Prescription of Memantine During Non-stereotactic, Brain-directed Radiation Among Patients with Brain Metastases: a Population-based Study

Purpose: Whole brain radiation therapy (WBRT) remains an important component of treatment for patients with multiple brain metastases (BrM) but is associated with significant neurotoxicity and memory impairment. Although RTOG 0614 demonstrated that administration of memantine to patients receiving WBRT may reduce radiation-associated cognitive decline, prior literature has suggested that radiation oncologists are hesitant to prescribe memantine. We sought to assess the frequency of memantine prescription in patients managed with non-stereotactic, brain-directed radiation for BrM.

Methods: Patients > 65 years old with newly diagnosed BrM between 2007 and 2016 receiving non-stereotactic, brain-directed radiation (including WBRT) were identified using the SEER-Medicare database. Receipt of memantine with non-stereotactic, brain-directed radiation was defined as any Part D claim for memantine 30 days before or after initiation of non-stereotactic, brain-directed radiation. Clinical and demographic variables among patients who did and did not receive memantine were compared.

Results: Between 2007 and 2016, we identified 6220 patients with BrM receiving non-stereotactic, brain-directed radiation. Only 2.20% of patients (n = 137) received memantine with radiation. Rates were 1.10% versus 5.14% in the period preceding (2007-2013) and following (2014-2016) the publication of RTOG 0614, respectively. Overall utilization of memantine remained low across several clinical, demographic, and prognostic variables.

Conclusion: Despite phase 3 evidence supporting memantine utilization among patients receiving WBRT, our population-based study indicates that rates of memantine prescription are strikingly low, although memantine utilization seems to be increasing since publication of RTOG 0614. Further investigation is needed to identify provider and practice-related barriers preventing incorporation of memantine into management paradigms.