Understanding Lung Cancer

What is Lung Cancer?

Lung cancer is a malignant tumor in the lungs.  This means that the abnormal cells of the tumor grow without order or control.  They destroy the healthy lung tissue around them.  Lung cancer can spread to other parts of the body.  Sometimes other types of cancer can spread to the lungs.  This type of tumor is not lung cancer.  The information here is about lung tissue cells that are abnormal and have become lung cancer.

There are two major types of lung cancer: small cell lung cancer and non-small cell lung cancer.  Non-small cell lung cancer is the more common.  It makes up about 80 percent of lung cancer cases.  This type of cancer usually grows and spreads to other parts of the body more slowly than small cell lung cancer does.

Why is Lung Cancer so Serious?

One reason lung cancer is such a killer is that it is hard to detect in its early stages.  It may take years for the lung cancer to grow, and early on there are usually no symptoms.  By the time the patient starts to notice symptoms, the cancer is often advanced.  Researchers are working hard to develop tests that can detect lung cancer in its early stages, when it can be treated more successfully.  Researchers are also seeking new treatments to increase the survival time and even cure lung cancer.

What Causes Lung Cancer?

Smoking is the number one cause of lung cancer.  It causes about 87 percent of lung cancer cases.  Tobacco smoke contains many chemicals that are known to cause cancer.  And smokers are not the only ones affected.  Nonsmokers can breathe in secondhand smoke and get lung cancer or other illnesses.

Radon exposure is the second leading cause of lung cancer.  Radon is a colorless, odorless radioactive gas that occurs naturally in soil.  It comes up through the soil and enters buildings through small gaps and cracks.  One out of every 15 homes in the U.S. has a radon problem.

Industrial exposures pose a lung cancer risk.  Working with certain hazardous materials, such as asbestos, uranium, arsenic, cadmium, chromium, nickel, and some petroleum products is especially dangerous.

Genetic factors also play a role in the likelihood that someone gets lung cancer.  Mutations in several genes have been linked to lung cancer, suggesting the disease has a genetic component.  So a family history of lung cancer may indicate a higher risk of developing the disease.

A small portion of lung cancers occur in people with no apparent exposure risk for the disease. Lung cancer in people who have never smoked is a major public health problem and continued research is needed. Women, compared to men, appear to have higher rates of lung cancer that is not linked to smoking.


Early detection of lung cancer can increase survival rates. Call the Lung Helpline at 1-800-LUNGUSA or talk to your doctor about lung cancer screening.