Age and genetics: how do prognostic factors at diagnosis explain disparities in acute myeloid leukemia?

Abstract

Objectives: Survival disparities in acute myeloid leukemia (AML) among blacks and Hispanics have been described but not studied extensively in adults. Although younger age and cytogenetic profiles of t(8;21) and acute promyelocytic leukemia (APL) subtypes of AML are associated with improved survival, these factors have not been investigated by race. The purpose is to evaluate whether the observed survival differences for blacks and Hispanics with AML are attributable to older age at diagnosis or lower rates of favorable cytogenetic profiles at diagnosis. The hypothesis is that survival disparities for blacks and Hispanics with AML will be explained by older age at diagnosis and lower rates of favorable cytogenetics.

Methods: Patients with AML were identified in the Surveillance Epidemiology and End Results database (1999 to 2008). Kaplan-Meier (KM) survival curves predicted survival by race/ethnicity, stratified by age. Cox proportional hazard models estimated mortality by race with adjustment for age, sex, year of diagnosis, t(8;21), and APL subtypes.

Results: A total of 25,692 patients were included. Blacks and Hispanics were diagnosed at younger ages (younger than 61 y), and had higher rates of t(8;21) and APL compared with non-Hispanic whites (NHWs). The overall KM curve shows that NHWs had a worse survival compared with other races/ethnicities. However, when KM curves were stratified by age, blacks and Hispanics had worse survival in younger age categories (younger than 61 y). In multivariable models, black race was associated with an increased risk of death compared with NHWs (HR, 1.10; 95% CI, 1.04-1.16). Adjustment for t(8;21) and APL subtypes did not attenuate the disparity.

Conclusions: Despite younger age and higher prevalence of favorable cytogenetics at diagnosis, blacks and Hispanics have an increased mortality from AML compared with other racial/ethnic groups. Future studies should investigate other factors that may influence outcomes among minority populations.