The origins of the definition of complete remission in acute myeloid leukemia

The origins of the definition of complete remission in acute myeloid leukemiaThe achievement of a complete remission (CR) for patients with acute myeloid leukemia (AML) has long represented the critical initial goal of therapy with the hope that it portends the likelihood of ultimate cure.How CR for AML is defined has evolved over the years.An early attempt to define CR was published as a letter to the editor in the journal Blood in 1956. 1 The letter came from the Clinical Studies Panel of the Cancer Chemotherapy National Service Center and was authored by Harry Bisel, MD, the executive secretary of the Panel.Dr. Bisel was an oncologist at my institution, the Mayo Clinic, where he founded the Department of Medical Oncology and served as its chair from 1963-1972.He was also one of the founding members of the American Society of Clinical Oncology.In the letter an excellent response to therapy or CR was defined as less than 5% marrow blasts and attainment, for more than 1 month, of a hemoglobin concentration greater than 12 g/ dL, circulating granulocytes (or absolute neutrophil count) greater than 200/mm 3 (1,500/mm 3 for children) and return of platelet counts to greater than 100,000/mm 3 for adults and children.One wonders whether the granulocyte figure of 200/mm 3 may have been a typographic error and was truly meant to be 2,000/mm 3 .Additionally, "subsidence of all evidence of leukemic infiltration" was required as part of a CR.Fair and poor responses were also described in the letter, representing attempts to define partial and no responses, respectively (Table 1).A definition of relapse was also provided.These criteria were applied in a report by Freireich et al. in 1961 of 178 adult and pediatric patients with acute leukemia admitted to the Chemotherapy Service of the National Cancer Institute between October, 1953 and October, 1958. 2 Of the 178 patients, 63 had AML and 115 had acute lymphoblastic leukemia.Treatment consisted of 6-mercaptopurine, methotrexate and corticosteroids.However, by January of 1960, 171 (96%) of the patients had unfortunately died. TITLECriteria for the evaluation of response to treatment in acute leukemia.