Hispanic Ethnicity Is Associated with Younger Age at Presentation and Worse Survival in AML

Introduction: Previous studies have suggested differences in presentation, prognostic factors and treatment outcomes between blacks and whites with acute myeloid leukemia (AML). Such differences, however, are not well described in Hispanics, who are otherwise known to have higher rates of B-ALL and APL compared to whites. This study aimed to examine the relationship of the hispanic ethnicity with non-APL AML baseline characteristics and treatment outcomes in comparison to non-Hispanic whites.

Methods: All patients diagnosed with AML between the years 2000-2010 were identified within the Montefiore Medical System in the Bronx, NY. Descriptive statistics were used to compare differences in baseline patient and disease characteristics between white and hispanic subjects. Kaplan Meier survival function was utilized to compare the survival experience of patients, stratified by key prognostic factors. Cox PH multivariable models were constructed to look at ethnic differences in overall survival (OS), adjusted for clinically important and statistically significant prognostic variables.

Results: 248 evaluable subjects with newly diagnosed AML were identified, among which 153 were whites (n=80) and Hispanics (n=73). Hispanics were significantly younger at presentation compared to whites [median age 59 (45-71) vs 70yrs (57-82), p<0.001]. The cytogenetic profile of AML in Hispanics (favorable 8.8%, intermediate 49.1%, high-risk 42.1%) was not significantly different when compared to Caucasians (favorable 3.8%, intermediate 58.5%, high-risk 37.7%, p=0.51) A subset of patients (n=81) had mutational testing done, that revealed a higher frequency of p53 mutations in hispanic (7/33, 21%) compared to white patients (1/25, 4%). Other mutations were not significantly different between the groups. 66% of Hispanics were treated with "7+3" induction chemotherapy, compared to only 50% of whites, due to the higher proportion of elderly AML patients in the latter group (p=0.09). Only 68% of those Hispanic AML patients induced, however, achieved complete remission compared to 76% of whites (p=0.45). The rates of allogeneic transplantation were similar in both ethnic groups (H: 12.7%, W: 11.3%, p=0.27). In multivariable Cox PH analysis, adjusted for age, cytogenetic risk group and initial treatment modality, Hispanics were noted to have significantly lower OS compared to whites (HR 1.72, 95%CI 1.02 - 2.88, p=0.04).

Conclusion: In this multiethnic, multiracial, single-center, inner-city adult AML cohort, we report for the first time that even though AML in Hispanics presents at an earlier age, it is associated with worse OS. The higher frequency of deleterious p53 mutations in hispanic AML patients could explain their poorer outcomes. Ongoing mutational studies are testing larger cohorts of patients and will be reported at ASH.