Natural history of central nervous system acute leukemia in adults

Central nervous system (CNS) involvement occurred in 45 of 222 (20.3%) leukemic adults achieving bone marrow (BM) complete remission (CR), including 12 of 23 (52%) acute undifferentiated leukemia (AUL), 12 of 32 (39%) lymphoma leukemia, 5 of 26 (19%) acute lymphoblastic leukemia, and 16 of 142 (11%) acute myelogenous leukemia. Risk factors for CNS disease were lactic dehydrogenase (LDH) ≧600 mU/ml, AUL morphology, and extramedullary involvement, reflecting the importance of disease bulk and biologic idiosyncrasies. For primary CNS relapse, leukocyte count ≧25,000/mm³. AUL morphology, age < 20 years, and extramedullary involvement were most significant. Pattern of CNS involvement varied with morphology. Survival after CNS relapse depended most on BM status and symptoms. Duration of CNS CR was longest for asymptomatic patients with low CSF cell counts. Also important were duration of first BM CR, ease of achievement of initial BM CR, and leukocyte count (original and at most closely antecedent BM involvement), reflecting the common origin of BM and CNS leukemic cells. Central nervous system relapse generally did not shorten BM CR or survival, although early primary CNS relapse was associated with early BM relapse.