NCO-03: NEUROPSYCHOLOGICAL FUNCTIONING IN THE FIRST YEAR FOLLOWING DIAGNOSIS OF PEDIATRIC MEDULLOBLASTOMA: PRELIMINARY RESULTS FROM CHILDREN'S ONCOLOGY GROUP (COG) ACNS0331

BACKGROUND: Cognitive late effects in survivors of medulloblastoma are well-documented; however, the onset and development of domain-specific difficulties have not yet been well-described in large, prospective samples of children. We aimed to examine neuropsychological functioning of children receiving treatment for medulloblastoma on a COG protocol within the first year after diagnosis. METHODS: Children aged 8 and older who were diagnosed with medulloblastoma and treated on COG ACNS0331 were invited to participate in neuropsychological testing as part of the original study design or, later, in conjunction with COG protocol ALTE07C1. All children received 24 Gy of cranial-spinal radiation with a boost either to the tumor bed or to the entire posterior fossa as well as standard chemotherapy. Participants were evaluated at 9 (+ 3) months post-diagnosis with a battery measuring intellectual functioning, processing speed, and working memory. RESULTS: One hundred sixty-one participants (mean age = 12.3, range = 8-20, 61.5% male, 77.6% white) were evaluated. Early medical complications included 19.3% (n = 31) children with cerebellar mutism and 29.8% (n = 48) with treated hydrocephalus. Mean estimated IQ was in the average range, as measured by age-appropriate versions of the Wechsler scales (Mean = 96.4, SD = 15.4). In contrast, processing speed scores were impaired (Mean = 80.3, SD = 13.6). Estimated IQ and processing speed scores were unrelated to baseline demographics; however, slower processing speed was significantly associated with treated hydrocephalus (Treated hydrocephalus M = 73. 3; F = 3.31, p <.05). CONCLUSIONS: Children with medulloblastoma evidenced impaired processing speed in the first year after diagnosis, which was further diminished for children with treated hydrocephalus. Slower processing speed has been linked to reduced white matter volume in children treated with cranial radiation. These deficits may be the first indicator of emerging, treatment-related cognitive late effects.