High incidence of CD56 expression and relapse rate in acute myeloid leukemia patients with t(8;21) in Taiwan.

BACKGROUND AND PURPOSE CD56 is a marker of natural killer cells, but can also be found on blast cells in acute myeloid leukemia (AML). The prognostic implications of CD56 expression in AML are not clear. In this study, we evaluated the correlation among CD56 expression, cytogenetic abnormality, and clinical outcome in AML. METHODS CD56 expression was analyzed in leukemic cells from 94 adults with primary AML in Taiwan and was correlated with clinical and hematologic features, cytogenetics, and immunophenotypes of the leukemia. RESULTS Thirty patients (32%) showed CD56 expression. CD56+ AML patients had a higher lactate dehydrogenase level than CD56- patients (1.136 vs 730 V/L, p = 0.048). Patients with t(8;21) had a significantly higher incidence (89%, 8/9) of CD56 positivity in leukemic cells than those with normal karyotype or other cytogenetic abnormalities (26%, 22/85, p < 0.001). In general, there was no difference in overall survival time in CD56+ and CD56- AML patients. However, three patients had central nervous system involvement at initial presentation; two of these had concomitant CD56 expression and t(8;21). In addition, five of the seven patients with t(8;21) and CD56 expression who achieved complete remission later relapsed. CONCLUSIONS The incidence of CD56 expression in AML patients with t(8;21) is very high in Taiwan, and it may imply a poor prognosis in this subgroup of patients.