The Facts

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. The majority of 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.

There are an estimated 175,000 new cases of lung cancer lung cancer diagnosed in the United States each year and rates for women are only half as high as the rates for men but are about twice as high as their rates in 1975.

Causes

Smoking is the main risk factor for lung cancer and is responsible for more than 80% of lung cancers. The longer you have smoked and the more you smoke, the more likely you are to get lung cancer. If you stop smoking before a cancer develops, lung tissue that has been damaged by smoking will start to repair. An ex-smoker's risk will not be as low as that of a person who never smoked, but over time, it will fall. Cigar smoking and pipe smoking are almost as likely to cause lung cancer as cigarette smoking is.

Even second-hand smoke, the kind inhaled from nearby smokers, can cause lung cancer. Non-smokers who are married to smokers have a 30% greater risk of developing lung cancer than spouses of non-smokers. Recently, a woman who worked in a smoking environment, but never actually smoked herself, developed lung cancer and was able to claim it as a work-related injury.

Living in an environment with high air pollution or working with radioactive minerals or asbestos can also increase the risk of cancer. Research has helped us to understand how these risk factors produce certain changes in the DNA of lung cells. These changes cause the cells to grow abnormally and form cancers. DNA is the genetic material that carries the instructions for nearly everything our cells do. Some genes (parts of our DNA) contain instructions for controlling when cells grow and divide. The risk factors discussed earlier can trigger changes, also called mutations, in these genes that result in cancer. A risk for some types of cancer (e.g., breast, ovarian, colorectal, and several others) can be inherited from parents. However, inherited gene mutations are not thought to be a cause of very many lung cancers.