NCO-10INTELLECTUAL OUTCOME IN MOLECULAR SUBGROUPS OF MEDULLOBLASTOMA

Abstract

BACKGROUND: Medulloblastoma subgroups have distinct demographic, genetic and clinical features, yet their respective intellectual outcomes are unknown. With the advent of subgroup-specific therapy de-escalation strategies, it is critical to characterize intellectual functioning in each subgroup according to treatment intensity. METHODS: One hundred and twenty one patients with medulloblastoma (51 Group 4; 25 Group 3; 28 SHH; 17 WNT), treated between 1991 and 2013 at the Hospital for Sick Children (Toronto, Canada), Children's National Medical Center (Washington, DC) or the Lucile Packard Children's Hospital (Palo Alto, CA), had longitudinal intellectual functioning evaluations. First, we compared IQ measures between subgroups, controlling for relevant clinical and demographic variables. Next, we evaluated the effect of: a) radiation intensity (i.e. reduced-dose radiation with a focal tumor bed boost vs. treatments with higher radiation doses and/or larger boost volumes), and b) mutism, on full scale IQ (FSIQ) in each subgroup. Growth curve analysis was used to determine stability or change in IQ scores over time. RESULTS: Subgroups declined comparably in all IQ measures except processing speed (PS). SHH had lower baseline PS, and declined less, than Groups 3 and 4 (all P 0.05). Although FSIQ decline did not differ according to mutism status for any subgroup (all P > 0.05), Group 3 patients with mutism had lower baseline FSIQ (P = 0.014). CONCLUSION: Therapy de-escalation appears to be a suitable way to achieve optimal intellectual functioning in patients with WNT and Group 4 medulloblastoma.