Impact of Age at Diagnosis and Hypothalamic Involvement on Body Mass Index Z-Score Change in Pediatric Brain Tumor Survivors.

Background: Obesity risk is increased for pediatric central nervous system tumor survivors. Hypothalamic involvement (HI) by tumor or treatment increases the risk. In healthy children, body mass index (BMI) normally declines until adiposity rebound (AR). We hypothesized that HI and diagnosis before AR would lead to increased BMI at follow-up.

Methods: A chart review of 114 brain tumor survivors diagnosed between 2001-2011 at the Children's Hospital of Wisconsin extracted tumor location, treatment and BMI z-scores at diagnosis and 2-year follow-up. Children were categorized based on age at diagnosis relative to AR and presence/absence of HI.

Results: Children diagnosed pre-AR and post-AR with HI had higher BMI z-scores at 2-year follow-up (pre-AR: 1.6, post-AR: 1.3) than at diagnosis (0.5, 0.6). All groups without HI showed no increase in BMI z-score from diagnosis to 2-year follow-up (pre-AR: 0.7-0.6, during AR: 0.7-0.8, post-AR: 0.7-0.8). The pre-AR and during-AR cohorts with HI had a higher BMI z-score at 2-year follow-up relative to those without HI, while the post-AR group did not.

Conclusion: Except for the post-AR group, patients with HI have increased BMI at 2 years after diagnosis compared to those without HI. Diagnosis pre-AR is associated with greater follow-up BMI z-score.