Stereotactic radiosurgery for distant punctate recurrent IDH-wild type glioblastoma: a single institution experience

Abstract

Abstract Background Glioblastoma (GBM) is a malignant brain tumor that is common and fatal among adults. The standard treatment for GBM involves chemoradiation per Stupp's protocol and additional chemotherapy regimens. However, Stereotactic Radiosurgery (SRS) is frequently used as a single-fraction treatment for punctate recurrent GBM to the contrast-enhancing target on T1 MRI scan without prior assessment of its efficacy. Objective This study aimed to evaluate the safety and efficacy of SRS for patients with distant punctate recurrent IDH-wild type (wt) GBM. Method This retrospective study analyzed the clinical and radiological outcomes of patients with distant punctate recurrent IDH-wt GBM who underwent CyberKnife SRS at the institute between 2013 and 2022. Results A total of five patients (median age of 53 years) with nine lesions were treated with a median margin dose of 20 Gy. The results indicated that SRS, delivered as a single fraction, did not provide good local tumor control. The 3-, 6-, and 12-month local tumor control rates were 77.8%, 66.7%, and 26.7%, respectively. Median progression-free survival (PFS) was 7 months, and median overall survival (OS) was 35 months. Interestingly, the only lesion that did not show radiological progression was not associated with the T2-FLAIR hyperintense area surrounding the original tumor in the MRI. None of the patients presented adverse radiation effects. Conclusion SRS as a treatment for distant punctate recurrent IDH-wt GBM may lead to limited benefit in terms of local tumor control. Expanding the radiosurgical field to consider the T2-FLAIR hyperintense area may be necessary to improve local tumor control and survival outcomes. Further research is needed to improve SRS outcomes by developing new contouring and dosing strategies.