Changes in Body Composition in Children and Young People Undergoing Treatment for Acute Lymphoblastic Leukemia: A Systematic Review and Meta‐Analysis

Ongoing evidence indicates increased risk of sarcopenic obesity among children and young people (CYP) with acute lymphoblastic leukemia (ALL), often beginning early in treatment, persisting into survivorship. This review evaluates current literature on body composition in CYP with ALL during and after treatment. This study adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelinesand was registered at the International Prospective Register of Systematic Reviews (PROSPERO) (CRD42023480732). Three databases (PubMed, MEDLINE (OVID), and CINAHL) were searched until March 2024. Studies with individuals aged 0-21 years with ALL during or after treatment were included. The Joanna Briggs Institute checklist was used to assess the bias risk. Of the 126 studies, 13 were included (eight cross-sectional and five prospective). Eight studies used dual-energy X-ray absorptiometry, three used bioelectrical impedance analysis, two used air-displacement plethysmography, and one applied the four-compartment model. Fat mass (FM) increased early (T2-T3 ≈ +1standard deviation score [SDS]), and remained elevated at treatment end, and was above reference at follow-up (T5 ≈ +0.7 SDS). Fat-free mass (FFM) declined during therapy (lowest at T4 ≈ -0.7 SDS) with partial recovery by T5 (confidence interval crossing 0). Body mass index was elevated in the ALL groups versus controls. Heterogeneity was substantial, reflecting variation in age, assessment timing, and methodology. Despite methodological limitations, this review demonstrates persistent increases in FM and a reduction in FFM during and after treatment. Large, international studies using standardized body composition methodologies and clinically relevant cut-offs are needed to define long-term risks.