Racial disparities persist among young patients with acute lymphoblastic leukemia
Considerable survival gaps exist among young white, Black and Hispanic individuals with acute lymphoblastic leukemia, according to study results presented at ASH Annual Meeting and Exposition.
Researchers also observed poorer outcomes among patients with lower socioeconomic status.
“Substantial disparities in outcomes persist by race/ethnicity and socioeconomic status in the modern era,” Sumit Gupta, MD, staff oncologist at The Hospital for Sick Children in Toronto, said during a press conference. “These disparities are not fully explained by differences in leukemia characteristics. Mechanisms underlying these disparities may vary between specific disadvantaged groups.”
ALL is the most common cancer among children, and outcomes have improved dramatically over the past several decades.
Prior studies have shown disparities in ALL outcomes by race or ethnicity have narrowed but that persistent disparities likely are caused by factors other than socioeconomic status or differences in leukemia biology.
Gupta and colleagues aimed to assess whether disparities by race/ethnicity and socioeconomic status existed in a contemporaneous cohort of children with ALL. They also evaluated whether differences in disease characteristics could explain identified disparities.
Researchers assembled a cohort of 24,979 children, adolescents or young adults (age range, 0 to 30.99 years) with newly diagnosed ALL enrolled in Children’s Oncology Group (COG) frontline ALL trials between 2004 and 2019.
Investigators categorized race/ethnicity as non-Hispanic white (65.6%), Hispanic (20.6%), non-Hispanic Black (7.2%), non-Hispanic Asian (5.1%) or non-Hispanic other (1.6%). They used insurance status as a proxy to determine socioeconomic status. Insurance types included U.S. Medicaid (27.8%); U.S. other (59.6%), which primarily included patients with private insurance; and non-U.S. (12.6%), which primarily included patients from regions with universal health insurance.
Researchers assessed EFS and OS to identify persistent inequities by race/ethnicity and socioeconomic status. They also examined the effect of disease prognosticators, such as sex, age, lineage, white blood cell count, cytogenetics, central nervous system status and minimal residual disease status at the end of induction.
Results showed higher 5-year EFS among non-Hispanic white patients (87.4%) than Hispanic patients (82.8%; HR = 1.37; 95% CI, 1.26-1.49) and non-Hispanic Black patients (81.9%; HR = 1.45; 95% CI, 1.28-1.56; P for comparison < .0001). Non-Hispanic Asian patients achieved outcomes similar to those of non-Hispanic white patients.
Results also showed significantly improved 5-year OS among non-Hispanic white patients (93.3%) than Hispanic patients (90%) and non-Hispanic black patients (89.8%; P for comparison < .0001).
Analysis by insurance status showed non-U.S. patients achieved the highest 5-year EFS rate (89%), followed by U.S. patients with other insurance (86.3%) and U.S. patients with Medicaid (83.2%; P < .0001). The 5-year OS rates also was highest for non-U.S. patients (95%), followed by U.S. patients with other insurance (92.5%) and U.S. patients with Medicaid (90.3%; P < .0001).
Researchers reported considerable variability in traditional disease prognosticators, with the rate of patients with T-lineage ALL among non-Hispanic Black patients (17.6%) being nearly twice as high as the rate among non-Hispanic white patients (9.4%) and nearly three times higher than among Hispanic patients (6.6%; P < .0001).
The addition of disease prognosticators to the analysis substantially attenuated the poorer EFS observed among Hispanic patients, reducing the HR from 1.37 (95% CI, 1.26-1.49) to 1.17 (95% CI, 1.06-1.29), according to investigators. The addition of disease prognosticators and socioeconomic status further attenuated the EFS disparity, reducing the HR to 1.11 (HR = 1-1.22).
By comparison, among non-Hispanic Black patients, the addition of disease prognosticators and socioeconomic status minimally attenuated the difference in EFS outcomes, reducing the HR from 1.45 (95% CI, 1.28-1.65) to 1.32 (95% CI, 1.14-1.52).
The addition of race/ethnicity and disease prognosticators considerably attenuated the superior EFS observed among non-U.S. insured patients, with the HR increasing from 0.79 (95% CI, 0.71-0.88) to 0.94 (95% CI, 0.82-1.09). However, the addition of race/ethnicity and disease prognosticators minimally attenuated the increased risk among U.S. patients on Medicaid, only reducing the HR from 1.21 (95% CI, 1.12-1.3) to 1.16 (95% CI, 1.06-1.27).
“It is possible that we didn’t fully account for things like disease prognosticators. Residual confounding may exist,” Gupta said. “But that seems unlikely to fully explain the magnitude of disparities that we’re still seeing.
“That leaves more uncomfortable mechanisms to consider — things like differential access to care, differential quality of care and ... the possibility that even our pediatric oncology health care systems are delivering systematically different care to patients across racial, ethnic or socioeconomic groups.”
Additional research is necessary to determine the specific causes, Gupta said.
“It is crucial that the mechanisms underlying these disparities be elucidated and that interventions be designed and evaluated,” he said. “The COG ALL Committee is establishing a task force that aims to accomplish [this]. Appropriate expertise and representation in all of these discussions will be key.”
Perspective
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One of the true triumphs in hematologic malignancies is the treatment of children with ALL, the overwhelming majority of whom are now cured of their disease. Although dramatic improvements in outcomes among children with ALL have occurred, health disparities are well-recognized among racial, ethnic and socioeconomically disadvantaged populations.
Using a large group of children, adolescents and young adults treated on COG studies, this study showed white patients were enrolled much more often than Hispanic and Black patients. Further, outcomes were better among white patients. Patients with Medicaid had an inferior outcome compared with other patients with private insurance.
We need further studies to determine why such disparities continue to exist, and whether such disparities may be mitigated by more targeted therapies.
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Gupta S, et al. Abstract 211. Presented at: ASH Annual Meeting and Exposition; Dec. 11-14, 2021; Atlanta.