Abstract 1781: Ethnic disparity in pediatric leukemia relapse

Abstract Background: Leukemia is the most prevalent pediatric malignancy, representing 25% of all cancer diagnoses among children. Despite recent substantial improvements in therapy that have dramatically increased survival, 10-20% of cases develop relapse and become refractory to treatment. Although racial/ethnic disparity in survival is well documented, limited knowledge currently exists on the disparity in relapse. The objective of this study was to compare the risk of pediatric leukemia relapse between Hispanic Whites and non-Hispanic Whites. Methods: The study included children (<21 years) diagnosed with leukemia between January 2006 and December 2014 at the All Children's Hospital Johns Hopkins Medicine, St. Petersburg, FL. Patients’ demographic and clinical information were obtained from an electronic health record-derived data warehouse. Ethnicity was self-reported. Leukemia diagnosis and relapse were identified using appropriate ICD-9 codes. Relapse-free survival was defined as the time from diagnosis to the first documentation of relapse. Hazard ratios (HR) and 95% confidence intervals (95% CI) for relapse-free survival were calculated using Cox proportional hazard models adjusting for age at diagnosis, gender and type of insurance (commercial vs government). Results: The study included 66 Hispanic Whites and 202 non-Hispanic Whites. The median age for both groups was 7 years. However compared to non-Hispanic Whites, Hispanic Whites were more likely to be males (59% vs 53%), to have government insurance (71% vs 35%) and had a shorter median follow up time (52 vs 66 months). Approximately 15% of Hispanic Whites developed relapse compared to only 5% non-Hispanic Whites. Kaplan-Meier survival analysis showed a difference in relapse between the two groups (log-rank p = 0.006). After adjusting for age at diagnosis, gender and type of insurance, Hispanic Whites were three times more likely to develop relapse compared to non-Hispanic Whites (HR = 3.1, 95%CI = 1.2-8.0, p = 0.02). Conclusion: Although the findings of this study suggest that ethnic disparity in pediatric leukemia may exist, our findings are limited by the inability to control for potential confounders such as medication adherence, timing of diagnosis, white blood cells at diagnosis and minimal residual disease. Future studies should further investigate this racial/ethnic disparity. Citation Format: Mirinda Gillespie, Greg Hale, Ernest K. Amankwah. Ethnic disparity in pediatric leukemia relapse. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1781.