Germanwala, Anand V.

Abstract Recurrence pattern in high grade glioma is classified as local and distant recurrence based on distance from original resection cavity and radiation field. We report the first series of three cases of O6-methylguanine-DNA methyltransferase (MGMT) promoter methylated high grade glioma with distant recurrence without local recurrence throughout the disease course. Patient 1: 65 year-old female with WHO grade 4 glioblastoma, isocitrate dehydrogenase enzyme (IDH) wild type (WT), MGMT methylated. She underwent gross total resection followed by Stupp protocol. Postoperative ischemic volume was < 1 ml. Distant recurrence occurred 4 months after completion of Stupp protocol. Patient 2: 55 year-old male with WHO grade 4 glioblastoma, IDH wild type, MGMT methylated. He underwent gross total resection followed by Stupp protocol. Postoperative ischemic volume was 18 ml. Distant recurrence occurred 5 months after completion of Stupp protocol. Patient 3: 31 year-old male with WHO grade 4 astrocytoma, IDH mutant, MGMT promoter methylated. He underwent gross total resection followed by Stupp protocol. Postoperative ischemic volume was 2 ml. Distant recurrence occurred 10 months after completion of Stupp protocol. Distant recurrence is more common in MGMT promoter methylated tumors. All 3 patients in our case series had poor outcomes after distant recurrence without local recurrence at the original tumor site. This observation indicates good local control in MGMT promoter methylated high grade glioma with current standard treatment. For one patient, next generation sequencing (NGS) was available for both original and recurrent tumor and did not reveal any major differences in the genetics of original tumor and distant recurrent tumor other than temozolomide induced high tumor mutational burden in the distant recurrent tumor. Understanding risk factors for distant recurrence in MGMT promoter methylated high grade gliomas and investigating correlations between recurrences will help plan therapeutic strategies to prevent distant recurrence and improve outcomes.

Abstract BACKGROUND Glioblastoma diagnostic criteria have been redefined with the 5th edition of WHO classification of tumors of the central nervous system. Glioblastomas are defined as IDH wildtype diffuse astrocytic glioma tumors with one of the following features: microvascular proliferation, or necrosis, or TERT promoter mutation, or EGFR gene amplification, or +7/-10 chromosome copy number changes. The aim of this study is to establish the impact of extent of resection in overall survival (OS) and progression free survival (PFS) in glioblastoma, IDH-wildtype (WT), WHO grade 4 (WHO 2021). METHODS Systematic literature search was performed using the following databases: PubMed, Web of Science, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews and ClinicalTrials.gov to identify studies comparing OS and PFS after gross total resection (GTR) vs subtotal resection (STR) or biopsy for glioblastoma IDH-WT. Prognostic hazard ratios (HR) for OS and PFS were analyzed using a random-effects model. RESULTS We identified 1439 publications. Nine studies met inclusion/exclusion criteria. 788 patients underwent GTR out of 1818. The meta-analysis showed a significant increase in OS and PFS duration when undergoing GTR for glioblastoma IDH-WT with a median OS of 20 months 95% CI (17-25) compared to 12 months 95% CI (9-15) for STR or biopsy and a median PFS of 11 months 95% CI (9-12) for GTR compared to 7 months 95% CI (5-7) for STR or biopsy respectively. GTR showed a 49% significant reduction of mortality risk HR=0.51 95%CI (0.42-0.59) and a 44% significant reduction of progression risk HR=0.56 95%CI (0.41-0.71) compared to STR or biopsy. CONCLUSIONS This systematic review indicates that GTR may be associated with improved OS and PFS compared to STR or biopsy for Glioblastoma, IDH-WT, WHO grade 4 (WHO 2021). However, this is limited by variable study design and significant clinical and methodological heterogeneity among studies.