Emerging evidence suggests that environmental air pollution may adversely influence treatment outcomes in children with acute lymphoblastic leukaemia (ALL). Fine particulate matter (PM₂.₅), a major component of ambient air pollution, has been associated with systemic inflammation, oxidative stress, and immune dysregulation, all of which may affect the response to cancer therapy.¹ A recent study published in JNCI Cancer Spectrum investigated whether PM₂.₅ exposure during induction chemotherapy influences minimal residual disease (MRD), a well-established predictor of relapse and survival in paediatric ALL.²

Hoang and colleagues analysed data from 2,125 children diagnosed with ALL. Daily PM₂.₅ concentrations were estimated using patients' residential addresses and treatment centre locations throughout induction therapy. The investigators then evaluated the relationship between average PM₂.₅ exposure and end-of-induction (EOI) MRD while adjusting for important clinical and demographic variables.²

Among children with B-cell acute lymphoblastic leukaemia (B-ALL), higher residential exposure to PM₂.₅ during induction therapy was associated with significantly greater odds of persistent MRD at the end of induction. Children in the second and third exposure quartiles demonstrated a 51%–56% higher likelihood of MRD positivity compared with those in the lowest exposure group. This association was even more pronounced in patients with National Cancer Institute (NCI) high-risk B-ALL, where adjusted odds ratios ranged from 1.73 to 2.28. Interestingly, the highest PM₂.₅ exposure quartile did not show a statistically significant increase in MRD positivity, suggesting that the relationship may not be strictly linear.²

MRD remains one of the most powerful prognostic markers in paediatric ALL, guiding risk stratification and therapeutic decision-making. Persistent MRD after induction is strongly associated with an increased risk of relapse and inferior long-term survival.³ The present findings therefore raise the possibility that environmental factors such as air pollution may contribute to treatment response in addition to established biological and genetic determinants.

Although causality cannot yet be established, this study highlights the need for further prospective research exploring the biological mechanisms linking PM₂.₅ exposure with leukaemia outcomes. Reducing exposure to ambient air pollution during intensive chemotherapy may represent a simple supportive strategy to optimize treatment response in children with high-risk B-ALL.

References:

1. Hunger SP, Mullighan CG. Acute lymphoblastic leukemia in children. N Engl J Med. 2015;373:1541-1552.

2. Hoang TT, et al. Residential fine particulate matter exposure during induction therapy and end-of-induction minimal residual disease in pediatric acute lymphoblastic leukemia. JNCI Cancer Spectrum. 2026.

3. Brown PA, et al. Children's Oncology Group recommendations for pediatric acute lymphoblastic leukemia risk stratification and management. J Clin Oncol. 2023.