CD34 expression fails to predict the outcome in adult acute myeloid leukemia.

BACKGROUND The expression of the CD34 antigen on the blast cells of acute myeloid leukemia (AML) has been regarded as an unfavorable prognostic factor for the achievement of complete remission (CR). However, clinical reports on this issue still remain controversial. We evaluated the relationship between CD34 expression, some clinical characteristics and outcome in 80 consecutive adult AML patients. METHODS Immunophenotyping was performed with a FACSCAN flow cytometer and CD34 was tested by HPCA-1 (My10, Becton-Dickinson). Samples were considered positive when at least 20% of cells were labeled. Promyelocytic leukemias were excluded from the study. Sixty-six patients were designed to receive intensive induction chemotherapy; 14 "low-dose" ARA-c. RESULTS AND CONCLUSIONS Forty percent of AML were CD34 positive. In this group there was a higher incidence of less differentiated FAB subtypes (p = 0.03), but not of pre-existing myelodysplasia. No differences were found in complete remission (CR) rate, remission duration or survival. Excluding induction deaths from the analysis, the CR rate was slightly lower in CD34+ AML (55 vs 65%), without any impact on survival. We could not confirm the prognostic relevance of CD34 in adult AML, but larger studies are needed.