IDH1 and glioblastoma: Of interest in this context, and corroborating earlier studies in GBM IDH-wt with data on MGMT methylation status, is the fact that the prognostic benefit of the incomplete resection was not different from biopsy (36, 37).The role of the extent of surgery and its effect on survival are controversial, with those proposing precise thresholds for the extent of resection to achieve a significant effect on survival, while others suggest a continuous relationship between the extent of surgery and survival (38).