**2. Motivation and aim of the study**

Correct diagnosis of the diverse subtypes of acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) play a central role for individual clinical risk stratification and therapeutic decisions. Modern therapeutic concepts of AML are based on individual risk stratification at diagnosis and during follow-up. The ultimate test of any disease diagnostic algorithm approach is its usefulness in guiding the selection of effective treatment strategies. (Haferlach et al., 2007, Löwenberg et al, 2008b) As discussed above, cytogenetic as well as various genomic markers (gene mutations, gene overexpression) may provide input for algorithms for remission induction and post-remission treatment decisions. At the same time, it remains appropriate to realize that prognostic factors in fact remain a moving target and they are only relevant to therapies available at a given time. Algorithms that provide a basis for risk-adapted therapeutic choices may include immunological markers, cytogenetic factors, molecular markers as well as clinical parameters (e.g., age, attainment of an early or late complete remission) and hematological determinants (e.g., secondary AML, white blood cell count at diagnosis).

On the other hand, the more carefully AML is studied, the clearer it becomes that there is considerable heterogeneity between cases with respect to morphology, immunological phenotype, associated cytogenetic and molecular abnormalities and, more recently, patterns of gene expression. This is reflected in the substantially different responses to treatment. Some entities are becoming so distinct that they are regarded as different diseases with specific approaches to treatment.

In order to improve and simplify the diagnosis and management of AML patients that are diagnosed and treated at the at the University Clinic of Hematology-Skopje we conducted a prospective study to establish and standardize a diagnostic algorithm based on minimal screening tests which will facilitate risk adapted therapy for each single AML patient. The aims of our study were: first, to establish the correct lineage assignment of the blast cells, second, to evaluate the incidence of the favorable genetic markers PML/RAR, AML1/ETO and CBF/MYH11 among the AML cases, then to correlate the obtained results with the patient age, comorbidities, and performance status and consecutively to select the effective treatment strategy for each single acute leukemia patient.
