What is cancer?
Cancer is the result of a mutation within the cell's DNA, that causes the mutated cell to multiply in an uncontrolled manner.
In a normal cell the DNA has informational instructions that control the reproduction of the cell. When a cell dies the surrounding cells are stimulated to duplicate and replaced the damaged or dead cell.
Then the surrounding cells release proteins that send a message to the DNA of the cell to stop reproducing.
In a mutated cell the DNA is damaged so that the message to stop reproducing is not obeyed. The cell continues to reproduce producing more and more copies of itself. Often the copies are increasingly more damaged and continue to reproduce, destroying healthy cells around them.
With the complexity of the information in the cells DNA mistakes happen constantly. Every body always have cancer cells present.The body's immune system normally destroys the damaged cells. When the immune system can not recognize or destroy the cancer cells then the disease of cancer occurs.
Cancer then is the multiplication of mutated or damaged cells. When the cells do not stop reproducing and reproduce faster than the immune system can kill them the disease of cancer occurs.