CSF biomarkers of neurotoxicity in childhood cancer survivors after cranial radiotherapy or surgery

Abstract Objective Treatment of pediatric brain tumors is associated with potential long‐term cognitive sequelae. Patients treated with craniospinal irradiation for posterior fossa tumors are at high risk. New biomarkers that could help to differentiate treatment effects from other causes of cognitive dysfunction would be valuable in tailoring optimal survivorship care. Biomarkers that reflect biological mechanisms behind treatment‐associated cognitive decline would also be important in the evaluation of future treatment regimens for pediatric brain or skull base tumors. Methods In this biomarker‐finding study, 10 adult survivors of pediatric medulloblastoma, skull base tumors, and posterior fossa low‐grade glioma underwent study specific lumbar puncture at a minimum of 17 years following treatment. We analyzed cerebrospinal fluid biomarkers reflecting neuron and astrocyte integrity, amyloid metabolism, inflammation, extracellular matrix, synaptic integrity, and blood–brain barrier function. The values were compared with biomarker levels in healthy controls of comparable age. Results Biomarkers reflecting neuronal injury (neurofilament light chain protein), astrocyte injury or activation (glial fibrillary acidic protein) as well as inflammation (YKL‐40) were significantly elevated in cancer survivors compared to controls. Biomarkers reflecting amyloid metabolism showed a pattern of decrease in patients treated for medulloblastoma. Interpretation The results suggest a potential chronic low‐grade neurodegeneration and astrocyte activation in patients treated for pediatric brain or skull base tumors. Protein biomarkers of CNS disease could potentially be used to increase our understanding of the contribution from different tumor treatments with regard to long‐term symptoms in cancer patients.