Cancer develops in our cells, the body’s basic unit of life. To
understand lung cancer, it is helpful to know how normal cells
become cancerous. 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 astray — cells keep dividing when new
cells are not needed. The mass of extra cells forms a growth or
tumor. These abnormal cells primarily originate when the lungs
are exposed to cancer causing substances (carcinogens), such as
those found in cigarette smoke, asbestos and silica dust. Tumors
can be benign or malignant. Benign lung tumors are not lung
cancer. They often can be removed and, in most cases, they do
not come back. Cells in benign tumors do not spread to other
parts of the body. Most important, benign tumors are rarely a
threat to life. Malignant lung tumors are lung cancer. Cells in
malignant tumors are abnormal and divide without control or
order. These cancer c