Cancer is not one disease but is a group of more than 200 different diseases in which there is an abnormal growth of cells, causing the cells to grow into masses of tissue called tumors. Death occurs when vital tissues and organs are so damaged by the invasion of the cancer that they can no longer function. More than one million people will be diagnosed with cancer this year and more than half a million people will die of the disease. There has been a steady increase in the cancer death rate in the u.s. However, death rates due to other major cancers have leveled off or declined in the past 50 years.
Cancer cells attack healthy tissue and never stop multiplying.
Cancer behaves differently in different people, depending on the type of cancer involved. It can occur at any age, but is more likely to occur in older people, usually age 55 or older. Cancer can also occur in children and, in fact, is the second leading cause of death in children between the ages of 1 and 15. Cancer can be caused by environmental factors, which are external to the body, or internal factors from within your body. Environmental factors that can cause cancer include exposure to certain chemicals, such as benzene and asbestos.