Impact of Immunohistochemical profiling of Glioblastoma multiforme on clinical outcomes: Real-world scenario in resource limited setting.

Objective: Intuition into the molecular pathways of glioblastoma multiforme (GBM) has changed the diagnostic, prognostic, and therapeutic approaches. We investigated the influence of various clinical and molecular prognostic factors on survival outcomes in radically treated GBM patients.

Methods: Medical records of 160 GBM patients treated between January-2012 and December-2018 with surgery followed by post-operative external beam radiotherapy (EBRT) with/without temozolomide (TMZ) were reviewed. Immunohistochemical (IHC) assays were performed for IDH1mutation, ATRX loss, TP53 overexpression and Ki-67% index. Apart from disease and treatment-related factors' influence on clinical outcomes, the impact of IHC markers in prognostication was analyzed using appropriate statistical tests.

Results: The median overall survival (OS) was 14 months. EBRT with concurrent TMZ was given to 60% of patients and 42.5% completed the standard Stupp-protocol. Significant improvements in OS was observed in patients aged ≤ 50years (2-year OS: 22.1% vs. 12.5%, p = 0.001), those who underwent gross total resection (2-year OS: 21.8% vs. 12.8%, p = 0.002), received concurrent TMZ (21.9% vs. 12.5%, p = 0.005), completed the entire Stupp-protocol (2-year OS: 23.4% vs. 6.5%, p = 0.000), and with Ki-67 index <20% (2-year OS: 23.3% vs. 11.6%, p = 0.015). On multivariate analysis, IDH1 mutation, ATRX loss, TP53 expression, and Ki-67 ≤ 20% were significant prognosticators of outcomes.

Conclusion: GBM patients treated with concurrent chemoradiation and those who completed the full Stupp-protocol experienced better survival outcomes. Molecular biology significantly impacts clinical outcomes and plays a key deterministic role in newer management strategies.