Leukemia is cancer of the blood cells that originates in bone marrow where blood cells are manufactured. There are four main types, grouped according to how fast it spreads and the type of blood cells affected. Acute leukemia spreads quickly and symptoms appear early. Chronic leukemia spreads more slowly and may not be diagnosed for years. Lymphocytic (or lymphoblastic) leukemia affects white blood cells called lymphocytes. Myelogenous leukemia affects red blood cells or platelets. Symptoms may include swollen lymph nodes, fever, abnormal bleeding, bone pain, swelling or pain in the left abdomen and unexplained fatigue. Treatments may include chemotherapy, radiation and transplants.