What is leukemia cancer: Leukemia is a termed as a serious cancer that occurs in the tissue that forms blood cells. Leukemia causes the bone marrow to produce abnormal white blood cells which are known as leukemia cells. These cells don’t die when they should and moreover causes damage to the normal cells by stopping their nature of work. Leukemia cells contain three main characteristics.Leukemia cancer also causes multiple myeloma cancer disease.