Interaction Between the Contributions of Tumor Location, Tumor Grade, and Patient Age to the Survival Benefit Associated with Gross Total Resection

Background: Gross total resection (GTR) in patients with glioblastoma (GB) and anaplastic astrocytoma (AA) is associated with improved survival. We examined how tumor location, tumor grade, and age affected this benefit. Methods: We selected patients with lobar AA or GB in the Surveillance, Epidemiology, and End Results database from 1999 to 2010. Survival analyses were performed using Kaplan-Meier curves and Cox proportional hazards models. Results: We identified and studied 1429 patients with lobar AA and 12,537 patients with lobar GB in the Surveillance, Epidemiology, and End Results database. In multivariate Cox proportional hazards analysis, GTR of frontal lobe AA was associated with approximately 50% reduction in risk of death compared with subtotal resection (STR) (hazard ratio 0.51; 95% confidence interval, 0.36–0.73; P < 0.001). This hazard ratio corresponds to a median increase in overall survival of >8 years with GTR compared with STR. In nonfrontal AAs, there was no survival difference between GTR and STR (hazard ratio 0.79; 95% confidence interval, 0.58–1.08; P = 0.143). Location-specific survival benefit from GTR in AAs was significant in patients ≤50 years old but was not evident in patients >50 years old. In patients with GB, no location-dependent survival benefit with GTR was observed. Conclusions: Our results demonstrate complex interaction between tumor grade, frontal lobe location, and age in their various contributions to survival benefit gained from GTR. The greatest survival benefit of GTR relative to STR was observed in patients ≤50 years old with frontal AAs.