Children receiving maintenance therapy for acute lymphoblastic leukemia (ALL) and living in extreme poverty have a nearly 2-fold greater risk of relapse than those not living in extreme poverty, according to research published in Blood.
Researchers conducted a secondary analysis of COG-AALL03N1 (ClinicalTrials.gov ID: NCT00268528), which examined adherence to oral 6-mercaptopurine during
maintenance therapy for ALL, using data from the US Census Bureau to categorize patients living below year-specific federal poverty thresholds. They categorized patients living in extreme poverty as those with federal poverty thresholds above 120% of their yearly household income and estimated hazard of relapse using multivariable proportional subdistributional hazards regression while adjusting for relevant sociodemographic and clinical characteristics.
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A total of 592 patients (68.4% male) were included in the analysis. The median age of patients was 5 years (range, 1-19 years) at ALL diagnosis and 6 years (range, 2-21 years) at study enrollment. The median follow-up time was 7.9 years (range, 0.1-13 years).
The study found that 12.3% of the patients were living in extreme poverty. At 3 years from study enrollment, the cumulative incidence of relapse among those living in extreme poverty was significantly higher than those not living in extreme poverty (14.3% vs 7.6%; P =.04).
After adjusting for age at study enrollment, National Cancer Institute risk group, blast cytogenetics, and time from maintenance, the hazard of relapse among children living in extreme poverty was 1.95-fold (95% CI, 1.03-3.72; P =.04) higher than those not living in extreme poverty.
Including race/ethnicity or parental education level in the model attenuated the effect of extreme poverty (race/ethnicity hazard ratio [HR], 1.68; 95% CI, 0.86-3.28; P =.1; HR, 1.69; 95% CI, 0.84-3.41; P =.1), likely due to collinearity between these variables in the cohort.
Further analysis of factors that may contribute to relapse risk revealed that a greater proportion of children living in extreme poverty were nonadherent to mercaptopurine than those not living in extreme poverty (57.1% vs 40.9%; P =.04). However, the researchers found that nonadherence resulted in minimal attenuation of the association between poverty and relapse risk.
“These data, along with our results showing greater proportion of patients living in extreme poverty who are unable to maintain critical adherence at a level of 95%, indicate that nonadherence to chemotherapy may partly explain the greater number of early relapses,” the study authors wrote in their report. “Future studies should implement screening measures for poverty and assist families with resources that ameliorate these financial hardships.”
Limitations of the study included initiation of the study prior to the routine use of end-of-induction measurable residual disease assessment for patients with ALL, inability to account for the recently recognized high-risk subgroup of Philadelphia-like ALL, inability to use exact annual income for poverty assessment, and the researchers’ arbitrary selection of 120% to define extreme poverty.
Disclosure: One study author declared affiliations with biotech, pharmaceutical, or device companies. Please see the original reference for a full list of authors’ disclosures.
Reference
Wadhwa A, Chen Y, Hageman L, et al. Poverty and relapse risk in children with acute lymphoblastic leukemia: a Children’s Oncology Group study AALL03N1 report. Blood. 2023;142(3):221-229. doi:10.1182/blood.2023019631
