[Changes in Gamma Knife Radiosurgery(GKRS)in Patients with Metastatic Brain Tumors before and after COVID-19].

The spread of coronavirus disease 2019(COVID-19)is a concern as it may delay the detection of malignant tumors due to delayed medical checkups. We examined changes in the treatment of metastatic brain tumors before and after COVID- 19. A retrospective review of 211 patients with metastatic brain tumors who underwent initial gamma knife radiosurgery between July 2019 and December 2021 was conducted. Data collected include patient age, gender, the Karnofsky performance status(KPS), primary tumor control, number, total volume, and outcome during the COVID-19 emergency declaration period and outside of it. The patient number was 164 outside of the emergency period and 47 during the period. Symptomatic cases(KPS<90)and poor control of the primary site increased during the COVID-19 period. The treatment number and volume of brain metastasis did not change. Metastatic control after 4 months of treatment also showed no difference. The number of symptomatic patients increased during the emergency declaration period, suggesting that COVID- 19 may have reduced the rate of asymptomatic patients being seen. However, these were not enough to affect the prognosis at 4 months. Overall, the COVID-19 pandemic had a small impact on the provision of stereotactic radiotherapy for metastatic brain tumors.