Lung cancer is the growth of abnormal cells in one or both lungs. These cells can multiply rapidly and turn into tumors that interfere with the function of the lungs and, eventually, spread to other parts of the body.

Lung cancer is the second most common kind of cancer diagnosed in North America, and accounts for nearly a third of all cancer deaths. Most people who get lung cancer were cigarette smokers, but non-smokers get it too. Exposure to radon, asbestos, and secondhand smoke are also risk factors. In some cases, there is no known cause.

One of the challenging aspects of lung cancer is that it may be years before symptoms emerge. By the time it’s diagnosed, about half the patients have cancer that’s already spread outside the lungs.

Common signs and symptoms of lung cancer include:

• A cough that doesn’t go away and gets worse over time
• Constant chest pain
• Coughing up blood
• Shortness of breath, wheezing or hoarseness
• Repeated problems with pneumonia or bronchitis
• Swelling of the neck and face
• Loss of appetite or weight loss
• Fatigue

Cancers that begin in the lungs are divided into two major types — small cell lung cancer and non-small cell cancer. The two types are distinguished by how the cancer cells look under a microscope. Each type of lung cancer grows and spreads differently and calls for different treatment.

Non-small cell lung cancer is more common and generally grows more slowly. There are four main types of this cancer. They are named for the cells in which the cancer develops:

• Squamous cell carcinoma
• Adenocarcinoma
• Bronchoalveolar carcinoma
• Large cell carcinoma

Small cell lung cancer, sometimes called oat cell cancer, is less common. This type of lung cancer grows more quickly and is more likely to spread to other organs.

Treatment for lung cancer depends on the cancer’s specific cell type, how far it has spread, and the patient’s performance status. Common treatments include surgery, chemotherapy, and radiation therapy.