A disease in which cells of the body begin to divide out of control, rather than dying after a normal lifecycle. Cancer can occur in any tissue of the body and usually results in tumors that replace normal tissue and can complicate normal bodily functions.
Cancerous cells can travel to other parts of the body through the bloodstream or nymph vessels. This process is called metastasis.
Although the specific causes of many types of cancer are still unknown, it is often found to be caused by damage to cellular DNA which can be the result of exposure to chemicals or radiation. Damaged DNA can be inherited and cause inherited forms of cancer in affected progeny.
Different forms of cancer occuring in different tissues or organs, are named according to their origin and behave in a unique fashion, with varying growth rates and response to treatment. According to WHO, cancer is one of the leading causes of death in the world. However, many cancers can be prevented, or detected early and treated.