[1445] Chromosome 20q Deletion — A Recurrent Cytogenetic Abnormality in Chronic Myelogeneous Leukemia Patients in Remission

J Sun, W Cui, CC Yin, S Chen, LJ Medeiros, G Lu. Univ Texas M.D Anderson Cancer Center, Houston, TX

Background: Interstitial deletion in the long arm of chromosome 20, del(20q), is a recurrent cytogenetic abnormality observed in a number of hematological neoplasms, most commonly in myeloproliferative neoplasms, and less commonly in myelodysplastic syndromes (MDS) and acute myeloid leukemias, including therapy-related cases. In chronic myelogeneous leukemia (CML), del(20q) has been reported in some patients undergoing blastic transformation, and is considered a potential candidate responsible for the evolution of disease. However, the presence of del(20q) has never been described in CML patients who are in cytogenetic remission.
Design: We screened cases of CML after therapy at our hospital between 1997 and 2008, and identified 10 patients with del(20q) as the sole abnormality in cytogenetic remission defined as BCR-ABL1 negative by conventional cytogenetics and fluorescence in situ hybridization (FISH).
Results: The median age of patients was 56 years (range, 33-72 years). There were 6 men and 4 women. All patients were treated with imatinib (Gleevec) or nilotinib with or without interferon, Ara-C, homoharringtonine and/or hematopoietic stem cell transplantation, and achieved morphological and cytogenetic remission. Del(20q) occurred before (20%), at time of (30%) or subsequent to (50%) cytogenetic remission, from up to 25 months prior to cytogenetic remission to 38 months after it. None of the patients showed significant dysplasia in bone marrow when del(20q) was identified, nor have they developed MDS or other hematological malignancies at time of most recent follow up (44.3 to 165.4 months after initial diagnosis of CML). At last follow up, their white blood cell and platelet counts were normal; 5/10 (50%) patients had mild anemia (hemoglobin range, 11.0-14.8 g/dL). All patients have remained in morphological and cytogenetic remission. Most recent RT-PCR tests showed none to extremely low levels of BCR-ABL1 fusion transcripts (median, 0.01 BCR-ABL1/ABL1 percentage).
Conclusions: In this setting, del(20q) does not appear to be a marker for MDS. Although it has been described in CML blast phase and implicated in the pathogenesis by others, the presence of del(20q) in this cohort of patients suggests the deletion alone is not sufficient to induce blast transformation of CML.
Category: Hematopathology

Wednesday, March 24, 2010 1:00 PM

Poster Session VI # 194, Wednesday Afternoon


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