Lung Cancer

Lung cancer is a cancer that starts in the lungs. The lungs are a pair of cone-shaped organs inside the chest that allow you to breathe. The lungs bring oxygen into the body when you breathe in and send carbon dioxide out of the body when you breathe out.

Cigarette smoking causes most lung cancers. The more cigarettes you smoke per day and the earlier you started smoking, the greater your risk of lung cancer. High levels of pollution, radiation, and asbestos exposure may also increase your risk of developing lung cancer.

Lung cancer is one of the most common cancers in the world. It is the leading cause of cancer death in men and women in the United States. Lung cancer accounts for about 27% of all cancer deaths, and lung cancer claims more lives each year than colon, prostate, ovarian and breast cancers combined.

The 2 main types of lung cancer are non-small cell lung cancer and small cell lung cancer. The types of cancer are based on the way the cells look under a microscope. Non-small cell lung cancer is much more common than small cell lung cancer. Non-small cell lung cancer is an umbrella term for several types of lung cancers that behave in a similar way. Non-small cell lung cancers include squamous cell carcinoma, adenocarcinoma and large cell carcinoma. Small cell lung cancer occurs almost exclusively in heavy smokers and is less common than non-small cell lung cancer.

Treatment for lung cancer depends on the type, stage, and how advanced it is. Treatments include surgery, chemotherapy, radiation therapy, and targeted therapy. For most patients with lung cancer, current treatments do not cure the cancer.

Smoking causes the majority of lung cancers — both in smokers and in people exposed to secondhand smoke. Smoking causes lung cancer by damaging the cells that line the lungs.

Lung cancer also occurs in people who never smoked and in those who never had prolonged exposure to secondhand smoke. In these cases, there may be no clear cause of lung cancer.

In general, cancer occurs when cells in your liver develop errors (mutations) in their DNA. The errors make cells grow and divide out of control. The accumulating abnormal cells form a tumor in the lung that can grow to invade nearby structures and spread to other parts of the body.

Factors that increase your risk for lung cancer include:

• smoking
• exposure to secondhand smoke
• exposure to radon gas
• exposure to asbestos and other carcinogens
• family history of lung cancer

See your doctor for a cough that will not go away or worsens, coughing up blood, chest pain, or unexplained weight loss, and ask about screening if you have a smoking history. Seek emergency care for coughing up a large amount of blood or severe shortness of breath.