Cancer is not a new disease as is wrongly believed. However, these days its incidence is on the rise. At present about 20 to 25% of the human population in the world die of cancer and it is feared that in future it might become the greatest enemy of mankind.
Cancer is uncontrolled division of cells in the body. Any part of the body — skin, lungs, brain, bone marrow, ovary or stomach can become cancerous.
Normally, division of every cell is regulated for proper development and functioning. When cells loose this control, repeated cell division leads to a mass of abnormal cells — called tumor. A tumor does not have any function in body. Instead, wherever it starts due to rapid growth, it occupies a lot of space and pushes aside the tissues and organs around it. It draws their nutrients, and thus obstructs their vital function.
Tumors are of two types, benign and malignant. Benign tumors multiply slowly and are confined to a site. Cysts, moles, warts and polyps are benign tumors. But there is a risk that they may turn into malignant forms. Malignant tumors multiply rapidly and later some of the cells may detach from them, migrate into other vital organs via blood stream, and form new tumors there. This stage is called metastasis or secondary stage.
Cancer does not develop abruptly. It is the cumulative result of the effects of an agent on the body for several years or decades. Many risk factors such as radiation, chemicals in the environment, genetic predisposition, nutritional factors, immunological deficiencies, stress and negative mental state may induce or contribute to the development of cancer. It may also be induced by some viruses. Only 20 to 40% of all cancers are caused by hazardous conditions at the work place and other environmental pollutants. The rest are the result of natural cellular changes.
There are four categories of cancer as described below:
The cancers originating from skin, membranes around glands. nerves, breasts, lining of respiratory, urinary and digestive tracts.
Cancers originating from connective tissues, bones, muscles, fat and blood vessels.
Cancer of the organs and tissues, lymph glands bone marrow, etc. that form blood cells, causing an over production of immature white blood cells.
Cancers similar to leukemia leading to abnormal production of white blood cells by the spleen and lymph system.