Prevalence, risk factors and optimal way to determine overweight, obesity and morbid obesity, in the first Dutch cohort of very long-term survivors of childhood cancer: a DCCSS-LATER study

BACKGROUND
Overweight and obesity are common challenges among childhood cancer survivors. Overweight may be disguised, as survivors can have normal weight but high fat percentage (fat%) on dual-energy X-ray absorptiometry (DXA). We aimed to assess prevalence, identify determinants and biomarkers and assess which method captures overweight best, in a nationwide cohort.

METHODS
Prevalence of overweight and obesity, primarily defined by body mass index, was assessed in the DCCSS-LATER cohort of adult survivors treated 1963-2002, with the LifeLines cohort as reference. Associations between risk factors and outcomes were investigated using logistic regression. Additional overweight metrics included DXA-fat%, waist circumference (WC), waist/hip-ratio (WHR), waist/height-ratio (WHtR), and high-molecular-weight-(HMW)-adiponectin.

RESULTS 
2,338 (mean age 35.5y, follow-up 28.3y) survivors participated. Overweight prevalence was 46.3% in men and 44.3% in women (obesity 11.2% and 15.9%, morbid obesity 2.4% and 5.4%), with highest rates among brain tumor survivors. Compared to controls, overweight rate was higher in women >50y, morbid obesity in men >50y. Overweight at cancer diagnosis (adjusted odds ratio (aOR)=3.83, 95%CI=2.19-6.69), cranial radiotherapy (aOR=3.21, 95%CI=1.99-5.18) and growth hormone deficiency (separate model, aOR=1.61, 95%CI=1.00-2.59) were associated with overweight. Using BMI, WC, WHR and WHtR, overweight prevalence was similar. Low HMW-adiponectin, present in only 4.5% of survivors, was an insensitive overweight marker. DXA-based classification identified overweight in an additional 30%, particularly after abdominal radiotherapy, total body irradiation, anthracyclines and platinum. 

CONCLUSIONS
Overweight occurs in almost half of long-term survivors. We identified factors associated with overweight, as well as subgroups in whom DXA can more reliably assess overweight.