Racial and Ethnic Disparities Persist in B-Cell ALL Survival in Children, Young Adults

Racial and ethnic disparities in survival outcomes persist among children and young adults with acute lymphocytic leukemia (ALL), despite overall improvements in survival outcomes in recent decades, according to a study published in The Lancet Haematology.

ALL is the most common pediatric cancer, and previous analyses have found that Black and Hispanic children with ALL who were treated 20-40 years ago had worse overall survival (OS) than other racial and ethnic groups at the time, the study authors noted. Children with low socioeconomic status backgrounds also had inferior OS compared with other children with ALL.

The new study encompassed 21,152 children, adolescents, and young adults with newly diagnosed ALL who were enrolled in 8 completed Children’s Oncology Group clinical trials for ALL in the United States, Canada, Australia, and New Zealand between January 2004 and December 2019. Patients were aged 30 or younger and had race and ethnicity data available.

The main outcomes of interest were event-free survival (EFS) and OS across the following race and ethnicity groups: non-Hispanic White, Hispanic, non-Hispanic Black, non-Hispanic Asian, and non-Hispanic other. Multivariate regression models also examined potential contributors to disparities, including clinical and biological disease prognostic factors and insurance status.

The largest racial or ethnic group was the Non-Hispanic White cohort (n = 13,872), followed by Hispanic patients (n = 4354), non-Hispanic Black patients (n = 1517), non-Hispanic Asian patients (n = 1071), and the non-Hispanic other group (n = 338). While the entire cohort of trial participants included 24,979 patients, only the 21,152 included the analysis had race and ethnicity data available.

In non-Hispanic White patients, 5-year EFS rate was 87.4% (95% CI, 86.7-88.0%). Hispanic patients had a 5-year EFS rate of 82.8% and an HR of 1.37 (95% CI, 1.26-1.49). Non-Hispanic Black patients had a 5-year EFS rate of 81.8%, and an HR of 1.45. Among non-Hispanic Asian patients, 5-year EFS was 88.1%, and non-Hispanic other patients had an EFS of 82.8%.

EFS in Hispanic patients was impacted significantly by prognosticators and insurance status. With those aspects factored in, HR decreased from 1.37 to 1.11. In non-Hispanic Black patients, HR decreased from 1.45 to 1.32 when prognosticators and insurance status were factored in.

There were also differences in OS between the cohorts. Non-Hispanic Asian patients had a 5-year OS of 93.6%, non-Hispanic White patients had an OS of 93.3%, Hispanic patients 89.9%, non-Hispanic Black patients 89.7%, and the non-Hispanic other cohort had an OS of 88.9%. The disparities in OS were more substantial than in EFS—non-Hispanic other patients had an HR of 1.43 for EFS, versus 1.74 for OS, for example.

Notably, the disparities seen in the cohort were only significant in patients with B­-cell ALL, not in patients with T-cell ALL. This was true in both EFS and OS. But overall, the findings suggest there are persistent disparities in ALL outcomes among children, adolescents, and young adults across various racial and ethnic groups. The differences were not entirely explained by disease prognosticators or insurance status.

“One notable mechanism for disparities in health outcomes relates to differences in access to and quality of care across race and ethnicity, which have been shown in general and in subspecialty pediatrics and adult oncology, but are understudied in childhood leukemia,” the authors wrote. “Although treated in clinical trials at centers offering specialized care, there might still have been differences in standardized diagnostic tests, time to treatment initiation, provision of family education, time spent with providers, and supportive care.”

While the large population in the study and the availability of clinical data are strengths, limitations included missing data that led to 15% of the overall cohort being excluded from the analysis. Outcomes were similar in excluded patients, but the authors noted that the distribution of race and ethnicity among included versus excluded patients could be different. Due to barriers to trial enrollment, the study cohort may not be representative of the real-world population, they added.

“Future research elucidating the mechanisms underlying these disparities should include studies of access to and quality of care, particularly during maintenance therapy and among relapsed patients,” the authors concluded. Improving the understanding of race- and ethnicity-based disparities will also require increased clinical trial accessibility, accurate and detailed demographic data collection, and treatment guidelines that serve all populations.

Reference

Gupta S, Dai Y, Winestone LE, et al. Racial and ethnic disparities in childhood and young adult acute lymphocytic leukaemia: secondary analyses of eight Children’s Oncology Group cohort trials. Lancet Haematol. 2023;10(2):E129-141. doi:10.1016/S2352-3026(22)00371-4