Acute Megakaryocytic Leukemia (AMegL) Is Associated with Inferior Outcomes Relative to Other Acute Myeloid Leukemia (AML) Morphologies

Abstract

Introduction: Acute Megakaryocytic Leukemia (AMegL) is a rare subtype of Acute Myeloid Leukemia (AML) resulting from uncontrolled proliferation of megakaryoblasts. Due to its rarity it is unclear if AMegL morphology is independently associated with outcomes in AML.Methods: We used the Surveillance, Epidemiology and End Results (SEER) 18 database to identify adult patients with AML diagnosed between 1991-2011 using the appropriate International Classification of Disease (ICD-O-3) histology codes. Cases of APL (M3) were excluded. Kaplan Meier Survival curves were generated to compare survival statistics between AMegL subtype and the rest of AML types. Multivariate analysis was done using Cox Linear Proportional Hazard Regression model. Statistical analysis was done using Statistical Package of Social Sciences (SPSS) version 21.0 (IBM Corporation, Armonk, NY).Results: Of 45,564 cases of AML identified, 304 (0.7%) belonged to the AMegL subtype. The median ages were 69 (range 18-111), and 67.5 (range 18-92) years, respectively (p value 0.08); the proportion of males were 54.3% and 59.2% respectively (p value 0.09), the median year of diagnosis was 2004 in AMegL versus 2002 in other AML. Whites comprised 82.6% and 84.7% respectively. The 5 year overall survival rates were 17.5% and 10.6% respectively. Kaplan Meier Survival curves showed significantly inferior survival for AMegL relative to other AML cases (p value of log rank test 0.01). On multivariate analysis AMegL was as an independent predictor of increased mortality (adjusted RR 1.23, 95% CI 1.09-1.38, p value <0.01), after adjusting for age of diagnosis, sex, race and year of diagnosis. This remained significant after removing core binding factor leukemia cases from the analysis (RR 1.21; 95% CI 1.07-1.36, p value <0.01)Conclusion: AMegL is a rare subtype of AML which is associated with significantly worse survival in comparison to other AML subtypes. We recommend that the National Comprehensive Cancer Network (NCCN) consider adding AMegL morphology to the list of adverse prognostic factors and as a reason to consider allogeneic stem cell transplantation.Table 1:Multivariate Analysis showing the independent predictors of survival in the study population.VariableRR95% CI of RRP value LowerUpperAML M7 type1.2291.0921.3830.001Race - White - American Indian/Alaska Native - Asian or Pacific Islander - Black1.0 1.166 0.957 1.1120.994 0.919 1.0701.366 0.996 1.1560.06 0.03 <0.01Age at diagnosis1.0351.0341.036<0.01Year of Diagnosis0.9850.9830.987<0.01Male Sex1.0401.0191.061<0.01 DisclosuresNo relevant conflicts of interest to declare.