Bhjhuu

Cancer
 Known medically as a malignant neoplasm,  is a term used for diseases in which abnormal cells divide without control and are able to invade other tissues. Cancer cells can spread to otherparts of the body through the blood and lymph systems.
Cancer is not just one disease but many diseases. There are more than 100 different types of cancer. Most cancers are named for the organ or type ofcell in which they start.
Cancer types can be grouped into broader categories. The main categories of cancer include:
* Carcinoma - cancer that begins in the skin or in tissues that line or coverinternal organs. There are a number of subtypes of carcinoma, including adenocarcinoma, basal cell carcinoma, squamous cell carcinoma, and transitional cell carcinoma.
* Sarcoma - cancer thatbegins in bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue.
* Leukemia - cancer that starts in blood-forming tissue such as the bone marrow and causes large numbersof abnormal blood cells to be produced and enter the blood.
* Lymphoma and myeloma - cancers that begin in the cells of the immune system.
* Central nervous system cancers - cancers that beginin the tissues of the brain and spinal cord.
Origins of Cancer
All cancers begin in cells, the body's basic unit of life. To understand cancer, it's helpful to know what happens when normal cellsbecome cancer cells.
The body is made up of many types of cells. These cells grow and divide in a controlled way to produce more cells as they are needed to keep the body healthy. When cells become old ordamaged, they die and are replaced with new cells.
However, sometimes this orderly process goes wrong. The genetic material (DNA) of a cell can become damaged or changed, producing mutations thataffect normal cell growth and division. When this happens, cells do not die when they should and new cells form when the body does not need them. The extra cells may form a mass of tissue called...