Cancer is a common name for a group of diseases characterised by uncontrolled proliferation of abnormal cells. Cell division is the mainstay of human life. Human body is made up of several organs like brain, lung, liver, stomach etc. and each organ is made up of cells. Organs and tissues are constituted by cells characteristic of that organ. Cells divide for growth of an organ, for repairing tissue damage and to maintain functions of the organ. The divided cells are the exact replica of the parent cell. Sometimes due to some faulty mechanism or due to factors which are unknown yet, the divided cells are abnormal i.e., their structure is not the same as that of its parent cells. They cannot discharge the functions like the normal cells but requires the same food as the normal cells. These cells start dividing and a large number of abnormal cells are produced. As a result of the proliferation of abnormal cells the body organs do not function normally and the persons nutrition is impaired rapidly. These cells cluster to form lumps, swellings, and sometimes produce ulcers in the respective organs.
However in the case of blood cancer — Leukaemia – the abnormal cells start circulating throughout the blood streams so, no visible lump or swellings are observed. (Cancer is known by its different types like sarcoma, lymphoma, leukaemia, myeloma, carcinoma etc.). The most important characterisitc of cancer is that the cancer cells breakaway from the tissue or organ of origin and starts spreading to other parts of the body through lymphatic channels or cavities or blood vessels. They then deposit themselves in other parts of the body where it grows again. This is known as the metastasis. Because of this unique characterisitc it becomes difficult to cure or to control cancer when it has spread.