University of California, Los Angeles
School of Medicine Department of Ocnology

What is Cancer?

"Cancer" is used to describe a disease in which abnormal cells divide and multiply uncontrollably and invade other tissues. Cancer cells can spread throughout the body through the blood and lymph nodes.

There are many types of cancers. Most cancers are named for the organ of type of cell in which it started. For instance, when cancer originates in the breast, it is called breast cancer.

The body is made up of many types of cells. These cells grow and divide in a controlled way to produce more cells to keep the body healthy. When cells become old or damaged, they are replaced by new cells.

Sometimes the genetic material of a cell (DNA) can become damaged or changed, resulting in mutations that affect the normal cell growth process. When this happens, cells do not die when they should and new cells form when the body doesn’t need them. The extra cells may form a mass of tissue called a tumor. However, not all tumors are cancerous; tumors can be both benign or malignant.

• Benign tumors are not cancerous. They can often be removed and in most cases, they do not come back. These kinds of tumors do not spread to other parts of the body.

• Malignant tumors are cancerous. These cells can invade nearby tissue and spread to other parts of the body. When cancer cells spread to other parts of the body, it is called metastasis.

More Cancer Information:

What is Cancer?
Symptoms
Risk Factors
Tests
Common Side Effects of Cancer Therapy
Pain Management
Cancer Types