Normal cells in the body grow, divide, and die. Cancer is the name for abnormal cells that grow and divide, but don't die like they should. When the DNA in cells is damaged and the body can't repair it, cancer happens. This damage can be inherited, which is why doctors ask about family history. Often, the damage is caused by exposure to something in the environment, like smoking. Most cancer cells grow in groups called tumors. Some, like leukemia, grow in the blood and the organs that make blood. Doctors choose a treatment based on where and how the cells are growing.
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