The negative prognostic impact of derivative 9 deletions in patients who received hydroxyurea treatment for chronic myelogenous leukemia in the chronic phase

Chronic myeloid leukemia (CML) is characterized by the formation of the BCR/ABL fusion gene, as a consequence of the Philadelphia (Ph) translocation between chromosomes 9 and 22. This study was to investigate the incidence and prognostic significance of derivative chromosome 9 (der(9)) deletions in CML patients who received hydroxyurea treatment in the chronic phase.Fluorescence in situ hybridization (FISH) analysis was used to assess the der(9) deletion status of 48 CML patients in blast crisis (CMLBC).Among the 48 CML patients, 8 (16.7%) showed der(9) deletions, and the deletions were also existent at diagnosis. The median duration of the chronic phase for patients with der(9) deletions was 18 (range 4-38) months compared to 48 (range 0-204) months for patients without deletions (p0.001). Der(9) deletions were not associated with increased karyotypic instability. There was no difference in the probability of the der(9) deletions between the cases having progressed to myeloid or lymphoid blast crisis.The results indicated that the FISH technique could effectively detect der(9) deletions. CML patients with der(9) deletions show more rapid progression and poorer prognosis, and the deletion status is a powerful prognostic factor.