[1322] AML and MDS Following Radiation Therapy Are Similar to De Novo Disease and Differ from Other Therapy-Related Myeloid Neoplasms.

Valentina Nardi, Michael Kluk, Eyal Attar, Karen Winkfield, Robert P Hasserjian. Massachusetts General Hospital, Boston; Brigham & Women's Hospital, Boston, MA

Background: Therapy related myeloid neoplasms (t-MN) represent a clinical syndrome including myelodysplastic syndromes (t-MDS) and acute myeloid leukemia (t-AML) occurring after cytotoxic chemotherapy or ionizing radiation therapy (XRT) for a prior, usually neoplastic disorder. The prognosis of t-MN is thought to be much worse than de novo MDS or AML and these patients are thus often treated differently from patients with de novo diseases. However, current XRT protocols expose smaller marrow volumes then earlier protocols and the characteristics of post-XRT t-MN in the current era are unknown.
Design: We searched for patients who developed t-MN over a 5-year period (2004-2009) following a history of XRT, cytotoxic chemotherapy (C) or combined-modality therapy (CMT). As controls, we evaluated consecutive patients during the same time period who were diagnosed with AML or MDS following malignancies treated with surgery alone. We determined the percentage of marrow radiation exposure for patients who had undergone XRT alone. Clinical and cytogenetic features were evaluated and all cases were classified according to the 2008 WHO Classification. Treatment and patient outcome were recorded.
Results: The estimated exposed marrow in the XRT group was 1-20% of the total marrow volume (median 4%). Patents treated with XRT alone had superior survival (p=0.006) and lower incidence of high-risk karyotype (p<0.001) compared to patients treated with C/CMT (Table); survival and cytogenetics were similar in patients treated with C versus CMT. There were no significant differences in the distribution of WHO MDS types, MDS versus AML presentation, or high-risk karyotype between the XRT group and the control post-malignancy AML/MDS patients who did not receive XRT or C/CMT; although median survival was shorter in the latter, this was not statistically significant. AML/MDS treatments did not differ significantly between any of the groups.

Characteristics of Patient Groups
 XRT (n=20)C/CMT (n=72)Post-malignancy (n=21)
Median age (y)736671
AML presentation10/2029/728/21
High-risk karyotype5/1944/68∗9/20
Median survival (m)347∗12
∗Statistically different from XRT group

Conclusions: Post-XRT AML and MDS differ from t-MN occurring post-C/CMT and share genetic features and survival with de novo myeloid neoplasms. These findings suggest that myeloid neoplasms occurring after current XRT protocols are biologically different from those occurring after chemotherapy and should not be classified among the t-MN.
Category: Hematopathology

Monday, February 28, 2011 1:30 PM

Platform Session: Section B, Monday Afternoon


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