Cancer

CANCER

Cancer is the name given to a set of related diseases. In all cancers, some of the body's cells begin to divide without stopping and spread to surrounding tissues.

Cancer can start almost anywhere in the body, which is made up of trillions of cells. Normally, human cells grow and divide to form new cells as the body needs them. When normal cells grow old or get damaged, they die, and new cells replace.

However, in cancer, this orderly process goes wrong. As the cells become more and more abnormal, old or damaged cells survive when they should die, and new cells form when not needed. These extra cells can divide without interruption and can form masses called tumors.

Many cancers are solid tumors, which are masses of tissue. Blood cancers such as leukemias, generally do not form solid tumors.

Cancerous tumors are malignant, meaning it can spread to nearby tissues or can invade. In addition, these tumors to grow, some cancer cells can break off and move to distant sites in the body through the circulatory system or lymphatic system and form new tumors away from the original tumor.

Unlike malignant tumors, benign tumors do not spread to nearby tissues and not invade. However, sometimes benign tumors can be quite large. When removed, usually do not grow back, while other malignant tumors sometimes grow back. Unlike most benign tumors elsewhere in the body, benign brain tumors can be life threatening.

Differences between cancer cells and normal cells

Cancer cells differ from normal cells in many ways that allow them to grow uncontrollably and become invasive. One important difference is that cancer cells are less specialized than normal cells. This means that, while normal cells mature into many different cell types with specific functions, cancer cells do not. This is a reason that, unlike normal cells, cancer cells continue dividing without stopping.

Also, cancer cells can ignore the signals that normally tell cells to stop dividing or starting a process known as programmed cell death, or apoptosis, which uses the body to get rid of cells that are not necessary.

Cancer cells may have the ability to influence normal cells and molecules in blood vessels that surround and feed the cells of a tumor-area is known as the microenvironment. For example, cancer cells can induce the nearby normal cells forming blood vessels that supply oxygen and nutrients needed to grow tumors. These blood vessels also remove waste products from the tumors.

Cancer cells often are also able to evade the immune system, a network of organs, tissue and specialized cells that protect the body against infections and other diseases. Although ordinarily the body's immune system eliminates damaged or abnormal cells, some cancer cells are able to "hide" from the immune system.

Tumors can also use the immune system to stay alive and grow. For example, with the help of certain immune system cells that ordinarily prevents uncontrolled immune response, cancer cells may in fact cause the immune system does not destroy cancer cells.

How cancer appears

Cancer is a disease that is genetically, is caused by changes in genes that control how our cells, especially the way they grow and divide work.

The genetic changes that cause cancer can be inherited from parents. They can also happen in the life of a person as a result of errors that occur when cells divide or DNA damage caused by some environmental exposures. Environmental exposures are cancer-causing substances, such as chemicals in the smoke of snuff and radiation such as ultraviolet rays. (Our page Causes and risk factors for cancer have more information).

Cancer each person has a unique combination of genetic changes. As cancer continues to grow, additional changes will occur. Even within each tumor, different cells may have different genetic changes.

Overall, cancer cells are more genetic changes such as mutations in the DNA than normal cells. Some of these changes may not be related to cancer; They may be the result of cancer and not its cause.