Impact of Age at Diagnosis on Pediatric Leukemia Survival

PURPOSE: Although age at diagnosis is a surrogate prognostic factor, it remains an important predictor of pediatric leukemia survival. However, it is not fully understood which prognostic factors are directly related to its effect on survival. We aimed in this study to assess the effect of age at diagnosis on childhood leukemia survival. METHODS: We utilized data from Surveillance Epidemiology and End Result (SEER) of newly diagnosed leukemia (nZ15,215) from 1973–2006. Data on sex, race, clinical subtypes of leukemia, children aged 0–19 years involving 17 SEER registries were assessed for overall and age at diagnosis related survival. The Kaplan-Meier, log rank test, and Cox proportional hazard methods were used to examine the impact of age on survival. RESULTS:Theoverall 5 year survival ratewas 67.9%.There was a statistically significant difference in survival by age group at diagnosis, sex, race, tumor cell type, p! 0.0001. This variability persisted after adjustment for the relevant covariates. Compared to infants, children 1–4 years were 76% less likely to die from leukemia (Adjusted Hazard Ratio (AHR) Z 0.24, 99% CIZ0.21–0.28, Children 5–9 years (AHRZ0.31, 99% CI Z 0.26–0.36), children 10–14 years (AHRZ 0.54, 99% CIZ0.46–0.62) and children 15–19 years (AHRZ0.82, 99% CIZ0.70–0.95) CONCLUSIONS:Age at diagnosis remains a single potent predictor of survival in pediatric leukemia, and infants as well as children 15–19 years present with the worst survival. Since age at diagnosis per se does not influence survival but is related to biological and/or clinical tumor prognostic factors, this study adjusted for the effect of some of these factors but survival variability by age at diagnosis persisted. Therefore, identification of such factors will ensure a meaningful explanation of the impact of age at tumor diagnosis on survival.