[1354] Early T-Cell Precursor Leukemia: A High Risk Subtype of T-ALL?

Ashleigh A Allen, Anthony Sireci, Foxwell N Emmons, Adrianna Colovai, Govind Bhagat, Bachier Alobeid. Columbia University Medical Center, New York, NY

Background: Early T-cell precursors (ETPs) are early immigrants form the bone marrow to the thymus with a characteristic immunophenotype. A recent study has identified a very high-risk subtype of T acute lymphoblastic leukemia/lymphoma (T-ALL) with the ETP phenotype (ETP-ALL). We analyzed the frequency of ETP-ALL at our institution and investigated its clinical features and prognosis to determine if there is any difference in clinical outcomes.
Design: We searched our archives to identify cases of ETP-ALL (between Jan. 2000 to Aug. 2011). Cases were divided into ETP-ALL and non-ETP-ALL subgroups based on immunophenotype (CD8-, CD1a-, CD5 dim). Clinical parameters reviewed included sex, age, and white blood cell count (WBC) at diagnosis. Risk stratification was based on established National Cancer Institute criteria. We also reviewed outcomes of induction and clinical status on follow-up.
Results: 48 cases of T-ALL were found with adequate information on chart review, of these, 7 were ETP-ALL (14.6%). Age range for ETP-ALL: 4-49y (n=4<18y), mean 16.2y, M/F 6:1; non ETP-ALL: 8 mo. -81y (n=34 <18y), mean 22.9y (p=0.38), M/F 2.4:1. ETP-ALL WBC range: 2.4-148.8 x 109/L (mean 74.6); for non-ETP-ALL: 1.2-593.4 x 109/L (mean 35.9, p=0.23). 29 non-ETP-ALL were high risk, 26 by age (≥10 or <1) and 3 by WBC >50.000 (70.7%, 63.3% and 7.4%, respectively); 5 ETP-ALL were high risk, all by age (71.4%, p=1). Marrow blasts ranged from 0% to 100% for both groups with a mean of 55.2% for ETP-ALL and 29.7% for non-ETP-ALL (p=0.15). 14.29% of ETP-ALL and 12.20% of non-ETP-ALL (p =1) failed induction therapy. 28.57% of ETP-ALL relapsed compared to 26.83% of non-ETP-ALL (p = 1), and 14.29% of ETP-ALL died (including all causes) compared to 26.83% of non-ETP-ALL (p = 0.662) during follow up (range 2 wks. to 8y). There were no significant differences in molecular or cytogenetic findings between the two groups.
Conclusions: ETP-ALL as a subtype of T-ALL can be seen at all ages. Our analysis does not show statistically significant differences between the ETP and non-ETP groups. This could be due to differences in patient populations and different risk groups by age (previous study included only pediatric cases) and/or WBC or in treatment protocols compared to previous study.
Category: Hematopathology

Monday, March 19, 2012 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 231, Monday Morning


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