FUNCTIONALLY GUIDED SUPRAMAXIMAL RESECTION OF IDH-WILDTYPE GLIOBLASTOMAS AND THE EFFECT ON PROGRESSION FREE SURVIVAL

Abstract

INTRODUCTION: Gross total resection (GTR), defined as complete resection of enhancing tumour on post‐operative MRI, increases progression free survival (PFS) in patients with glioblastoma. We have extended the concept of functionally guided supramaximal resection (SMR) where the aim of surgery is to resect up to 2 cm beyond the enhancing tumour in all directions, limited only by functional boundaries. Boundaries are identified by pre‐operative diffusion tensor imaging (DTI) scans, to estimate white matter fibre tract location, and awake craniotomy with cortical and subcortical stimulation. METHODS: Prospective non‐randomised functionally guided surgical resection was undertaken in all IDH‐wildtype glioblastomas undergoing primary surgical resection by the senior author between 2012‐2017. Based on post‐operative MRI scans, data on extent of tumour resection were analysed calculating tumour, brain and post resection volumes. Patients were then categorised into three different extent of resection groups: subtotal resection (STR), GTR, and SMR. All patients underwent post‐operative radiotherapy and chemotherapy as per the Stupp protocol and were followed up with 3‐monthly MRI scans. RESULTS: 69 cases of IDH‐wildtype glioblastoma underwent resection within the timeframe. Survival data are currently available for 45 cases. The outcome measure is PFS, where progression is defined as recurrence of tumour. For actual treatment received, median PFS was 43.9 months (95% CI, 22.8‐ 89.8 months) in the SMR group, 29.3 months (95% CI, 7.4‐72.3 months) in GTR group and 13.3 months (95% CI, 10.3‐27.6 months) in the STR group. The Kaplan‐Meier survival curves of the three groups are clearly separated with no crossing. The logrank test indicates there is a significant difference (P value = 0.0003) between the survival curves of the three groups. There was no difference in the incidence of post‐operative neurological deficit between the three groups. CONCLUSION: Supramaximal resection provides a significant increase in PFS compared to the current accepted standard of GTR.