Differences in Postrelapse Mortality May be Driving Racial/Ethnic Disparities Observed in Children With Hodgkin Lymphoma

No difference in event-free survival (EFS) was observed in children and adolescents with newly diagnosed Hodgkin lymphoma (HL) according to race/ethnicity; however, postrelapse mortality was found to be higher in nonwhite groups. The findings from this pooled, secondary analysis of data from phase 3 clinical trials of dose-dense, response-adapted therapy were published in the Journal of Clinical Oncology. 

Although worse outcomes for non-Hispanic black patients and Hispanic patients compared with white patients have been previously reported in population-based studies of children and adolescents with HL, questions remain regarding the factors underlying this disparity (eg, differences related to disease/host biology or access to treatment).

In this study, data were pooled from 3 contemporary, phase 3 Children’s Oncology Group (COG) clinical trials evaluating risk-based, dose-dense chemotherapy, as well as additional chemotherapy or radiation therapy based on treatment response, in 1605 children and adolescents aged younger than 1 year to 21 years with de novo HL.

In this patient cohort, 67% were non-Hispanic white, 13% were non-Hispanic black, and 19% were Hispanic race/ethnicity. The median age at diagnosis for the overall study population was 14.6 years, with a higher proportion of nonwhite patients younger than 15 years at diagnosis (P =.01). The proportions of patients with public/government insurance also differed by race/ethnicity: 16%, 41%, and 44%, respectively. In addition, compared with non-Hispanic white patients, nonwhite patients were more likely to reside in areas related to low-socioeconomic status (P =.01) and to have more advanced disease at the time of diagnosis (P =.01).

At a median follow-up of 6.9 years, 5-year EFS was similar in non-Hispanic white (82%) and nonwhite (84%) patients, and the absence of a significant difference in 5-year EFS based on race/ethnicity was maintained following multivariate analyses that accounted for differences in baseline variables.   

“Results of our analyses suggest that, in patients with access to cooperative group trials, uniform risk-directed therapy with a response-adapted, combined-modality approach eliminates the EFS gap by race/ethnicity in children with HL,” the study authors stated.

Nevertheless, although no significant differences in 5-year overall survival (OS) based on race/ethnicity were observed in unadjusted analyses, the risk of all-cause mortality was 1.88-fold higher for nonwhite compared with non-Hispanic white patients on multivariate analyses for OS that adjusted for differences in baseline characteristics such as age at diagnosis, disease histology and stage, and whether radiation therapy was included as part of upfront therapy. Furthermore, the hazard ratios for postrelapse mortality were 3.45 and 2.72 for non-Hispanic black and Hispanic patients, respectively, compared with non-Hispanic white patients.

The study authors noted that “the success of salvage regimens, however, depends not only on disease biology and treatment tolerability, but also on patients having access to these interventions.”

Although incomplete information regarding salvage treatment is a limitation of this study, the study authors speculated that “differences in salvage therapy or supportive care outside of the cooperative group clinical trials may be driving the disparities observed at the population level.”

Reference

Kahn JM, Kelly KM, Pei Q, et al. Survival by race and ethnicity in pediatric and adolescent patients with Hodgkin lymphoma: a Children’s Oncology Group study [published online September 20, 2019]. J Clin Oncol. doi: 10.1200/JCO.19.00812