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How Does a Normal Cell Become Cancer?

Normal body cells grow, divide, and die in an orderly fashion. During the early years of a person’s life, normal cells divide more quickly until the person becomes an adult. After that, cells in most parts of the body divide only to replace worn-out or dying cells and to repair injuries.

Cancer cells develop because of damage to DNA. DNA is in every cell and directs all of the cell’s activities. Most of the time when DNA becomes damaged, either the cell dies or is able to repair the DNA. In cancer cells, the damaged DNA is not repaired. People can inherit damaged DNA, which accounts for inherited cancers. Many times though, a person’s DNA becomes damaged by things in the environment, such as chemicals, viruses, tobacco smoke, or too much sunlight.

Benign Tumors

Benign tumors are not cancer. In fact, they are rarely life threatening. In most cases, when benign tumors are removed, they do not grow back. They do not invade the surrounding tissues, and they do not spread to other parts of the body.

Malignant Tumors

On the other hand, malignant tumors are cancerous. They are typically more serious than benign tumors and can be life threatening. Sometimes, malignant tumors can be removed, but they may later return in either the same location or somewhere else in the body. They can invade nearby tissue and damage nearby organs. They can spread, or metastasize, to other parts of the body. They can spread by breaking away from their primary site and enter the bloodstream or lymphatic system. Once they have spread to other parts of the body, they can attach to organs or bone and form new tumors.


The spread of cancer cells is called metastasis. This occurs when some of the cancer cells break away and travel through the blood stream or the lymph system. If the cancer spreads to another area of the body, it is still the same cancer. For example, if prostate cancer cells metastasize to bone, it is not bone cancer. They are still prostate cancer cells and, therefore, the treatment is still for prostate cancer. To determine if your cancer has spread, your physician may order additional diagnostic tests.