Changes in body mass index in long-term childhood cancer survivors

Previous studies have reported changes in the body mass index (BMI) with time in childhood cancer survivors (CCSs) during follow-up. The limitations of these studies include that they described only a subgroup of survivors or used questionnaires with self-reported heights and weights. The goal of this study was to examine BMI in a large cohort of long-term CCSs and relate this to the BMI at diagnosis, age, sex, tumor type, treatment, and endocrine defects.

All patients treated for childhood cancer at the Emma Children's Hospital/Academic Medical Center between 1966 and 1996 who had survived for at least 5 years were eligible for inclusion. For 893 CCSs with a mean follow-up of 14.9 years, the BMI at the late effects outpatient clinic was compared with the BMI for the general Dutch population.

For girls, an increased prevalence of obesity was found. Risk factors for developing a high BMI at follow-up were a younger age and a high BMI at diagnosis and treatment with cranial radiotherapy. A significantly increased prevalence of severe underweight was found in all adult subgroups except for females aged 26 to 45 years. An association was found between a low BMI at diagnosis and a low BMI at follow-up. No treatment-related variables could be related to changes in BMI.

The BMI at diagnosis is one of the most important predictors for the BMI at follow-up, and this suggests an important genetic or environmental cause. Adult CCSs are at high risk for developing severe underweight at follow-up. Future studies should focus on the causes and clinical consequences of underweight.