Definition of Tumor:

A tumor is an abnormal growth of body tissue. Tumors can be cancerous (malignant) or non-cancerous (benign).

Causes, incidence, and risk factors:

In general, tumors appear to occur when there is a problem with the dividing of cells in the body. Typically, the division of cells in the body is strictly controlled. New cells are created to replace older ones or to perform new functions. Cells that are damaged or no longer needed die to make room for healthy replacements.

If the balance of cell division and death is disturbed, a tumor may form.

Problems with the body's immune system can lead to tumors. Tobacco causes more deaths from cancer than any other environmental substance. Other causes include obesity, inactivity (sedentary lifestyle), excessive alcohol consumption, radiation, genetic problems, excessive sunlight exposure, benzene, and a number of other chemicals and toxins.

Certain viruses can play a role in the development of tumors, such as cervical cancer and hepatocellular carcinoma.

Some tumors are more common in one sex than the other, some are more common among children or the elderly, and some vary with diet, environment, and your family history.