Justine M. Kahn1, Kara M. Kelly2, Qinglin Pei3, Debra L. Friedman4, Frank Keller5, Rizvan Bush6, Smita Bhatia7, Tara O. Henderson8, Cindy L. Schwartz9, Sharon M. Castellino5
1Columbia University Medical Center, New York, New York, USA,2Roswell Park Comprehensive Cancer Center, Buffalo, New York, USA,3Children‘s Oncology Group, Statistics & Data Center, University of Florida, Gainesville, Florida, USA,4Vanderbilt University School of Medicine, Nashville, Tennessee, USA,5Emory University, Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Atlanta, Georgia, USA,6Children's Oncology Group, Statistics and Data Center, Monrovia, California, USA,7University of Alabama at Birmingham, Birmingham, Alabama, USA,8University of Chicago Comer Children's Hospital, Chicago, Illinois, USA,9Children's Hospital of WI, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
Introduction: Despite excellent survival in pediatric Hodgkin Lymphoma (HL), disparities by race/ethnicity persist: Population-based studies in the U.S. suggest that black and Hispanic (vs. non-Hispanic white) race/ethnicity are associated with inferior outcomes. Whether disparities are observed after adjusting for clinical features and treatment-related variables is not known. We examined whether race/ethnicity is predictive of event-free survival (EFS), and overall survival (OS) in patients receiving risk-adapted, response-based therapy for newly diagnosed HL on contemporary Children's Oncology Group (COG) trials.
Methods: This was a pooled analysis of patient-level data from three COG Phase 3 trials for intermediate, low, high-risk HL (AHOD0031, AHOD0431, AHOD0831). Five-year EFS and OS by age were estimated by Kaplan Meier method. Cox regression models examined the influence of race on EFS and OS, adjusting for age, sex, insurance, histology, Ann Arbor stage, B symptoms, bulk disease, COG study, and radiation therapy (RT).
Results: Median follow-up was 6.9 years. We included 2071 of 2155 patients (1 – 21 years) enrolled on COG HL trials in the U.S. or Canada between 2002 and 2012. Distribution of race/ethnicity was: 64% white (N = 1334), 11% non-Hispanic black (N = 236), 16% Hispanic (N = 329), 3% Asian/Pacific Islander (N = 66), 5% Other (N = 106). More non-Hispanic white patients had private (vs. government) insurance (p < 0.0001). A higher proportion of white patients had nodular sclerosing histology (p < 0.0001) and a higher proportion of black and Hispanic patients had stage III/IV disease (p = 0.0002). There was no difference in B-symptoms (p = 0.19), bulk (p = 0.88), or RT receipt (p = 0.53) by race/ethnicity. In pooled analysis, EFS was 83%, OS was 97% and were not different by race/ethnicity (EFS: p = 0.98; OS: p = 0.29). Cumulative incidence of relapse was 16.8% and did not differ by race/ethnicity (p = 0.93). In multivariable models, there was no significant effect of race/ethnicity on either EFS (p = 0.95), or OS (p = 0.14).
Conclusion: In children treated with contemporary, response-based therapy on COG trials, race/ethnicity was not associated with survival, suggesting that disparities observed in population-based studies may be reduced in children enrolled on clinical trials. Further analyses will explore early response to therapy by race/ethnicity as well as treatment-related toxicities and the independent contribution of socioeconomic status to HL outcomes.