Risk factors for overweight and obesity after childhood acute lymphoblastic leukemia in North America and Switzerland: A comparison of two cohort studies

BACKGROUND: After childhood acute lymphoblastic leukemia (ALL), sequelae include overweight and obesity, yet with conflicting evidence. We compared the prevalence of overweight and obesity between ≥5‐year ALL survivors from the North American Childhood Cancer Survivor Study (CCSS) and the Swiss Childhood Cancer Survivor Study (SCCSS) and described risk factors. METHODS: We included adult childhood ALL survivors diagnosed between 1976 and 1999. We matched CCSS participants (3:1) to SCCSS participants by sex and attained age. We calculated body mass index (BMI) from self‐reported height and weight for 1287 CCSS and 429 SCCSS participants; we then compared those with siblings (2034) in North America and Switzerland (678) siblings. We assessed risk factors for overweight (BMI 25–29.9 kg/m(2)) and obesity (≥30 kg/m(2)) using multinomial regression. RESULTS: We found overweight and obesity significantly more common among survivors in North America when compared with survivors in Switzerland [overweight: 30%, 95% confidence interval (CI): 27–32 vs. 24%, 21–29; obesity: 29%, 27–32 vs. 7%, 5–10] and siblings (overweight: 30%, 27–32 vs. 25%, 22–29; obesity: 24%, 22–26 vs. 6%, 4–8). Survivors in North America [odds ratio (OR) = 1.24, 1.01–1.53] and Switzerland (1.27, 0.74–2.21) were slightly more often obese than siblings. Among survivors, risk factors for obesity included residency in North America (5.8, 3.7–9.0); male (1.7, 1.3–2.3); attained age (≥45 years: 5.1, 2.4–10.8); Non‐Hispanic Black (3.4, 1.6–7.0); low household income (2.3, 1.4–3.5); young age at diagnosis (1.6, 1.1–2.2). Cranial radiotherapy ≥18 Gray was only a risk factor for overweight (1.4, 1.0–1.8); steroids were not associated with overweight or obesity. Interaction tests found no evidence of difference in risk factors between cohorts. CONCLUSIONS: Although treatment‐related risk for overweight and obesity were similar between regions, higher prevalence among survivors in North America identifies important sociodemographic drivers for informing health policy and targeted intervention trials.