About Cancer

What is Cancer?

Definition

Cancer is the uncontrolled growth of abnormal cells in the body. Cancerous cells are also called malignant cells.

Alternative Names

Carcinoma; Malignant tumor

Causes, Incidence, and Risk Factors

Cells are the building blocks of living things. Cancer grows out of normal cells in the body. Normal cells multiply when the body needs them and die when the body doesn't need them. Cancer appears to occur when the growth of cells in the body is out of control and cells divide too quickly. It can also occur when cells “forget” how to die.

There are many different kinds of cancers. Cancer can develop in almost any organ or tissue, such as the lung, colon, breast, skin, bones, or nerve tissue.

There are many causes of cancers, such as radiation and tobacco; however, the cause of many cancers remains unknown.

The three most common cancers in men in the United States are:

• Prostate cancer
• Lung cancer
• Colon cancer

In women in the United States, the three most common cancers are:

• Breast cancer
• Colon cancer
• Lung cancer

Click here to read about some other types of cancer.