Cancer (medicine), any of more than 100 diseases characterized by excessive, uncontrolled growth of abnormal cells, which invade and destroy other tissues. Cancer develops in almost any organ or tissue of the body, but certain types of cancer are more lethal than others. Cancer is the leading cause of death in Canada and second only to heart disease in the United States.
Sixty percent of people diagnosed with cancer now survive more than five years. Between 1990 and 1995 cancer incidence and death rates dropped for the first time in 20 years. In 1998 the ACS, the NCI, and the Centers for Disease Control and Prevention (CDC) confirmed that cancer rates are still on the decline. In the past 40 years, the death rate from cancer in children has dropped 62 percent. These improved cancer statistics are due in part to behavioral and lifestyle changes, but equal credit goes to the advances in cancer research that have taken place in the last three decades.
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