1.2 How Cancer Starts
All cancers begin in cells, the body's basic unit of life. To
understand cancer, it's helpful to know what happens when
normal cells become cancer cells. The body is made up of
many types of cells. These cells grow and divide in a
controlled way to produce more cells as they are needed to
keep the body healthy. When cells become old or damaged,
they die and are replaced with new cells. However,
sometimes this orderly process goes wrong. The genetic
material (DNA) of a cell can become damaged or changed,
producing mutations that affect normal cell growth and
division. When this happens, cells do not die when they
should and new cells form when the body does not need
them. The extra cells may form a mass of tissue called a
tumor. The effect on DNA is called nano effect.