Cancer is a very common disease, approximately one out of every two American men and one out of every three American women will have some type of cancer at some point during the course of their life. Cancer is more common in the elderly and 77 percent of cancers occur in people above age 55 or older. Cancer is also common in children. Cancer incidence is said to have two peaks once during early childhood and then during late years in life. No age period is completely exempted from development of cancers. Some cancers occur predominantly in the elderly, other types occur in children, Cancer occurs in all ethnic races, however the cancer rates and rates of specific cancer types may vary from group to group. Late stages of cancer may be incurable in most cases, but with the advancement of medicine, more and more cancers are becoming curable. Cancer may be curable if detected early in the course of the disease. Millions of people are living today with cancer or as cancer survivors. Early detection of cancer is very important because the generally earlier the cancer is detected higher the chance for cure.
All living things are made up of cells. Cells are the basic living units. Some living things like amoeba may have one cell only while a complex animal like a cat may have billions of cells in the body. Many cells divide to produce daughter cells. This is required for the replacement of cells lost during the course of life. The process of cell division is a very tightly controlled process and occurs in the body only to the extent needed in any particular situation. During the process of cell division one cell may acquire some genetic mutation that would alter the cell division control mechanisms of that cell. This altered cell no longer listens to the control signals for cell division and may continue to divide and multiply. This uncontrolled cell division and growth ultimately results in cancer.