Comparison of outcome in acute myelogenous leukemia patients with translocation (8;21) found by standard cytogenetic analysis and patients with AML1/ETO fusion transcript found only by PCR testing

Patients with normal-karyotype acute myelogenous leukemia (NKAML) may have undetected genetic abnormalities that could affect prognosis. Screening for known AML-specific genetic abnormalities using the reverse transcription p olymerase chain reaction (RT-PCR) may help in arriving at a more definitive prognosis. To test this hypothesis, 104 patients without translocation (8; 21) and inversion(16), as shown by standard cytogenetic (SC) analysis, were screened for these two genetic abnormalities using RT-PCR. Western blot an alysis for the AML1/ETO fusion protein and fluorescent in situ hybridizatio n (FISH) analysis for t(8;21) were performed in patients for whom we had sa mples. The characteristics and outcome after high-dose cytarabine containin g treatments in five patients with t(8;21) shown by RT-PCR alone were then compared to 21 patients with t(8;21) detected using SC analysis. Eight of t he 104 patients had masked t(8;21) and none had masked inv(16), as shown by RT-PCR. Five of 54 patients with NKAML had a detectable AML1/ETO fusion RN A transcript. Western blot analysis showed the AML1/ETO fusion protein in f our of the seven patients for whom we had samples among the eight with mask ed t(8;21) shown by RT-PCR, All patients with t(8;21) shown by RT-PCR had n egative FISH results. Ninety percent (n=19) of the patients with t(8;21) sh own by SC analysis and 40% (n = 2) of the patients with t(8;21) shown by RT -PCR alone achieved a complete remission (P value 0.03). These data suggest that the outcome of NKAML patients with t(8;21) shown by RT-PCR is not equ ivalent to patients with t(8;21) by SC studies.