Pattern of disease progression following stereotactic radiosurgery in malignant glioma patients

•Majority of malignant glioma patient developed tumor recurrence beyond the SRS field.•1p19 co-deletion is a favorable prognostic factor following SRS.•SRS is one of important element in multidisciplinary treatment for malignant gliomas. The clinical benefit of stereotactic radiosurgery (SRS) in the treatment of malignant glioma remains controversial. We analyzed failure patterns of malignant gliomas following SRS to identify the clinical implications of SRS against these malignancies. We retrospectively reviewed 58 consecutive patients who received SRS with a gamma knife for their malignant glioma from January 2013 to December 2018. A total of 51 patients were available for analysis of failure patterns. Failure patterns were defined by the recurrent tumors’ spatial relation to SRS target as follows: in-field local recurrence, remote recurrence, and leptomeningeal seeding. If patients demonstrated several types of failure patterns simultaneously, we categorized them as a combined failure pattern. In-field local recurrence was found in 47.1% of patients. Other types of failure patterns were as follows: remote recurrence (19.6%), leptomeningeal seeding (13.7%), and combined failure pattern (19.6%). The majority of patients (52.9%) experienced disease progression beyond the radiation field of SRS, which implies limited efficacy of local therapy against these invasive tumors. The prognosis of patients differed according to failure pattern and patients with local recurrence had better survival outcomes compared to other types of disease progression (p-value = 0.0015, log-rank test). This study illustrated that SRS could not improve survival of malignant gliomas significantly even when it had some effect within radiation field. Our findings support utilizing a multidisciplinary treatment strategy to improve the prognosis of malignant gliomas and suggest that SRS is one element of that treatment strategy.