gerexs writes: "Cancer is a kind of disease characterized by uncontrolled division of cells and the ability of these cells to invade other tissues, either by direct growth into its neighbor tissue or by implantation into distant sites by metastasis. A process called staging helps in assessing the prognosis and in determining the most appropriate treatment to the unrestrained growth of cancer cells. It is used by physicians to describe the extent of spread of a cancer. In this system, cancer is being classified into four stages. Stage I — there's no involvement of lymph nodes and no spread of the cancer from metastases or its original site. Stage IV — the advance cancer, with both distant metastases and lymph node involvement."