduce my risk of lung cancer?What questions should I ask my doctor?What is it like to live with lung cancer?Where can I get more information about lung cancer?

Revision Information

  • General information about non-small cell lung cancer. National Cancer Institute website. Available at: Accessed September 28, 2012.

  • Lung cancer (non-small cell) overview. American Cancer Society website. Available at: Updated February 23, 2012. Accessed September 28, 2012.

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