Survival of cancer in childhood is increasingly common with modern therapeutic protocols but leads frequently to adverse long-term impacts on health, including metabolic and cardiovascular disease. Changes in body composition, especially an increase in fat mass and a decrease in muscle mass, are found early in patients with pediatric cancer, persist long after treatment has been completed and seem to contribute to the development of chronic disease. This review details the effects of such changes in body composition and reviews the underlying pathophysiology of the development of sarcopenic obesity and its adverse metabolic impact. The authors discuss the particular challenges in identifying obesity accurately in survivors of pediatric cancer using available measurement techniques, given that common measures, such as body mass index, do not distinguish between muscle and adipose tissue or assess their distribution. The authors highlight the importance of a harmonized approach to the assessment of body composition in pediatric cancer survivors and early identification of risk using “gold-standard” measurements. This will improve our understanding of the significance of adiposity and sarcopenia in this population, help identify thresholds predictive of metabolic risk, and ultimately prevent or ameliorate the long-term metabolic and cardiovascular impacts on health experienced by survivors of cancer in childhood.

Survivors of pediatric acute lymphoblastic leukemia (ALL) often have altered body composition secondary to treatment effects, including sarcopenic obesity (SO), which increases the risk of both metabolic complications and frailty. SO is difficult to detect without using advanced imaging techniques to which access is often limited. To explore whether common clinical indices can reliably identify the presence of SO in a cohort of long-term survivors of ALL, the discriminatory capacity of body mass index (BMI) or triponderal mass index (TMI, kg/m 3 ) for detecting SO was assessed. Thresholds of BMI and TMI associated with overweight or obesity status had poor sensitivity (< 50%) and specificity for detecting SO. Total misclassification rates at these thresholds exceeded 50% and positive likelihood ratios were nonsignificant. Notably, TMI is more strongly correlated with elevated adiposity than is BMI in this survivor population (R 2 = 0.73 vs. 0.57), suggesting further exploration is warranted. Our study is limited by the sample size, precluding detailed regression analysis. This study highlights the challenges of identifying SO in survivors of pediatric ALL using common clinical indices. Prospective evaluation of additional potential surrogate markers in survivors, in conjunction with the component features of SO, should be a key focus of future research.