Optimal extent of resection for glioblastoma according to site, extension, and size: a population-based study in the temozolomide era.

The effect of the extent of resection (EOR) on prognosis in glioblastoma may differ depending on various conditions. We evaluated the prognostic impact of the EOR for glioblastoma according to the tumor site, extension, and size. Data from glioblastoma patients who underwent gross total resection (GTR), subtotal resection (STR), or open biopsy between 2005 and 2014 were retrieved from the Surveillance, Epidemiology, and End Results database. Univariate and multivariate analyses for overall survival (OS) were performed. Between 2005-2009 and 2010-2014, the proportion of GTR and STR performed increased from 41.4 to 42.3% and 33.0 to 37.1%, respectively. EOR only affected OS in the 3 years after diagnosis. Median survival in the GTR (n = 4155), STR (n = 3498), and open biopsy (n = 2258) groups was 17, 13, and 13 months, respectively (p < .001). STR showed no significant difference in OS from open biopsy (p = .33). GTR increased OS for midline-crossing tumors. Although STR was more frequently performed than GTR for tumors ≥ 6 cm in size, GTR significantly increased the OS rate relative to STR for tumors 6-8 cm in size (p = .001). For tumors ≥ 8 cm, STR was comparable to GTR (p = .61) and superior to open biopsy (p = .05). GTR needs to be performed more frequently for glioblastoma measuring ≥ 6 cm or that have crossed the midline to increase OS. STR was marginally superior to open biopsy when the tumor was ≥ 8 cm.