These cells multiply rapidly and replace the normal cells. Bone marrow failure occurs as malignant cells replace normal bone marrow elements. The person becomes susceptible to bleeding and infection as the blood cells lose their ability to function.
Most cases seem to have no apparent cause.
However, radiation, some toxins such as benzene, and some chemotherapy agents are thought to cause leukemia . Abnormalities in chromosomes may also play a role in the development of acute leukemia. Risk factors include exposure to radiation and chemicals, immunosuppression following organ transplantation, and blood disorders such as polycythemia vera, essential thrombocytopenia, and refractory anemia . The incidence is 1 out of 10,000 people. A physical examination shows enlarged liver and spleen.