The body is made up of many types of cells. Normally, cells grow, divide, and produce more cells as needed to keep the body healthy and functioning properly. Sometimes, however, the process goes wrong and cells become abnormal, forming more cells in an uncontrolled way. These extra cells form a mass of tissue, called a growth or tumor. Tumors can be benign, which means not cancerous, or malignant, which means cancerous. Lung cancer occurs when a tumor forms in the tissue of the lung.Lung cancer is the leading cause of cancer death in men and women in the United States. Experts estimate that there will be 215,020 new cases of lung cancer in 2008-- 114,690 cases in men and 100,330 cases in women. 161,840 Americans are expected to die of the disease 90,810 men and 71,030 women. Lung cancer occurs most often between the ages of 55 and 65.
There are two major types of lung cancer -- non-small cell lung cancer and small cell lung cancer. Each type of lung cancer grows and spreads in different ways, and each is treated differently. Non-small cell lung cancer is more common than small cell lung cancer. Small cell lung cancer, sometimes called oat cell cancer, grows more quickly and is more likely to spread to other organs in the body.
Lung cancer may spread to the lymph nodes or other tissues in the chest, including the lung opposite to where it originated. It may also spread to other organs of the body, such as the bones, brain, or liver. When cancer spreads from its original location in the lung to another part of the body such as the brain, it is called metastatic lung cancer, not brain cancer. Doctors sometimes call this distant disease.
Lung cancer would occur much less often if people did not smoke. The good news is that smoking is not as popular as it used to be. In 1965 about 42 percent of all adults smoked, but by 2008 only 21 percent did. Also, there has been a sharp drop in lung cancer deaths among men, mainly because fewer men are smoking.
The bad news is that smoking rates, which were dropping, have stopped declining in recent years. Smoking by young adults actually increased by 73 percent in the 1990s but has shown a downturn or leveling off in the past few years. Also, more women are getting lung cancer than ever before and more are dying from it, mainly because more young women are smoking -- however, this trend is also starting to reverse itself. Many smoking education programs now focus more directly on women and young people who smoke.