T57. Prediction of early tumor progression based on pre- and post-operative seizure frequency in low grade gliomas

Abstract

Low-grade gliomas (LGG) are slow-growing tumors characterized by an infiltrative growth pattern and cortical predilection in the central nervous system (CNS). Up to 90% of LGG patients may have seizures as the initial presentation leading to tumor diagnosis, and up to 15% of them develop refractory epilepsy. Predicting which patient will evolve into refractory epilepsy versus have more benign disease course remains a challenge. Moreover, seizure recurrence following surgical resection may predict early tumor recurrence, especially in patients who have achieved long seizure-freedom period. This study analyzed 148 patients meeting inclusion criteria (age > 18 years, LGG diagnosis, at least one seizures event at some point of the disease process). All patients were treated by the Department of Neuro-Oncology and Neurosurgery at University of Texas MD Anderson Cancer Center (MDACC) from Jan/2000 and Dec/2015. Seizure frequency was divided in 4 categories: none, one, few (2–3 seizures) and several (>4 seizures). Perioperative seizures (up to 48 h from surgery) were excluded from this analysis. One hundred sixteen (78.4%) patients had seizures as the initial presentation. On average, the first seizure occurred 4.75 months prior to surgical resection (range 0.1–24.2). Pre-operatively, 54 (36.5%) patients had a single seizure, 23 (15.5%) patients had few seizures and 39 (26.4%) patients had several seizures. After initial event, most patients (74%) were started on antiepileptic drugs (AED). Ninety-two (63%) patients accomplished partial resection, whereas 54 (37%) patients accomplished gross total resection of the tumor. Univariate analysis of seizure frequency between the 6-month pre-op and post-op periods was significant in predicting recurrence-free survival in the following 2 (2-RFS) and 5 (5-RFS) years (p = 0.0379). Patients with no/one seizure pre-op who continued to have no/one seizure in the 6-month post-op period had the highest 2-RFS and 5-RFS (0.984 and 0.667 [CI 95%, 0.889–0.998 and 0.528–0.773], respectively); patients who had no/one seizure pre-op and developed few/several seizures in the 6-month post-op period had the lowest probability of being progression-free in the following 2 and 5 years (0.750 and 0.545 [CI95%, 0.463–0.898 and 0.274–0.753], respectively). Multicovariate cox-regression analysis on RFS based on the seizure frequency change between pre-op and post-op periods revealed that patients with no/one seizure pre-op who had increase in seizure frequency to few/several seizures on the 6-month post-op period had significantly more risk of progression compared to patients who initially had no/one seizure pre-op and continued to have no/one seizure in the 6-month post-op period (HR 2.431 [CI95% 1.318, 4.482], p = 0.0044). Seizure frequency following surgical resection of LGG and the seizure frequency change between the 6-month pre-op and post-op periods predict early tumor recurrence in LGG.