Adult patients with acute myeloid leukemia who achieve complete remission after 1 or 2 cycles of induction have a similar prognosis

Background: Patients with newly diagnosed acute myeloid leukemia (AML) often have residual leukemia in the bone marrow 10 to 14 days after the start of induction therapy. Some cooperative groups administer a second cycle of similar induction therapy on Day 14 if there is residual leukemia. It is a common perception that the presence of residual leukemia at that point predicts a worse prognosis irrespective of the therapy received. The objective of this study was to determine whether patients who required a second cycle of induction (given on or about Day 14) to achieve complete remission (CR) had a worse prognosis than patients who achieved CR after only 1 cycle, because a worse prognosis may alter postremission therapy. Methods: Patients who were enrolled on 6 consecutive studies for AML that were conducted by the Eastern Cooperative Oncology Group (ECOG) between 1983 to 1993 received induction therapy. If residual leukemia was present in the bone marrow on the Day 14 after the start of induction, then patients were to receive a second cycle of identical induction therapy. All patients who achieved CR after 1 or 2 cycles received the identical postremission therapy. Results: In each of the 6 ECOG studies, the long-term outcome was similar for patients who required 1 or 2 cycles of induction therapy to achieve CR, and their outcome was independent of other prognostic variables, such as age or karyotype. Conclusions: The presence of residual leukemia in bone marrow 10 to 14 days after induction therapy did not predict a worse prognosis if patients received second, similar cycle of induction therapy and achieved CR.