O9.10ANTI-EPILEPTIC TREATMENT IN GLIOMA, A NORWEGIAN POPULATION-BASED STUDY

INTRODUCTION: Symptomatic epilepsy in glioma is traditionally perceived as difficult to treat and refractory to monotherapy. Older AEDs that induce or inhibit CytP450 enzyme systems (enzyme-inducing AED= EIAED) have previously been preferred. There is an increasing focus on the risk of interaction with other drugs with hepatic metabolism. We wanted to study whether newer AEDs with little or no enzyme effect (non-EIAED) are favored in the current treatment of epilepsy in glioma. MATERIALS AND METHODS: We identified all glioma patients with epilepsy in Norway by linking the Cancer Registry of Norway (CRN) and the Norwegian Prescription Database (NorPD). CRN has since 1952 registered information on all neoplasms diagnosed in Norway, and reporting is mandatory by law for clinicians and pathologists. NorPD was founded in 2004 by the Norwegian Institute of Public Health, and includes information on all prescriptions dispensed from all Norwegian pharmacies. We included all patients with glioma grade II-IV who were registered in NorPD. Epilepsy was defined as being registered as taking AEDs under a relevant epileptic diagnostic code. RESULTS: In 2004-2010, CRN registered 2583 patients with glioma grade II-IV, 1477 men and 1106 women. In low grade glioma, 65% had epilepsy and in high grade glioma, 47% had epilepsy. Low grade gliomas with epilepsy were localized in the frontal lobe in 46%. High grade gliomas with epilepsy were localized in the frontal lobe in 28% and the temporal lobe in 27%. In monotherapy or with other AEDs, carbamazepine was used by 34% and valproate by 36% of the 1104 patients with glioma and epilepsy. Patients aged 20-49 years with astrocytoma, and 40-79 years with glioblastoma multiforme (GBM), used non-EIAEDs more frequently than EIAEDs. Levetiracetam was the preferred AED, used by 39% of the 1104 patients. DISCUSSION: The non-EIAED levetiracetam was the most frequently used AED in glioma patients, especially in GBM. GBM patients often have overall survival <1 year and side effects of AEDs are particularly important. Levetiracetam can give cognitive side effects as mood changes or depression, reducing quality of life. Some studies have indicated an anti-tumor effect of valproate and levetiracetam. In this study, we are investigating whether the usage of different AEDs affect overall survival in GBM patients. CONCLUSION: In the Norwegian population 2004-2010, 65% of patients with low grade gliomas and 47% of patients with high grade gliomas had epilepsy. Levetiracetam was the most frequently used AED, especially in GBM. We further investigate the influence of exposure to the separate AEDs on overall survival in the GBM patients, and these results are to be presented.