Leukemia is a form of cancer affecting the bone marrow and blood cells. It is classified in two major ways: acute leukemia, which sees a rapid spread of the malignancy, and chronic leukemia, in which the malignancy spreads more slowly. While it is one of the forms of cancer associated with children, over 90 percent of all leukemia patients are adults. Symptoms include profuse bleeding from small injuries, easy bruising, night sweats, fatigue, malaise, headaches and unexplained weight loss. Treatment typically centers on chemotherapy and radiation therapy, though bone marrow transplant surgery may also be an option in certain cases.