Abstracts

Rationale: Brain tumors are the most common solid neoplasm of childhood, making up about 20% of all pediatric cancers. Currently, there is a knowledge gap regarding the characteristics of those patients with pediatric brain tumors who develop epilepsy. This study compares pediatric brain tumor patients with and without epilepsy, with respect to tumor location, grade, type and age of diagnosis. Methods: We performed a retrospective study on all neuro-oncology patients evaluated at Radys Children’s Hospital treated for seizures from 2010 through 2016. Clinical data collected included the presence or absence of epilepsy, the patients’ sex, age at diagnosis, tumor grade, location (with respect to lobe plus a general “subcortical” category) and tumor histology. Patients were classified according to individual World Health Organization (WHO) histologic diagnosis as low grade (WHO I-II) or high grade (WHO III-IV). Patients without a formal WHO grading were defined by individual histology characteristics determined by pathology. Diagnoses were classified by a pediatric neuro-oncologist into the categories listed along the abscissa of Figure 2. Results: 607 patients (51.1% male) were assessed by the neuro-oncology group between 2010 and 2016; of these, 66 (10.8%) developed epilepsy. Ages between groups were similar, with a median age of 8 years at diagnosis (IQR 3-12) among the nonepileptic patients versus 9 years (IQR 2.75-13) among the patients with epilepsy (p = 0.6). Among the epilepsy group, the diagnosis of low-grade glioma and DNET were enriched relative to the non-epileptic group (Figure 1). Localization information was available for 539 patients without epilepsy and 66 patients with epilepsy. Subcortical localization was much more prominent among patients without epilepsy (Figure 2a); and in fact 429/605 (70.9%) of the total cohort had a subcortical localization, only 12 of whom developed epilepsy. When data are reanalyzed with the subcortical localizations removed (Figure 2b) leaving only cortical tumors, temporal localization was enriched among patients with epilepsy (table 2b). For patients for whom tumor grade information was available, lower-grade tumors were enriched in the epilepsy group, with 49/61 (80.3%) of the children with epilepsy having tumors of WHO I-II versus 292/496 (58.9%) of the children without epilepsy (p = 0.001). Conclusions: These findings underline the role that tumor location, type and grade can play in tumor-related epileptogenesis. With respect to localization, the finding that the large majority of pediatric brain tumors are subcortical is consistent with previous literature, and the cortical bias of epileptogenic tumors (particularly with respect to the temporal lobe) is consistent with current understandings of epileptogenesis. The tendency for low grade tumors (particularly low-grade glioma) to result in seizures is consistent with findings in the adult literature. These data will help to better understand the risks of pediatric neuro-oncology patients for developing epilepsy as a comorbidity of their brain tumor.  Funding: None