New research suggests that childhood cancer survivors – particularly those treated with cranial radiation or chemotherapy with glucocorticoids – are 14 percent more likely to be obese in adulthood than their healthy peers. The study, conducted at St. Jude Children’s Research Hospital in Memphis, Tenn., was published online May 11 in the journal Cancer.
For the study, researchers looked at 1,996 childhood cancer survivors who had been diagnosed with cancer at least 10 years ago and had been treated at St. Jude’s. The average survivor was 32 years old and almost 25 years beyond a cancer diagnosis.
The findings showed that 36.2 percent of the group had a body mass index (BMI) of 30, which falls into the obese category. The research team found one of the strongest obesity predictors was the survivor’s weight at diagnosis. Children who were overweight when their pediatric cancer was found were almost five times more likely to be obese as adults than other survivors.
The researchers also found that 47 percent of survivors who were treated with cranial radiation – used to prevent or delay the spread of cancer in the brain – were obese, compared to 29.4 percent of survivors who received other treatments. Childhood cancer survivors treated with chest, abdominal or pelvic radiation were half as likely to be obese as those who had cranial radiation.
The risk for obesity was even greater for survivors who had been treated with both cranial radiation and glucocorticoids. Obesity was also more common in among survivors who were 5 years or younger at the time of diagnosis as well as among those who had survived 30 years or longer.
In addition, the study authors found that genetic factors may be at play. “The results must be verified, but the findings suggest that variations in genes responsible for neural growth, repair and connectivity may modify the risk of obesity in childhood cancer survivors treated with cranial irradiation,” first author Carmen Wilson, PhD, a research assistant in St. Jude’s department of epidemiology and cancer control, said in a hospital news release.
Because obesity is associated with an increased risk of premature death, heart disease and other chronic health problems, Wilson and her colleagues see the prevalence of excessive weight gain among childhood cancer survivors as a pressing problem.
“Childhood cancer survivors are known to be prone to developing chronic disease. Obesity just adds to that risk,” said corresponding author Kirsten Ness, PhD, a research associate in St. Jude’s department of epidemiology and cancer control.
Calling for weight-loss interventions and counseling for childhood cancer survivors, the authors wrote, “The high prevalence of obesity among survivors underscores the need for immediate focus on research directed at developing effective interventions for weight measurement to optimize health outcomes among survivors of childhood cancer as they age.”