Cancer is a generic term for about 100 different diseases that are characterized by uncontrolled cell growth. Genes tell specific cells when to be gin growing and how many cells to make. The information locked up in the genes regulate how tall an individual will be at maturity, the color of their hair and eyes, whether or not an individual will lose their hair at old age, and what sex an individual will be. The typical human is composed of approximately 30 trillion cells. Controlling the body's functions requires an unceasing collaboration between cells to ensure that each tissue maintains a size and architecture appropriate for the body's needs.
Cancer cells violate the natural scheme by following their own agenda for growth and proliferation.
In addition to uncontrolled growth, they migrate throughout the body and invade other tissues, destroying the ability of the healthy tissues to functio n. Death is often the result. It is known that the cells in a malignant tumor descended from a common ancestor cell. Further, the transformation of a healthy cell into a cancer cell is linked to changes in the genes. Mutations to a gene can perturb a cell, causing it to develop and grow uncontrollably. Excess exposure to radioactive substances is to be avoided because of the increased cancer risk such exposure creates.