Evolving landscape of glioblastoma research

BACKGROUND: Glioblastoma is the most aggressive type of brain tumor. Here, we examine the evolution of glioblastoma treatment and survival across different study types over nearly a century. Furthermore, we map the landscape of glioblastoma research to track the potential influence of publication bias on perceived progress and assess sex disparities in authorship across time, study type and geographic region. METHODS: We analyzed a comprehensive dataset of glioblastoma research published from 1947-2022. A manual review of 19,668 articles yielded 2232 articles passing the inclusion criteria. RESULTS: Overall, we observed an increased median overall survival (OS, slope = 0.16 months per year, Pearson's r = 0.23, p = 1.65e-44) for all study types. Nevertheless, reported survival outcomes varied by treatment modality. Only tumor treating fields (fitted median OS from 14.5 to 21.4 months, slope = 0.53 months per year) showed a stronger increase in positive outcomes than radiotherapy with concomitant and adjuvant temozolomide (fitted median overall survival from 12.0 to 20.0 months, slope = 0.31 months per year). Despite making up only 5.6% of all studies, randomized controlled trials had the highest cumulative impact factor and citation count and US-based researchers dominated across all study types (33.9%). Women continued to be underrepresented, particularly as last authors (25.2% female first, 18.5% female last). CONCLUSION: The 75 years of reported survival of patients with glioblastoma document a slow increase in overall survival. While research by women as first authors shows an upward trend, gender inequality persists, particularly in the last authorship.