For newly-diagnosed glioblastoma patients, mounting evidence suggests that greater extent of resection (EOR) corresponds to better overall survival.

     For patients with recurrent glioblastoma, however, the value of a second resection at the time of recurrence remains uncertain. Specifically, what proportion of contrast-enhancing recurrent glioblastoma tissue must be removed to improve overall survival and what is the survival benefit beyond this threshold?

     All 170 patients previously underwent resection and adjuvant therapy for a de novo glioblastoma.

     We identified 170 consecutive, recurrent glioblastoma patients treated at the Barrow Neurological Institute from 2001-2011. Clinical and radiographic data were collected retrospectively, including volumetric tumor analysis.

     Median clinical follow-up was 22.6 months and no patient was unaccounted. At the time of recurrence, the median preoperative tumor volume was 26.1 cm3. Following re-resection, median postoperative tumor volume was 3.1 cm3, equating to an 87.4% EOR. The median overall survival was 19.0 months, with a median progression-free survival following re-resection of 5.2 months. Using Cox proportional hazards analysis, age, KPS, and EOR were predictive of survival following repeat resection (p=0.0001). A significant survival advantage was seen with as little as 80% EOR. Recursive partitioning analysis validated these findings and provided additional stratification parameters related to age, extent of resection, and tumor burden.

     This is a retrospective study.

     For recurrent glioblastomas, improvement in overall survival can be attained beyond an 80% extent of resection.

     Interestingly, this lower-limit closely approximates the 78% threshold reported for newly-diagnosed glioblastomas, suggesting that, for a subset of patients, the value of microsurgical resection does not diminish despite biological progression.