Outcome of Adolescents and Young Adults with Acute Myeloid Leukemia (AML) As Compared to Pediatric AML Patients: Real World Data from SEER Registry

Background: Limited data exists regarding the characteristics and outcomes of adolescents and young adults (AYAs) with acute myeloid leukemia (AML) which are largely under-represented in both pediatric and adult trials. We sought to compare the characteristics and outcomes of AYAs with AML using a large population based registry in the United States.

Methods: We utilized Surveillance Epidemiology and End Results (SEER)-18 registry to identify all pediatric (0-18 years) and AYA (age 19-30 years) patients diagnosed with AML using appropriate histology codes based on the International Classification of Diseases for Oncology, 3rd version.  Patients with acute promyelocytic leukemia (APL) were excluded from all analysis. Survival statistics were computed for each group using actuarial (Kaplan-Meier method) and compared using Z test for comparison of population proportions. Early mortality, defined as mortality within 1 month of diagnosis, was used as a surrogate for treatment related mortality. Kaplan Meier survival curves were plotted and compared using log-rank test. Multivariate analysis was done using logistic regression and Cox proportional hazard regression model. All p values were two sided and the level of significance was chosen at 0.05.

Results: A total of 6343 eligible patients were identified, which comprised 2836 (44.7%) AYAs. A total of 52% (n=3346) were males, whereas 76%(n=4825) were whites.  Histologically, majority of patients (56%; n=3545) were categorized as AML, not otherwise specified, followed by acute monocytic leukemia (9.9%, n=630). Majority (55%; n-3509) of the patients were diagnosed between 2001-2012. The early mortality rate was lower in the pediatric AML patients (pAML) as compared to AYAs (6.2% vs 9.2%; p<0.01). Similarly the  1 year (70.3% versus 62.1%; p <0.01) and 5 year (48.2% vs 36.4%; p<0.01) was higher in pediatric patients as compared to AYAs. Kaplan Meier plot showed worse overall survival of AYAs compared to pAMLs (Figure 1; p value of log rank <0.01).  Multivariate logistic regression showed higher early mortality among AYAs as compared to pAML patients (OR 1.48; 95% CI 1.23-1.79; p<0.01). Similarly Cox regression showed worse overall survival among AYAs as compared to pAML (HR 1.34; 95% CI 1.26-1.44; p <0.01) 

Conclusions: Our population based analysis shows worse overall survival among AYAs as compared to pAML patients. Future clinical trials specifically focused on this age group are warranted to establish appropriate treatment regimens in this population.

Figure 1: Kaplan Meier Survival curve showing cumulative survival among pediatric patients with AML as compared to AYAs. Log rank test showed statistically significant difference between the two curves (p value <0.01)