Abstracts

Rationale: Acute seizures occurring at diagnosis or during treatment of childhood cancer has been described. However, the subsequent development of epilepsy has not been well characterized. We sought to describe the circumstances and course of seizures encountered amongst childhood cancer survivors treated with chemotherapy at a single pediatric medical center to characterize patient risk factors, seizure types, and subsequent treatment response. Methods: We reviewed billing records of patients <18 years of age treated at Cook Children's Medical Center between 2006 and 2011 with diagnosis codes for childhood cancer treated with chemotherapy and seizure, then retrospectively reviewed the medical records of this cohort. We excluded patients with nonepileptic seizures and those with a diagnosis of epilepsy prior to cancer diagnosis. Demographic data, seizure characteristics and treatment, cancer characteristics and treatment, and outcome were abstracted for descriptive analysis. Results: Forty three patients underwent chemotherapy treatment and had seizures. Seizure types were characterized as localization-related in 20 (46.5%) patients, generalized in 17 (39.5%), and a combination thereof in 6 (14.0%). Fifteen (35%) had CNS tumors, 24 (56%) leukemias, and 5 (12%) had other cancers. Twenty five (58%) patients had onset of seizures during chemotherapy treatment and 18 (42%) had onset after treatment (median time to onset = 498 days, range=179-5714). Fourteen (33%) patients had seizures only during chemotherapy treatment, while 29 (67%) patients had seizures beyond chemotherapy treatment and were diagnosed with epilepsy. Six (14%) patients developed treatment resistant epilepsy. Patients that developed epilepsy were diagnosed with cancer at an earlier mean age (4.32 vs 8.57y, F(1,40) =8.295, p=0.006). Patients with CNS tumors were significantly more likely to develop epilepsy compared to those with leukemia or other cancer types (F(2,39)=9.714, p=<0.001). There were no significant differences in chemotherapy used or exposure to CNS radiation therapy between those that developed epilepsy and those that did not. Conclusions: While acute seizures during chemotherapy treatment are more common, late onset seizures and epilepsy develop frequently, with a number developing treatment-resistant epilepsy. When seizures occur in patients treated with chemotherapy for childhood cancer, earlier age at cancer diagnosis and a diagnosis of CNS tumor are predictors of subsequent epilepsy development. Additional studies employing a control group of patients treated with chemotherapy without development of seizures would be useful to discover other potential risk factors.