Introduction: It is becoming well-established that increasing extent of resection with decreasing residual volume is associated with delayed recurrence and prolonged survival for patients with glioblastoma (GBM). These prior studies are based on evaluating the contrast-enhancing (CE) tumor and not the surrounding fluid attenuated inversion recovery (FLAIR) volume. It therefore remains unclear if resection beyond the CE portion of the tumor translates into improved outcomes for patients with GBM.

Methods: Adult patients who underwent non-biopsy resection of a primary glioblastoma at a tertiary care institution between January 1, 2007 and December 31, 2012 and underwent radiation and temozolomide chemotherapy were retrospectively reviewed. Pre- and postoperative MRI images were measured for CE tumor and FLAIR volumes. Multivariate proportional hazards were used to assess associations with both time to recurrence and death. Values with p<0.05 were considered statistically significant.

Results: 245 patients met the inclusion criteria. The median [IQR] preoperative CE and FLAIR tumor volumes were 31.9 [13.9-56.1] cm3 and 78.3 [44.7-115.6] cm3, respectively. Following surgery, the median [IQR] postoperative CE and FLAIR tumor volumes were 1.9 [0-7.1] cm3 and 59.7 [29.7-94.2] cm3, respectively. In multivariate analyses, the postoperative FLAIR volume was not associated with recurrence and/or survival (p>0.05). However, the postoperative CE tumor volume was significantly associated with both recurrence [HR (95%CI); 1.026 (1.005-1.048), p=0.01] and survival [HR (95%CI); 1.027 (1.007-1.032), p=0.001]. The postoperative FLAIR volume was also not associated with recurrence and/or survival among patients who underwent gross total resection of the CE portion of the tumor as well as those who underwent supratotal resection.

Conclusions: In this study, the volume of CE tumor remaining after resection is more important than FLAIR volume in regards to recurrence and survival for patients with GBM.

Patient Care: This research will guide neurosurgeon decision-making with regards to the extent of resection to optimize patient outcomes.

Learning Objectives: By the conclusion of this session, participants should be able to: 1.) Understand the importance of imaging features for patient outcomes, and 2.) Describe the impact of FLAIR resection on recurrence and survival

References: Chaichana KL, Cabrera-Aldana EE, Jusue-Torres I, Wijesekera O, Olivi A, Rahman M, Quinones-Hinojosa A: When Gross Total Resection of a Glioblastoma Is Possible, How Much Resection Should Be Achieved? World Neurosurg. 2014. Chaichana KL, Jusue-Torres I, Navarro-Ramirez R, Raza SM, Pascual-Gallego M, Ibrahim A, Hernandez-Hermann M, Gomez L, Ye X, Weingart JD, Olivi A, Blakeley J, Gallia GL, Lim M, Brem H, Quinones-Hinojosa A: Establishing percent resection and residual volume thresholds affecting survival and recurrence for patients with newly diagnosed intracranial glioblastoma. Neuro Oncol. 2014;16:113-122. Lacroix M, Abi-Said D, Fourney DR, Gokaslan ZL, Shi W, DeMonte F, Lang FF, McCutcheon IE, Hassenbusch SJ, Holland E, Hess K, Michael C, Miller D, Sawaya R: A multivariate analysis of 416 patients with glioblastoma multiforme: prognosis, extent of resection, and survival. J Neurosurg. 2001;95:190-198. Sanai N, Polley MY, McDermott MW, Parsa AT, Berger MS: An extent of resection threshold for newly diagnosed glioblastomas. J Neurosurg. 2011;115:3-8. Grabowski MM, Recinos PF, Nowacki AS, Schroeder JL, Angelov L, Barnett GH, Vogelbaum MA: Residual tumor volume versus extent of resection: predictors of survival after surgery for glioblastoma. J Neurosurg. 2014;121:1115-1123.