Radiation reduces long-term survival of low-grade pediatric gliomas
The first comprehensive, large-scale cohort study of the long-term survival of children treated for low-grade gliomas, the most common pediatric brain tumor, finds that almost 90% are alive 20 years later and that few die from the tumor as adults. However, children who received radiation as part of their treatment had significantly lower long-term survival rates than children who were not radiated. These findings stand regardless of whether surgeons could successfully remove a child's entire tumor or only part of it, suggesting that the radiation itself may explain the difference.
Delivery of radiation to children's developing brains has been linked to a number of adverse long-term effects, including cognitive development and endocrine function. Although a number of major hospitals have almost eliminated radiation in treating low-grade gliomas, the extent to which other institutions employ radiation varies, according to the study's senior author, Peter Manley, MD, of the Brain Tumor Center at Dana-Farber Cancer Institute and Boston Children's Hospital, in Boston, Massachusetts. The findings were reported in Pediatric Blood and Cancer (2014; doi:10.1002/pbc.24958).
“We found for the first time that, once you survive your childhood with a low-grade glioma, you are not likely to die of that tumor as an adult,” Manley said. "This is incredibly encouraging for patients and families. However, we also found some things that we are currently doing to treat low-grade gliomas, such as radiation, are increasing the rate of death later, so that as an adult you won't die of the tumor, but you may die from the treatment.”
“We strongly recommend treatments that are less likely to cause long-term effects and second cancers," Manley said. “According to our analysis, radiation was the most common factor linked to differences in mortality among long-term survivors," he added. “There are multiple options available today for treating children with these tumors. We should exhaust all those before considering the use of radiation."
To better understand survival factors among this population, Manley, along with lead author Pratiti Bandopadhayay, MBBS, PhD, also of Dana-Farber/Boston Children's Hospital, and their collaborators analyzed Surveillance, Epidemiology and End Results (SEER) data from the National Cancer Institute on more than 4,000 patients diagnosed with pediatric low-grade gliomas between 1973 and 2008. Radiation was part of the treatment for 18% of the patients in the cohort.
Overall, the prognosis for children with low-grade gliomas is quite good, with 5- and 10-year survival rates approaching 90%. Manley and his colleagues found little drop-off in survival at 20 years posttreatment, with almost 90% of pediatric survivors still alive. Strikingly though, only about 70% of patients treated with radiation were still alive 20 years after treatment.
"There is an impression that children diagnosed with anything more aggressive than a grade 1 tumor do poorly in the long term," said Manley. "However, we found, regardless of whether the diagnosis is grade 1 or grade 2, children with low-grade gliomas still do well."