Cancer occurs when cell division gets away from control and the timing of cell division involving a network of signals working together is under strict constraint and cells grow abnormally in the body. Mutations in one or more of the nodes in this network can trigger cancer due to genetic disposition or through revelation to some environmental factors. The unusual cell growth that brings about cancer is the result of damage to DNA - the substance inside all cells that directs cell behavior. By activities such as smoking etc or by genetics, injured DNA occurs and the body can repair this injured DNA, but cancer cells evade this process naturally
heart cancer pictures
