SCSS-01. ANTICONVULSANT PROPHYLAXIS IN PATIENTS WITH NEWLY DIAGNOSED BRAIN TUMORS: DOES IT PREVENT FIRST SEIZURES, DOES IT IMPROVE SURVIVAL, AND DO WE BELIEVE THE DATA?
BACKGROUND Despite an American Academy of Neurology Practice Guideline and ASCO/SNO endorsement against the routine use of anticonvulsant prophylaxis in patients with primary and metastatic brain tumors, there remains widespread variation in practice and several unanswered questions. METHODS Exhaustive evidence-based literature searches were conducted, and patient-level data from randomized controlled trials (RCTs) were analyzed to answer three questions: does anticonvulsant prophylaxis reduce the risk of first seizures in patients with primary and metastatic brain tumors; does prophylaxis improve one-year overall survival in patients with primary and metastatic brain tumors; and what effect have practice guidelines had on practice patterns. RESULTS Five RCTs (n=441 patients) addressed anticonvulsant prophylaxis in patients with brain tumors. Overall, anticonvulsant prophylaxis did not reduce the risk of a first seizure in patients with any brain tumor (RR= 0.95 [0.58-1.55], p= 0.85, anticonvulsant prophylaxis vs. placebo), brain metastasis (RR = 0.96 [0.73-1.25], p=0.77, 5 RCTs) or primary brain tumors (RR= 1.03 [0.19-5.72], p=0.97, 4 RCTs). Eleven RCTs of anticonvulsant prophylaxis (n=3767 patients with CNS tumors) provided data for survival analysis and demonstrated a lower RR of death at one year compared to those who did not receive prophylaxis (0.88 [0.81-0.94] p = 0.0006). Physician-reported practice of prescribing anticonvulsant prophylaxis diminished only negligibly after initial guideline publication (54.9% [1 study] vs. 51.6%, [3 studies] p<0.014). CONCLUSION Prophylactic anticonvulsants in patients without a history of seizures does not reduce the risk of first seizures in patients with primary or metastatic brain tumors. Despite this, anticonvulsant prophylaxis provides a small survival benefit at one year, although, this finding may be driven by confounded studies. Rates of anticonvulsant prophylaxis prescription have decreased only minimally and remain very high despite strong evidence against this practice and guideline publication. Evidence-based medicine requires additional mechanisms for encouraging practice change.