More men die of lung cancer than any other cancer. For women, it's the second largest killer, after breast cancer. It usually occurs between the ages of 65 and 75.

Most lung cancers start in the bronchi, the airways leading to the lungs. There are different types of lung cancer. The most common is called squamous cell carcinoma. Other types of lung cancer are small cell carcinoma or oat cell carcinoma, adenocarcinoma, and large cell carcinoma.

Each type grows at a different rate and responds differently to treatment. Except for adenocarcinoma, most lung cancers are related to smoking. Cancer that has spread from other parts of the body to the lungs is also common.

Causes and risk factors

Smoking is responsible for more than 80% of lung cancers. It is estimated that smokers are at 10 to 30 times as high a risk for lung cancer as the general population. Cigar smoking and pipe smoking are almost as likely to cause lung cancer as cigarette smoking is. Even secondhand smoke, the kind inhaled from nearby smokers, can cause lung cancer.

Living in an environment with high air pollution or working with radioactive minerals or asbestos can also increase the risk of cancer. These risk factors produce certain changes in the DNA of lung cells, causing the cells to grow abnormally and form cancers.

Symptoms and complications

The first and most common symptom of lung cancer is a cough.

Other symptoms include:

  • coughing up blood
  • wheezing
  • chest pain
  • pneumonia (symptoms include cough, fever, chest pain, and shortness of breath)
  • loss of appetite, weakness, and weight loss

Lung cancer can spread to parts of the body near the lungs or to other parts of the body such as the liver, brain, and bones, causing pain and other complications, such as heart failure, difficulty breathing, and nerve damage. Some cancers also release hormones that can affect the body's metabolism.