Introduction: Butterfly glioblastoma (bGBM) is a rare type of GBM, characterized by bihemispheric involvement and invasion of the corpus callosum. It is thought to have extremely poor outcomes and are generally considered “inoperable”. Recent data supports the beneficial survival impact of extensive resection; however, it is limited to small cases series. The aim of this study was to investigate the shift in survival outcomes in bGBM during a long period, and to look for potential benefits of gross total resection (GTR).
Methods: The data of a total of 521 bGBM patients diagnosed between 1999 and 2021 from the Surveillance, Epidemiology, and End Results (SEER) database were obtained. The cohort was divided into 2 subgroups based on year of diagnosis: pre-temozolomide era (pre-TE; 1999-2006) and temozolomide era (TE; 2007–2021).
Results: As expected, chemotherapy was significantly more common in the TE (51.9% vs. 36%, p=0.007). No other significant differences were found between groups. The TE group was associated with nearly significant improved OS (HR=0.795, 95%CI 0.609-1.036, p=0.067). On multivariate analysis, only radiation therapy was associated with improved survival in the pre-TE group (HR=3.029, p=0.001). However, in the TE group, 4 variables were associated with improved survival: chemotherapy (HR=1.523, p=0.049), radiation therapy (HR=1.676, p=0.006), surgery (HR=1.402, p=0.004) and age (HR=1.031, p< 0.001). For GTR-related analyses, the TE group was further divided into early TE (2007-2016) and late TE (2017-2021). The rate of GTR was significantly higher in the late TE group (19.2% vs. 10.2%, p=0.0013). On multivariate analysis including the 3 therapeutic modalities, GTR was significantly associated with improved OS in the late TE subgroup (HR=1.846, p=0.028).
Conclusion : bGBM cases in the TE are associated with increased rate of chemotherapy use as well as with improved OS. The rate of GTR cases has significantly increased in recent years and is associated with improved OS.
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