Extending the resection beyond the contrast-enhancement for glioblastoma: feasibility, efficacy, and outcomes

Object: 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) tumour and not the surrounding fluid attenuated inversion recovery (FLAIR) volume. It therefore remains unclear if the resection beyond the CE portion of the tumour if it translates into improved outcomes for patients with GBM. Methods: Adult patients who underwent 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 tumour 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 tumour volumes were 31.9 [13.9-56.1] cm(3) and 78.3 [44.7-115.6] cm(3), respectively. Following surgery, the median [IQR] postoperative CE and FLAIR tumour volumes were 1.9 [0-7.1] cm(3) and 59.7 [29.7-94.2] cm(3), respectively. In multivariate analyses, the postoperative FLAIR volume was not associated with recurrence and/or survival (p > 0.05). However, the postoperative CE tumour 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 tumour as well as those who underwent supratotal resection. Condusions: In this study, the volume of CE tumour remaining after resection is more important than FLAIR volume in regards to recurrence and survival for patients with GBM.