Glioma features and seizure control during long-term follow-up

BACKGROUND: An epileptic seizure is a common presenting symptom of glioma, or epilepsy may develop later during the disease. Epileptic seizures affect the quality of life in patients with glioma. Good seizure control during 6–12 months follow-up has been associated with gross total resection, radiation therapy and chemotherapy of gliomas. Little is known about seizure control during long-term follow-up and about factors which may affect the prognosis of epilepsy in glioma patients. METHODS: We identified retrospectively all adult patients with diffuse glioma (grade 2–4) associated epilepsy (n = 123) living in Helsinki, who received treatment at Helsinki University Hospital neuro-oncology center during 2013–2015. We excluded patients with histopathological diagnosis prior to 2005. Data was collected from medical records for five years after diagnosis of glioma, or until death. RESULTS: In this patient cohort 49 (39.8 %) had grade 2 glioma, 19 (15.4 %) had grade 3 glioma and 55 (44.7 %) had grade 4 glioma. 29 (23.6 %) of tumors were astrocytomas, 24 (19.5 %) were oligoastrocytomas, 15 (12.2 %) were oligodendrogliomas and 55 (44.7 %) were glioblastomas. A seizure was the presenting symptom in 87 (70.7 %) of the patients. The majority, 68 (57.6 %) patients were seizure-free for at least 12 months at some point during follow-up and 47 (39.8 %) patients were seizure-free during the last year of follow-up. Survival for five years from glioma diagnosis (p < 0.001), lower grade of tumor (p < 0.001), IDH mutation (p < 0.001), epilepsy as first symptom (p < 0.001), younger age (p < 0.001) and lack of progression (p = 0.021) correlated with seizure freedom at the end of follow-up. When the results were analyzed separately in survivors and deceased patients, only progression correlated negatively with seizure freedom at the end of follow-up in surviving patients (p = 0.008). In 5-year survivors, longer seizure-free periods were achieved by patients without progression of glioma (p = 0.040) vs patients with progression, or without focal aware (p 0.003) or focal impaired awareness seizures (p = 0.002) vs patients with only focal to bilateral tonic-clonic seizures. In deceased patients, progression (p < 0.001) and lower grade of glioma (p = 0.003) correlated positively and focal aware seizures negatively (p = 0.021) with a longer seizure-free period. In all patients, freedom of seizures at the end of follow-up was less likely for patients who had focal aware (p = 0.015) than for patients without focal aware seizures. CONCLUSION: There are differences in seizure-free times in patients with grade 2–4 glioma and epilepsy. The results suggest that the prognosis of glioma may be the most important factor influencing the prognosis of epilepsy.