MPO and acute myeloid leukemia: Between Group A and B, there was no significant difference regarding age, sex predominance, French-American-British (FAB) subtype, white blood cell (WBC) count, cytogenetic risk, performance status before treatment, or the proportion of patients in which less than 50% of AML cells were positive for myeloperoxidase (MPO), although the number of patients who required 2 or more remission induction therapies to achieve hematologic CR was 14 in Group A and 2 in Group B (P=.0067).