Prevalence of FMS-like tyrosine kinase 3/internal tandem duplication (FLT3/ITD+) in de novo acute myeloid leukemia patients categorized according to cytogenetic risk

CONTEXT AND OBJECTIVE: The mechanism involved in leukemogenesis remains unclear and more information about the disruption of the cell proliferation, cell differentiation and apoptosis of neoplastic cells is required. DESIGN AND SETTING: Cross-sectional prevalence study at the Discipline of Hematology, Hospital Sao Paulo, Universidade Federal the SAo Paulo. METHODS: We investigated FMS-like tyrosine kinase 3/internal tandem duplication (FLT3/ITD+) in 40 adult patients with de novo acute myeloid leukemia (AML), categorized according to cytogenetic results, from September 2001 to May 2005. RESULTS: Thirteen patients (32.5%) were classified as presenting the favorable karyotype, 11 patients (27.5%) as an intermediate group, 7 patients (17%) as an undefined group and 9 patients (22.5%) as the unfavorable group. FLT3/ITD* was found in 10 patients (25%): 3 with FLT3/ITD* and favorable karyotype; 4 with FLT3/ITD* and intermediate karyotype; 2 with FLT3/ITD* and undefined karyotype; and only 1 with FLT3/ITD* and unfavorable karyotype. Among the patients without FLT3/ITD+, 10 presented favorable karyotype, 8 intermediate, 4 undefined and 8 unfavorable karyotype. The cytogenetic results showed no correlations between FLT3/ITD presence and the prognostic groups (P = 0,13). We found that 2 patients were still alive more than 24 months later, FLT3/ITD* did not influence the patients' survival rate. CONCLUSION: We found the same frequency of AML with FLT3/ITD* in both the favorable and intermediate prognosis groups. Only one patient presented AML, FLT3/ITD* and unfavorable karyotype (the hypothetical worst clinical situation). Therefore, the prognostic advantage of favorable cytogenetics among patients with FLT3/ITD+ remains to be elucidated, for it to be better understood.