What Is Cancer?
According to the National Cancer Institute, cancer is "a term for diseases in which abnormal cells divide without control."
Typically cancer occurs in the form of a tumor
, but some cancers, like leukemia
, occur inside the blood or the organs formed by blood.
What Causes Cancer?
Scientists know that certain things increase the risk of cancer. For example, smoking may cause lung, mouth and other cancers, and the sun's harmful rays may cause skin cancer. However, what exactly causes cancer is unknown.
Scientists do know that abnormal cell division causes cancer cells to develop. Cells in the body normally go through the following process:
- They grow and divide to form other cells the body needs.
- They get old and die.
- The dead cells get replaced by new cells.
However, sometimes this process of cell growth, division and death doesn't happen as planned. In the case of cancer, old cells do not die, and new cells develop, even though the body doesn't need them. This abnormal cell division causes cancer to occur.
Find out what might put you at risk for certain types of cancer by visiting the following pages in this section:
