Intellectual outcome after reduced-dose radiation therapy plus adjuvant chemotherapy for medulloblastoma : A children's cancer group study

Purpose: To investigate the intellectual outcomes of children with medullob lastomas/primitive neuroectodermal tumors (MB/PNET) treated with reduced-do se craniospinal radiotherapy (RT) plus adjuvant chemotherapy. Patients and Methods: Forty-three children with average-risk posterior foss a MB/PNETs underwent longitudinal intelligence testing. All had been treate d with a reduced-dose craniospinal RT regimen (23.4 Gy to the neuraxis, 32. 4-Gy boost to the posterior fossa) and adjuvant chemotherapy. Results: The estimated rate of change from baseline was significant for Ful l Scale Intelligence Quotient (FSIQ), Verbal IQ (VIQ), and Nonverbal IQ (NV IQ) (P < .001 for all three outcomes). The rate of change was estimated to be -4.3 FSIQ points per year, -4.2 VIQ points per year, and -4.0 NVIQ point s per year. Females were more subject to VIQ decline than were males (P = . 008), and young children (< 7 years of age) were more negatively affected t han were older children, with a significant decline in NVIQ (P = .016). Fin ally, patients with higher baseline evaluations suffered greater declines i n IQ than did those with lower baseline scores. Conclusion: This study represents the largest series of patients with avera ge-risk MB/PNETs treated with a combination of reduced-dose RT and adjuvant chemotherapy whose intellectual development has been followed prospectivel y. Intellectual loss was substantial but suggestive of some degree of intel lectual preservation compared with effects associated with conventional RT doses. However, this conclusion remains provisional, pending further resear ch.