What are Cancer Cells?
Cancer begins in cells, the building blocks that make up tissues. Tissues make up the organs of the body. Normal, healthy cells grow and divide to form new cells as the body needs them. When normal cells grow old or become damaged, they die, and new cells take their place. Sometimes, this orderly process goes wrong. New cells form when the body does not need them, and old or damaged cells do not die as they should. The build-up of extra cells often forms a mass of tissue called a growth or tumor. Tumor cells can be benign (not cancer) or malignant (cancer).
Cancer describes any of a group of diseases which are characterized by the uncontrolled growth of cells that are destructive to tissues and organs in the body, and can lead to death. Cancer cells form when normal cells become damaged and then multiply. It is not uncommon for a cell to form abnormally or become damaged, but in most cases the cell simply self-destructs in a process called apoptosis. Cancer cells appear to the body’s immune system to be normal cells, therefore the body’s defenses will not attack them. Most cancer cells multiply and stay localized, at least at first, forming a tumor, with one notable exception to this rule being leukemia. Not all tumors are cancerous, however. Benign tumors are growths that can share certain characteristics with cancerous tumors, but are self-limiting and non-destructive. They mostly do not come back after they are removed. Malignant or cancerous tumors form as a result of a mutation or other damage to the genetic material of a normal cell
