Long-term intellectual outcome in children with posterior fossa tumors according to radiation doses and volumes.

Abstract

To analyze the relationship between craniospinal irradiation (CSI) and intellectual outcome in children with posterior fossa (PF) tumors. A neuropsychological evaluation was performed retrospectively in 31 children, aged 5-15 years, who had received radiotherapy for PF tumors, and who had been off therapy for at least 1 year. Factors evaluated for impact on intellectual outcome were: socioeconomic status, disease presentation, histology, complications, chemotherapy, age at radiotherapy, interval between radiotherapy and testing, and radiation doses and volumes. Patients were divided into 3 subgroups according to the CSI doses (0 Gy [i.e., PF irradiation only], 25 Gy, and 35 Gy), with 11, 11, and 9 patients, respectively. Long-term cognitive impairment occurred in most of the patients, even after PF irradiation only. Moreover, there was a significant correlation between the full-scale IQ score (FSIQ) and the CSI dose, with mean FSIQ scores at 84.5 (SD = 14.0), 76.9 (SD = 16.6), and 63.7 (SD = 15.4) for 0 Gy, 25 Gy, and 35 Gy of CS1, respectively. A marked drop in verbal comprehension scores was noted in children who had received the higher dose. This preliminary study further supports the rationale for de-escalation of CSI doses and volumes in standard-risk PF tumors.