BACKGROUND: Cytosine arabinoside-based chemotherapy coupled with anthracycline 
is currently the first-line treatment for acute myeloid leukaemia (AML), but 
diverse responses to the regimen constitute obstacles to successful treatment. 
Therefore, outcome prediction to chemotherapy at diagnosis is believed to be a 
critical consideration.
METHODS: The mRNA expression of 12 genes closely involved in the actions of 
cytosine arabinoside and anthracycline was evaluated by real-time reverse 
transcriptase PCR (RT-PCR), in 54 diagnostic bone marrow specimens of M2-subtype 
AML.
RESULTS: Low expression levels of ribonucleotide reductase M2 (RRM2) and high 
expression levels of topoisomerase 2 beta (TOP2B) were correlated with longer 
survival in a univariate analysis. Another interesting finding is that high 
ratios of TOP2B/RRM2 and TOP2B/TOP2 alpha (TOP2A) in a combined analysis were 
also shown to have a prognostic impact for longer survival with improved 
accuracy. Among the four markers, when adjusted for the influence of other 
clinical factors in multivariate analysis, the TOP2B/TOP2A ratio was 
significantly correlated with treatment outcomes; patients with high ratios 
trended toward longer disease-free survival (HR, 0.24; P=0.002) and overall 
survival (HR, 0.29; P=0.005).
CONCLUSION: Genes with distinct expression profiles such as TOP2B/TOP2A 
expression ratio at diagnosis can be employed for outcome prediction after the 
treatment with standard regimens in AML patients with M2 subtype.