What is Cancer
Cancer is a term used for diseases in which abnormal cells divide without control and are able to invade other tissues.
Body cells normally follow an orderly growth division and destruction. Early in a person’s life, normal cells divide more rapidly, ’till the person becomes an adult. Later normal cells in most tissues divide evenly to replace naturally lost cells or to repair injuries.
Cancer is named after the part of the body where it began, and by its appearance under a microscope. The cell collections form tumors and lumps that may press, invade and destroy adjoining normal tissue. Some cells from such a tumor can travel through blood stream, or the lymph system to other areas of the body. Here they may settle and form secondary tumors. This new focus is called metastasis. This still bears the name of the original part of the body where it started. Breast cancer spreading to the lungs is still called breast cancer metastasis.
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 cover internal organs.
- Sarcoma – cancer that begins 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 numbers of 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 begin in the tissues of the brain and spinal cord.