Introduction: Lobar Glioblastoma Multiforme (GBM) are generally more amenable to surgical resection. GBM of the frontal lobe has been reported to have a unique ratio of tumor mutations and prognostic markers when compared to other lobes. GBM which do not arrive de novo but instead progress from a lower grade glioma generally carry a higher incidence of prognostically favorable mutations, frontal lobe positioning and are most often found in patients under 45. There is a paucity of outcomes data analyzing GBM response to treatment by lobe of tumor origin when stratified by age.
Methods: Using the Surveillance, Epidemiology and End Results (SEER) database, we identified 32,004 GBM patients by ICD code during the period of 1990-2014. Survival analyses were performed using log-rank sum evaluations for direct lobe comparison and Wilson-cox regressions for the generation of a multivariate model for all GBM and then per anatomic lobe.
Results: Within the entire GBM cohort, after adjusting for demographics, tumor size, and treatment factors, no significant change in survival was seen in temporal, parietal or occipital lobe when compared to the frontal lobe (all, p>0.05). However, in patients less than 45 years of age, GBM arising from the temporal and parietal lobe was associated with worse survival outcomes after correcting for demographic and size of the tumor (Temporal:HR=1.19, p= 0.01; Parietal: HR = 1.21, p < 0.001; Occipital:HR = 1.20, p= 0.16.) This effect persisted after correcting for radiotherapy and surgical intervention. However, no significance in survival time was seen between lobes in patients who did not receive treatment.
Conclusions: The lobar origin of glioblastoma multiforme was associated with significantly different outcomes. This effect persisted after correcting for demographic and clinical variables. The effect we observed mirrored the incidence of prognostic tumor mutations between lobes, reported elsewhere; however, the origin of this variability remains unclear and is likely multifactorial. This finding warrants further investigation and may help in discovery of variables to guide GBM management.
Patient Care: Identification of prognostic differences in glioblastoma by anatomic location may lead to more specific treatment regimens which will improve patient care and outcome.
Learning Objectives: Anatomic origin of glioblastoma multiforme is associated with different long-term outcomes. Prognostic tumor mutations are associated with this observed anatomic distribution.
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