The Persistence of Extramedullary Leukemic Infiltrates during Bone Marrow Remission of Acute Leukemia.

By BOYD A. NIES, GERALD P. BODEY, Louis B. THOMAS, GEORGE BRECHER AND E fIL J. FREIREICH F OLLOWING the successful treatment of a patient with acute leukemia, evidence of residual leukemia by bone marrow, peripheral blood, or physical examination is often absent. Invariably, however, infiltration of the bone marrow by leukemic cells recurs. Whether a few undetectable leukemic cells remain during remission or whether leukemic cells are reinduced by a persisting etiobogic agent is not known. Skipper has shown in the L1210 mouse leukemia model system both that a single leukemic cell will eventually cause death, and also that “cure” can be accomplished only in those animals in which there is a statistical possibility of having eliminated all leukemic cells.1 These observations suggest that, in mice, recurrences are due to survival of a few leukemic cells. In order to explore this problem in man, patients with acute leukemia dying during bone marrow remission were studied to determine if leukemic cell infiltrates were present in their organs and tissues.