Burden of sarcopenia and impact of structured physical programme in children with acute lymphoblastic leukaemia

Background: Survival in pediatric acute lymphoblastic leukemia (ALL) now exceeds 80%, yet treatment-related muscle loss may adversely affect functional outcomes. Data on sarcopenia in Asian pediatric ALL populations remain limited. This study aimed to determine the prevalence of low muscle mass in children with ALL at a tertiary pediatric center and to explore the feasibility of longitudinal muscle assessment within a small exercise pilot subgroup.

Methods: This was a cross-sectional prevalence study with an embedded pilot feasibility case series. Children newly diagnosed with ALL in Hong Kong Children’s Hospital between January 2022 and March 2024 were included in the prevalence cohort. Patients newly diagnosed between April and June 2024 were eligible for the pilot feasibility subgroup. Whole-body muscle mass was obtained from Dual-energy X-ray absorptiometry (DXA) scans. Muscle Mass Index (MMI) was calculated as whole-body lean mass divided by height squared (kg/m²). Sarcopenia was operationally defined as MMI z-score <−2 based on age- and sex-specific reference values. In the pilot subgroup, muscle mass, physical performance, bone mineral density (BMD), and trabecular bone score (TBS) were assessed at two fixed time points: within two months of diagnosis (T1) and four to six months post-diagnosis (T2). Participants completed an 8-week structured exercise program between assessments.

Results: Seventy-six children were newly diagnosed during the study period; 24 underwent at least one DXA scan and were included in the prevalence analysis [mean age 10.8 years, interquartile range (IQR) 8 to 14 years; 58.3% male]. The prevalence of sarcopenia was 26%. In the six-patient pilot subgroup, all participants demonstrated low MMI and reduced muscle performance at baseline. The exercise program was completed without dropouts. Improvements in muscle mass and functional measures were observed between T1 and T2; however, the study was not powered to determine intervention efficacy.

Conclusions: Sarcopenia is common among children with ALL in this single-center cohort. Larger prospective studies are needed to determine clinical implications and to evaluate structured exercise interventions in controlled settings.