Cancer

Cancer

Cancers are thought to be a group of closely related diseases, and as such al cancers have certain characteristics in common. 

These include the following:

Hyperplasia

Hyperplasia is the uncontrolled reproduction of cells. Although the rate of reproduction among cancer cells is usually unchanged, they are not responsive to normal controls on cell numbers. As a result, cancer cells eventually give rise to large cell populations.

Anaplasia

The word anaplasia is used to describe the appearance of abnormalities in cellular structure. Typically, cancer cells resemble undifferentiated or primitive cells. That is, they fail to develop the specialized structure of the kind of cell they represent. Also they fail to function in expected ways.

Certain white blood cells, for example, normally function in resisting bacterial infections. When cells of this type become cancerous, they do not function effectively, and the cancer victim becomes more subject to infectious diseases. Cancer cells also are likely to form jumbled masses rather than becoming arranged in orderly groups like normal cells.

Metastasis

Metastasis has a tendency to spread. Normal cells are usually cohesive: i.e., they stick together in groups of similar kinds. Cancer cells often become detached from their cellular mass and may then be carried away from their place of origin and may establish new cancerous growths in other parts of the body. Metastasis is the characteristic most closely associated with the word malignant, which suggests a power to threaten life, and is often used to distinguish a cancerous growth from a non-cancerous(benign) one.

The cause of cancers remain largely unknown. There is, however, increasing evidence that the causes are complex. Among the factors that may be involved are exposure to various chemicals or to harmful radiation, virus infections, changes in DNA structure, or deficiencies in the body’s ability to resist disease. Actually, two or more of these factors may be needed to cause a cancer, or perhaps different kinds of cancers are caused by different factors or combinations of factors.

When untreated, cancer cells eventually accumulate in large numbers. They may damage normal cells by effectively competing with them for nutrients. At the same time, cancer cells may invade vital organs and interfere with their functions, obstruct important passageways, or penetrate blood vessels and cause internal bleeding.