Butterfly Glioblastoma - the Impact of Tumor Volumes and Treatment Strategies on Clinical Outcome

Abstract

PurposeButterfly glioblastoma is a rare subgroup of glioblastoma with a bihemispheric tumor crossing the corpus callosum, and is associated with a dismal prognosis. Prognostic factors are previously sparsely described and optimal treatment approaches remain uncertain. We aimed to analyse prognostic factors in butterfly glioblastoma, and to evaluate treatment strategies and outcome in a real-world setting.MethodsWe conducted a retrospective population-based cohort study of patients diagnosed with butterfly glioblastoma in Western Norway between 01/01/2007 and 31/12/2014. Clinical data were extracted from electronic medical records. Molecular and MRI volumetric analyses were retrospectively performed. Survival analyses were performed using Kaplan-Meier method and Cox proportional hazards regression models.ResultsAmong 381 patients diagnosed with glioblastoma, 36 patients (9.4%) met the criteria for butterfly glioblastoma. Median overall survival was 5.9 months (95% CI 2.7-9.2) and three-year survival was 8.3%. Age was strongly associated with poorer outcome, with adjusted hazard ratio (HR) 1.06 (95% CI 1.03-1.10), p<0.001. Best supportive care was associated with poorer survival compared to multimodal treatment (adjusted HR 5.69 (95% CI 1.39-23.38), p=0.02).ConclusionOutcome from butterfly glioblastoma was dismal, with a median overall survival of less than six months. However, long-term survival was comparable to that observed in glioblastoma in general, and multimodal treatment was associated with longer survival. This suggests that patients with butterfly glioblastoma may benefit from a more aggressive treatment approach despite the overall poor prognosis.